Android Getting Started Example Complete Code

Mobile 2023-09-06 04:23:16 views: null



A Simple Getting Started Demo for Hello World



①MainActivity code is as follows:


package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

/**
 *      步骤
 *          MainActivitt.java    代码中设置显示的内容视图        setContentView(R.layout.activity_main);
 *          activity_main.xml    中申明内容 tools:context=".MainActivity">
 *          AndroidManifest.xml  中文件注册申明名字  android:name=".MainActivity">
 *
 *      2021-5-7 13:55:15
 *
 */

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}


②The activity_main.xml code is as follows:


<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:textColor="#FF0000"
        android:textSize="30sp"
        android:background="#00ff00"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:shadowColor="#F9F900"
        android:shadowDx="10.0"
        android:shadowDy="10.0"
        android:shadowRadius="3.0"
        android:text="带阴影的 Hello World！"
        android:textColor="#9C27B0"
        android:textSize="30sp"
        tools:ignore="MissingConstraints"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>


③AndroidManifest.xml code is as follows:


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.MyApplication" >
        <activity android:name=".MainActivity">
            <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>


The display page effect is as follows:
Guyu





Example Demo01: Click the control switch to display the prompt



①The code of src/main/java/ MainActivity01.java is as follows:


package com.example.myapplication;

import android.os.Bundle;
import android.widget.CompoundButton;
import android.widget.Switch;
import android.widget.Toast;
import android.widget.ToggleButton;

import androidx.appcompat.app.AppCompatActivity;

/**
 *      步骤:
 *          MainActivity01       代码中设置显示的布局内容视图        setContentView(R.layout.activity_main01);
 *          activity_main01.xml  中申明内容 tools:context=".MainActivity01">
 *          AndroidManifest.xml  中申明名字 android:name=".MainActivity01">
 *
 *
 */

public class MainActivity01 extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener{

    private ToggleButton tbtn_open;
    private Switch swh_status;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main01);

        tbtn_open = (ToggleButton) findViewById(R.id.tbtn_open);
        swh_status = (Switch) findViewById(R.id.swh_status);
        tbtn_open.setOnCheckedChangeListener(this);
        swh_status.setOnCheckedChangeListener(this);
    }

    设置监听事件   toggleButton 是通过 checked 属性来控制开关
    @Override
    public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
        switch (compoundButton.getId()){
            case R.id.tbtn_open:
                if(compoundButton.isChecked()) Toast.makeText(this,"打开声音",Toast.LENGTH_SHORT).show();
                else Toast.makeText(this,"关闭声音",Toast.LENGTH_SHORT).show();

                break;
            case R.id.swh_status:
                if(compoundButton.isChecked()) Toast.makeText(this,"开关:ON",Toast.LENGTH_SHORT).show();
                else Toast.makeText(this,"开关:OFF",Toast.LENGTH_SHORT).show();
                break;
        }
    }
}


②The code of src /main/res/layout/ activity_main01.xml is as follows:


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity01">


    <!--开关-->
    <ToggleButton
        android:id="@+id/tbtn_open"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"
        android:layout_gravity="center"
        android:textOff="关闭声音"
        android:textOn="打开声音" />

    <Switch
        android:id="@+id/swh_status"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        />
</LinearLayout>


③The code of src/main/AndroidManifest.xml is as follows:


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.MyApplication" >
        <activity
            android:name=".MainActivity01">

<!--   修改类名   android:name=".MainActivity02">-->
            
            <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
    
                </intent-filter>
        </activity>
    </application>
</manifest>


④ After the usb data cable is connected to the device, run it to demonstrate in the device. Click to display the following content:



Guyu





Example Demo02: Click the button to display the prompt



①MainActivity02 code is as follows:


package com.example.myapplication;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

/**
 *     点击按钮示例 步骤  参考示例： https://blog.csdn.net/a772304419/article/details/114752848
 *
 *           1、首先在layout布局创建 activity_text_view.xml 为应用添加一个id为hellotextView的textview和一个id为hellobutton的button，
 *           2、代码和控件用到的字符串定义在 values 下的 string.xml 中声明显示文字信息
 *           3、主程序中 MainActivity02 定义 button 点击后改变 textview 显示的文本，并且弹出 Toast 提示信息
 *           4、AndroidManifest.xml 中申明主程序的类名
 *
 */
public class MainActivity02 extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_text_view);

        //得到按钮实例
        Button hellobtn = (Button)findViewById(R.id.hellobutton);
        //设置监听按钮点击事件
        hellobtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //得到textview实例
                TextView hellotv = (TextView)findViewById(R.id.hellotextView);
                //弹出Toast提示按钮被点击了
                Toast.makeText(MainActivity02.this,"Clicked!你点击了该按钮!!!",Toast.LENGTH_SHORT).show();
                //读取strings.xml定义的interact_message信息并写到textview上
                hellotv.setText(R.string.interact_message);
            }
        });
    }
}


②The code of src/main/res/values/strings.xml is as follows:


<resources>
    <string name="app_name">My Application</string>
    <string name="button_send">说点什么吧！</string>
    <string name="default_message">点击下面的按钮！</string>
    <string name="interact_message">你点击了该按钮！</string>
</resources>

③The activity_text_view.xml code is as follows:


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <TextView
        android:id="@+id/hellotextView"
        android:layout_width="fill_parent"
        android:layout_height="380dp"
        android:gravity="center"
        android:text="@string/default_message"
        android:textColor="#FF9800" />


    <Button
        android:id="@+id/hellobutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="@string/button_send"
        android:textColor="#FF0000" />

</LinearLayout>


④The AndroidManifest.xml code is as follows:


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.MyApplication" >
        <activity
            android:name=".MainActivity02">

<!--   修改类名   android:name=".MainActivity02">-->

            <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />

                </intent-filter>
        </activity>
    </application>
</manifest>


Guyu





Example Demo03: RelativeLayout (relative layout) button remote control



The code of src/main/res/layout/day5241.xml is as follows:


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/day524"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<!--        设置一个UI控件：文本框视图，定义标题上边距水平居中和文本字体大小加粗颜色-->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:layout_marginTop="20dp"
        android:background="#00FFFF"
        android:text="相对布局的实例"
        android:textSize="35dp"
        android:textStyle="bold"
        android:textColor="#000000" />

<!--    定位五个按钮，把按钮3排版好位于父类容器的中部为参考按钮-->
    <Button
        android:id="@+id/button_3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textColor="#FF0000"
        android:text="中间-3" />

<!--    方法一：相对于控件布局，设置按钮1在按钮3的上边且在该控件的左边-->
    <Button
        android:id="@+id/button_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@id/button_3"
        android:layout_toLeftOf="@id/button_3"
        android:text="左上-1" />

<!--    方法二：相对于父布局，设置按钮1对齐在整个布局上边且在该整个布局的左边-->
<!--    <Button-->
<!--        android:id="@+id/button_1"-->
<!--        android:layout_width="wrap_content"-->
<!--        android:layout_height="wrap_content"-->
<!--        android:layout_alignParentTop="true"-->
<!--        android:layout_alignParentLeft="true"-->
<!--        android:text="左上-1" />-->


    <Button
        android:id="@+id/button_2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@id/button_3"
        android:layout_toRightOf="@id/button_3"
        android:text="右上-2" />

    <Button
        android:id="@+id/button_4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/button_3"
        android:layout_toLeftOf="@id/button_3"
        android:text="左下-4" />

    <Button
        android:id="@+id/button_5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/button_3"
        android:layout_toRightOf="@id/button_3"
        android:text="右下-5" />
</RelativeLayout>


The page effect is as follows:

Guyu





Example Demo04: TableLayout (table layout) button stretch



The code of src/main/res/layout/day5242.xml is as follows:


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <!-- 定义一个单独按钮和一个表格布局内三按钮，指定第2列允许收缩，第3列允许拉伸  注都是从0开始！-->
    <TableLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:shrinkColumns="1"
        android:stretchColumns="2">

        <!--单独的按钮 放在TableLayout里面占据一行-->
        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button" />

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="1按钮" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="2被指定收缩" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="3被指定拉伸" />
        </TableRow>

    </TableLayout>

    <!--
     定义1个表格布局，指定第2列隐藏，collapseColumns为隐藏列从0开始，
     如下定义collapseColumns="1" 表示为三个按钮隐藏第二个-->

    <TableLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:collapseColumns="1">

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="1后一个被隐藏" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="2被指定隐藏按钮" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="3前一个被隐藏" />
        </TableRow>

    </TableLayout>

    <!--定义第2个表格布局，指定第2列和第3列可以被拉伸-->
    <TableLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:stretchColumns="1,2">

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="1按钮" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="2拉伸" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="3拉伸" />
        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="1按钮" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="2拉伸" />
        </TableRow>
    </TableLayout>
</LinearLayout>


The page effect is as follows:

Guyu





Example Demo05: GridLayout (grid layout) button counter



The code of src/main/res/layout/day525.xml is as follows:


<?xml version="1.0" encoding="utf-8"?>
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:columnCount="4"
    android:rowCount="6">

    <!--  GridLayout 网格布局  设置多个按钮组件显示网格布局
            columnCount="4"：网格布局设置 4 列
            rowCount="6"：网格布局设置 6 行
            android:layout_columnSpan="4"：表示当前子控件占 4 列。
            android:layout_marginLeft="5dp"：设置控件内容距离左侧的距离
            android:layout_gravity="fill"：设置内容对齐方式为填充
     -->

    <TextView
        android:layout_columnSpan="4"
        android:layout_gravity="fill"
        android:layout_marginLeft="5dp"
        android:layout_marginRight="5dp"
        android:layout_marginTop="5dp"
        android:background="#FFCCCC"
        android:text="0"
        android:textSize="50sp" />

    <Button
        android:layout_columnSpan="2"
        android:layout_gravity="fill"
        android:text="回退" />

    <Button
        android:layout_columnSpan="2"
        android:layout_gravity="fill"
        android:text="清空" />

    <Button
        android:layout_gravity="fill"
        android:text="+" />

    <Button
        android:layout_gravity="fill"
        android:text="1" />

    <Button
        android:layout_gravity="fill"
        android:text="2" />

    <Button
        android:layout_gravity="fill"
        android:text="3" />

    <Button
        android:layout_gravity="fill"
        android:text="-" />

    <Button
        android:layout_gravity="fill"
        android:text="4" />

    <Button
        android:layout_gravity="fill"
        android:text="5" />

    <Button
        android:layout_gravity="fill"
        android:text="6" />

    <Button
        android:layout_gravity="fill"
        android:text="*" />

    <Button
        android:layout_gravity="fill"
        android:text="7" />

    <Button
        android:layout_gravity="fill"
        android:text="8" />

    <Button
        android:layout_gravity="fill"
        android:text="9" />

    <Button
        android:layout_gravity="fill"
        android:text="/" />

    <Button
        android:layout_width="wrap_content"
        android:layout_gravity="fill"
        android:text="." />

    <Button
        android:layout_gravity="fill"
        android:text="0" />

    <Button
        android:layout_gravity="fill"
        android:text="=" />

</GridLayout>


The page effect is as follows:

Guyu





Example Demo06: ConstraintLayout (constraint layout) click the button to switch pictures



①MainActivity0706 code is as follows:


package com.example.myapplication

import android.os.Bundle
import android.widget.Button
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity


/**
 *     点击按钮切换显示图片 示例：
 *
 *           1、首先在layout布局创建 day706_01.xml 为应用添加一个ImageView和一个button，
 *           2、将显示的 ImageView 图片定义在 res/drawable 中修改图片文件名信息，如:image_1.jpg...
 *           3、在主程序中 MainActivity0706 定义 一组图片的数组,并且一个按钮 点击切换查看数组图片
 *           4、清单文件 AndroidManifest.xml 中申明主程序的类名
 *
 */

class MainActivity0706 : AppCompatActivity() {

    var iv: ImageView? = null
    var btn: Button? = null

    //声明图片资源数组
    val imgs:Array<Int> = arrayOf(
            R.drawable.a1,
            R.drawable.a2,
            R.drawable.a3,
            R.drawable.a4,
            R.drawable.a5,
            R.drawable.a6,
            R.drawable.a7,
            R.drawable.a8,
            R.drawable.a9,
            R.drawable.a10,
            R.drawable.a11,
            R.drawable.a12,
            R.drawable.a13,
            R.drawable.image_1,
            R.drawable.image_2
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.day706_01)

        var index:Int = 0
        //找到控件
        iv = findViewById(R.id.iv)
        btn = findViewById(R.id.btn)
        //设置图片点击监听器
        btn?.setOnClickListener {
            iv?.setImageResource(imgs[index++%imgs.size])
        }
    }
}


②The picture of src/main/res/drawable is as follows:

Guyu

...The picture size format is generally 640×1136, as shown below, refer to picture a6.jpg

insert image description here

③day706_01.xml code is as follows:


<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/iv"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintHeight_percent="0.99"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="切换图片"
        android:textColor="#00FF00"
        app:layout_constraintBottom_toBottomOf="@+id/iv"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>


④The AndroidManifest.xml code is as follows:


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.MyApplication" >
        <activity
            android:name=".MainActivity0706">

<!--   修改类名   android:name=".MainActivity02">-->

            <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />

                </intent-filter>
        </activity>
    </application>
</manifest>


Click the switch picture button page renderings are as follows:

Guyu

Through this example, you will think of how to make it automatically switch pictures. The following example uses the RxJava timed task to set a group of pictures to automatically switch picture effect code examples in 2 seconds.




Example Demo07: ConstraintLayout (constraint layout) automatic switching of picture timing





①MainActivity0706 code is as follows:


package com.example.myapplication

import android.annotation.SuppressLint
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import com.example.myapplication.databinding.ActivityMainBinding
import io.reactivex.Observable
import io.reactivex.ObservableTransformer
import io.reactivex.android.schedulers.AndroidSchedulers
import io.reactivex.schedulers.Schedulers
import java.util.concurrent.TimeUnit


/**
 *     
 *     点击按钮切换显示图片 示例：
 *
 *           1、首先在 layout 布局创建 activity_main.xml 为应用添加一个 ImageView 和一个 button，
 *           2、将显示的 ImageView 图片定义在 res/drawable 中修改图片文件名信息，如:image_1.jpg...
 *           3、在主程序中 MainActivity 定义 一组图片的数组,并且一个按钮 点击切换查看数组图片
 *           4、清单文件 AndroidManifest.xml 中申明主程序的类名为 .MainActivity
 *
 *      注：
 *           在 Activity 或 Dialog 中，加载界面后，通过 findViewById 方法，来给声明的控件赋值；
 *           1、在没有加载之前，获取的控件为 null
 *           2、控件多了， findViewById 特麻烦
 *      解决方法：
 *          1、使用  'kotlin-android-extensions' 插件
 *              在 Build.gradle 中，添加插件；在代码中，直接使用控件的 id 来作为控件本身，此方法已被弃用；
 *          2、ViewBinging 的使用
 *              1-1、在 Build.gradle 中，添加字段 buildFeatures 为 true
 *               在代码中①声明一个 binding   var binding: ActivityMainBinding? = null
 *                      ②初始化 binding     binding = ActivityMainBinding.inflate(layoutInflater)
 *                      ③设置布局          setContentView(binding!!.root)
 *
 *              1-2、在代码中通过 binding 来引用控件
 *                  binding?.tvMsg?.text = "测试文本"
 *
 *          3、使用 RxJava 引包      implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
 *              方法二：采用 RXJava 定时任务比 for 循环遍历更简单
 */

class MainActivity0706 : AppCompatActivity() {

    //声明binding
    var binding: ActivityMainBinding?= null

//    var iv: ImageView? = null
//    var btn: Button? = null


    @SuppressLint("CheckResult")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        //初始化binding
        binding = ActivityMainBinding.inflate(layoutInflater)
        //设置布局界面
        setContentView(binding?.root)

//        setContentView(R.layout.activity_main)

        //声明图片资源数组
        val imgs:Array<Int> = arrayOf(
                R.drawable.a1,
                R.drawable.a2,
                R.drawable.a3,
                R.drawable.a4,
                R.drawable.a5,
                R.drawable.a6,
                R.drawable.a7,
                R.drawable.a8,
                R.drawable.a9,
                R.drawable.a10,
                R.drawable.a11,
                R.drawable.a12,
                R.drawable.a13,
                R.drawable.image_1,
                R.drawable.image_2
        )

        //记录当前图片数组的索引
        var index:Int = 0


        //找到控件
//        iv = findViewById(R.id.iv)
//        btn = findViewById(R.id.btn)

        //设置图片点击监听器
//        btn?.setOnClickListener {
//            iv?.setImageResource(imgs[index++%imgs.size])
//        }

        //设置控件及控件的事件
        binding?.btn?.setOnClickListener {
            //设置图片；每次点击时将 index向有移一位，
            binding?.iv?.setImageResource(imgs[++index % imgs.size])
        }

        //方法一：for 循环 遍历
//        for(i in 0 until 2000){
//            //每隔2秒，切张图片
//          binding?.iv?.setImageResource(imgs[++index % imgs.size])
//            val observable = Observable.timer(2000L*i, TimeUnit.MILLISECONDS)
//               .compose(ObservableTransformer<Any, Any> { upstream -> //线程调度
//                   upstream.subscribeOn(Schedulers.io())//在子线程中发生
//                       .observeOn(AndroidSchedulers.mainThread()) //在主线程中处理
//
//               })
//                .subscribe {
//                    //处理结果
//                    binding?.iv?.setImageResource(imgs[++index % imgs.size])
//                }
//        }

        //方法二：采用RXJava 定时任务
        Observable.interval(2000,TimeUnit.MILLISECONDS)
                .compose(ObservableTransformer<Any,Any>{upstream ->
                    upstream.subscribeOn(Schedulers.io())
                            .observeOn(AndroidSchedulers.mainThread())
                })
                .subscribe {
                    binding?.iv?.setImageResource(imgs[++index % imgs.size])
                }
    }
}


②app/build.gradle configuration code is as follows:


plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
	
	//
    buildFeatures {
        viewBinding = true
    }
}

dependencies {

    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'com.google.android.material:material:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
    implementation "androidx.core:core-ktx:+"
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"

    //导入RXJava包
    implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
}
repositories {
    mavenCentral()
}


In Build.gradle:
add plugin

apply plugin: ‘com.android.application’
apply plugin: ‘kotlin-android’
apply plugin: ‘kotlin-android-extensions’

Add bound view

buildFeatures {
viewBinding = true
}

Import the RxJava package

implementation ‘io.reactivex.rxjava2:rxandroid:2.1.1’



After synchronization, the running page effect will automatically switch pictures in 2s




Example Demo08: LinearLayout (linear layout) slot machine definition picture rotation random selection of a picture





①MainActivity0722 code is as follows:


package com.example.myapplication

import android.annotation.SuppressLint
import android.os.Bundle
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity
import com.example.myapplication.databinding.Day719Binding
import io.reactivex.Observable
import io.reactivex.ObservableTransformer
import io.reactivex.Scheduler
import io.reactivex.android.schedulers.AndroidSchedulers
import io.reactivex.disposables.Disposable
import io.reactivex.schedulers.Schedulers
import java.util.concurrent.TimeUnit

/**
 *     2021-7-22 11:39:43
 *          老虎机实例：
 *              定义八张图片旋转随机停止落选某张图片
 *
 */

class MainActivity0722 : AppCompatActivity() {

    //Day722Binding 命名为布局名组合+绑定； 声明的是布局文件不为空
    var binding : Day0722Binding? = null

    //声明图片控件数组
    val imgs: ArrayList<ImageView?> = ArrayList()

    //
    var observable : Disposable? = null

    //onCreate方法用来初始化Activity实例对象
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        //layoutInflater 布局增压泵；对于一个没有被载入或者想要动态载入的界面,
        // 都需要使用inflate来载入.之后需定义声明布局文件不为空
        binding = Day722Binding.inflate(layoutInflater)

        //加载布局文件方法
//        setContentView(R.layout.main);
        setContentView(binding?.root)

        //设置图片控件大小  之后需定义声明图片控件数组
        imgs.add(binding?.iv1)
        imgs.add(binding?.iv2)
        imgs.add(binding?.iv3)
        imgs.add(binding?.iv4)
        imgs.add(binding?.iv5)
        imgs.add(binding?.iv6)
        imgs.add(binding?.iv7)
        imgs.add(binding?.iv8)

        //计算屏宽，得到iv宽高
        val ivSize = resources.displayMetrics.widthPixels / 3

        //遍历控件设置大小
        for (item in imgs) {
            //先拿回原本的布局属性
            var  params = item?.layoutParams
            //再修改其长宽高  布局属性 3×3  ,之后需定义计算屏宽，得到iv 宽高
            params?.width = ivSize
            params?.height = ivSize
            //最后修改后的属性设置回去
            item?.layoutParams = params

        }
        //ivCenter 设置图片中间设置大小
        var params = binding?.ivCenter?.layoutParams
        //设置中间的宽高
        params?.width = ivSize
        params?.height = ivSize
        //重设回来
        binding?.ivCenter?.layoutParams = params

        //点击按钮触发事件，为 Button 注册监听器
        binding?.btnStart?.setOnClickListener {
            //先生成一个随机停止的落选数
            val runNumber = (Math.random()*100).toInt()

            //启动定时器，设置每隔一秒自动切换一张图片
//            var index = 1L
            var index = 1

            //利用RxJava 之后需先定义 observable
           /* observable = Observable.interval(index*100, TimeUnit.MILLISECONDS)
                    .compose(ObservableTransformer<Any,Any> {  upstream ->
                        upstream.subscribeOn(Schedulers.io())
                                .observeOn(AndroidSchedulers.mainThread())
                    })
                    .subscribe {
                        //控制 src 属性, 之后需先定义设置图片的显示位置设置
                        setImgSrc((index ++ %imgs.size).toInt())
                        observable?.dispose()
                    } */
            setDelayDisplay(index*10,index,runNumber)
        }
    }


    //延迟显示指定的位置，delay:延迟时间；Index:在哪个控件上显示
    @SuppressLint("CheckResult")
    fun setDelayDisplay(delay: Int, index: Int, stopIndex: Int) {
        Observable.timer(delay.toLong(), TimeUnit.MILLISECONDS)
                .compose(ObservableTransformer<Any,Any> {
                    upstream ->
                        upstream.subscribeOn(Schedulers.io())
                                .observeOn(AndroidSchedulers.mainThread())
                })
                .subscribe {
                    setImgSrc((index%imgs.size).toInt())
                    //再次延迟操作
                     if (index < stopIndex) {
                         val nextIndex = index+1
                         setDelayDisplay(nextIndex*10,nextIndex,stopIndex)
                     }
               }
    }

    //设置图片的src 且只显示一张，其它都不显示
     fun setImgSrc(index : Int) {
        //计算图片总个数
         val totalCount = imgs.size

        //遍历循环
         for (i in 0 until totalCount) {
             //
             if (index == i) {
                 imgs[i]?.setImageResource(R.drawable.img_selected)
             } else {
                 imgs[i]?.setImageResource(0)
             }
         }
    }
}


②The picture of src/main/res/drawable is as follows:

Guyu
...The picture size format is generally 147×148, as shown below, refer to picture b1.jpg

Guyu

③day722_01.xml code is as follows:


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity0722 ">

    <!-- 图片 -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_weight="1">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <ImageView
                android:id="@+id/iv1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b1"
                android:padding="10dp"
                android:src="@drawable/img_selected"/>

            <ImageView
                android:id="@+id/iv2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b2"
                android:padding="10dp" />

            <ImageView
                android:id="@+id/iv3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b3"
                android:padding="10dp" />

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <ImageView
                android:id="@+id/iv8"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b1"
                android:padding="10dp" />

            <ImageView
                android:id="@+id/ivCenter"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b1"
                android:padding="10dp"
                android:visibility="invisible"/>

            <ImageView
                android:id="@+id/iv4"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b2"
                android:padding="10dp" />

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <ImageView
                android:id="@+id/iv7"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b3"
                android:padding="10dp" />

            <ImageView
                android:id="@+id/iv6"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b2"
                android:padding="10dp" />

            <ImageView
                android:id="@+id/iv5"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/b1"
                android:padding="10dp" />

        </LinearLayout>

    </LinearLayout>

    <Button
        android:id="@+id/btnStart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开始" />

</LinearLayout>


④The code of src/main/res/drawable/img_selected.xml is as follows:

From fast to slow, the transparent effect of the rotation shows the mark box


<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <stroke
        android:width="15dp"
        android:color="#8FFF" />
</shape>


⑤ The app/build.gradle configuration code is as follows:


plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    buildFeatures {
        viewBinding = true
    }
}

dependencies {

    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'com.google.android.material:material:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
    implementation "androidx.core:core-ktx:+"
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"

    //导入RXJava包
    implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
}
repositories {
    mavenCentral()
}


Click the start button and the page will randomly stop to a certain picture according to the rotation from fast to slow. The effect is as follows:

Guyu




  • RxJava [findViewById] link:

    Link: https://pan.baidu.com/s/1ASWWozcc6DDIFKLYzaVRMQ
    Extraction code: 49ew




















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