android：对话框AlertDialog

安卓对话框是的实现需要用到 AlertDialog.Builder 实例对象

之后我们就用这个对象的以下方法

下面列举几个常用的方法

setTitle():设置 标题  
setview():设置 自定义页面（下面会细讲自定义页面）
setPositiveButton():一般用于确定功能
setNegativeButton()：一般用于取消功能
setOnShowListener():对话框出现
setOnCancelListener()：对话框消失

show():用于展示对话框 注意：如果没有这句话你的对话框不会显示

一般我们在自定义页面的时候不会都写在一个页面中，造成代码杂糅

往往都需要新建一个页面，在此是不需要新建新的Activity，只需要一个Layout布局页面

这里简单写一个

代码如下：

<?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"
    android:orientation="vertical">

    <EditText
        android:id="@+id/ed_ip"
        android:layout_width="269dp"
        android:layout_height="83dp"
        android:layout_marginTop="28dp"
        android:layout_marginEnd="68dp"
        android:ems="10"
        android:gravity="center"
        android:hint="请输入IP，例如192.168.1.1"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/ed_port"
        android:layout_width="261dp"
        android:layout_height="86dp"
        android:layout_marginTop="120dp"
        android:layout_marginEnd="72dp"
        android:ems="10"
        android:gravity="center"
        android:hint="请输入端口，例如8080"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

那么我们如何加入到AlertDialog中呢

通过使用 setview():设置自定义页面

View view=LayoutInflater.from(IntroductoryActivity.this).inflate(R.layout.ipconfig,null);
ip = view.findViewById(R.id.edit_ip);
port = view.findViewById(R.id.edit_port);
setview(view);

注意：在这里与我们平时拿控件的方法不同，一定要加上view. 再加上控件

否则会造成空指针报错

以下附上全部代码示例（该实例是一个引导页，其中涉及到数据存储的知识点，可以看我的其他博客）

MainActivity：默认代码，无任何功能

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

MainActivity对应的Layout文件：同样为默认代码

<?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!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

GuideActivity ：引导页主界面

package com.example.myapplication;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.Toast;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;

import java.util.ArrayList;
import java.util.List;


public class GuideActivity extends AppCompatActivity {

    private ViewPager vp;
    private List<ImageView> imageViews;
    private int[] imgs = {R.drawable.y0, R.drawable.y1, R.drawable.y2, R.drawable.y3};
    private Button btn, btn2;
    private EditText ed_ip, ed_port;
    private ImageView[] dotViews;
    private GuideAdapter adapter;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getSupportActionBar().hide();
        setContentView(R.layout.activity_guide);
        vp = findViewById(R.id.guide_vp);
        btn = findViewById(R.id.guide_btn);
        btn2 = findViewById(R.id.guide_btn2);

        //初始化图片
        initImgs();
        //初始化底部圆点指示器
        initDots();
        adapter = new GuideAdapter(imageViews);
        vp.setAdapter(adapter);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SharedPreferences.Editor editor = getSharedPreferences("data", MODE_PRIVATE).edit();
                editor.putString("isFirst", "1");
                editor.apply();
                Intent intent = new Intent(GuideActivity.this, MainActivity.class);
                startActivity(intent);
                finish();
            }
        });
        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                View view = LayoutInflater.from(GuideActivity.this).inflate(R.layout.ipconfig, null);
                ed_ip = view.findViewById(R.id.ed_ip);
                ed_port = view.findViewById(R.id.ed_port);

                AlertDialog.Builder builder = new AlertDialog.Builder(GuideActivity.this);
                SharedPreferences sp = getSharedPreferences("demo1", MODE_PRIVATE);
                ed_ip.setText(sp.getString("ip", ""));
                ed_port.setText(sp.getString("port", ""));
                builder.setTitle("端口设置")
                        .setView(view)

                        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {

                                SharedPreferences.Editor editor = sp.edit();
                                editor.putString("ip", ed_ip.getText().toString());
                                editor.putString("port", ed_port.getText().toString());
                                editor.apply();
                            }
                        })
                        .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(GuideActivity.this, "取消端口设置", Toast.LENGTH_SHORT).show();
                            }
                        })
                        .show();


            }
        });
        vp.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                for (int i = 0; i < dotViews.length; i++) {
                    if (position == i) {
                        dotViews[i].setImageResource(R.drawable.guide_selector);
                    } else {
                        dotViews[i].setImageResource(R.drawable.guide_white);
                    }

                    if (position == dotViews.length - 1) {
                        btn.setVisibility(View.VISIBLE);
                        btn2.setVisibility(View.VISIBLE);
                    } else {
                        btn.setVisibility(View.GONE);
                        btn2.setVisibility(View.GONE);
                    }
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

    }

    /**
     * 初始化底部圆点指示器
     */
    private void initDots() {
        LinearLayout layout = findViewById(R.id.guide_ll);
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(20, 20);
        params.setMargins(10, 0, 10, 0);
        dotViews = new ImageView[imgs.length];
        for (int i = 0; i < imageViews.size(); i++) {
            ImageView imageView = new ImageView(this);
            imageView.setLayoutParams(params);
            imageView.setImageResource(R.drawable.guide_white);
            if (i == 0) {
                imageView.setImageResource(R.drawable.guide_selector);
            } else {
                imageView.setImageResource(R.drawable.guide_white);
            }
            dotViews[i] = imageView;
            final int finalI = i;
            dotViews[i].setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    vp.setCurrentItem(finalI);
                }
            });
            layout.addView(imageView);
        }
    }

    /**
     * 初始化图片
     */
    private void initImgs() {
        ViewPager.LayoutParams params = new ViewPager.LayoutParams();
        imageViews = new ArrayList<ImageView>();
        for (int i = 0; i < imgs.length; i++) {
            ImageView imageView = new ImageView(this);
            imageView.setLayoutParams(params);
            imageView.setImageResource(imgs[i]);
            imageView.setScaleType(ImageView.ScaleType.FIT_XY);
            imageViews.add(imageView);
        }
    }


}

activity_guide.xml：引导页layout文件

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


    <androidx.viewpager.widget.ViewPager
        android:id="@+id/guide_vp"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <LinearLayout
        android:id="@+id/guide_ll"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="100dp"
        android:orientation="horizontal" />

    <Button
        android:id="@+id/guide_btn"
        android:layout_width="100dp"
        android:layout_height="40dp"
        android:layout_above="@id/guide_ll"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="10dp"
        android:background="#2990E3"
        android:text="开始体验"
        android:textColor="#ffffff"
        android:visibility="invisible" />
    <Button
        android:id="@+id/guide_btn2"
        android:layout_width="100dp"
        android:layout_height="40dp"
      android:layout_alignRight="@id/guide_vp"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="10dp"
        android:background="#2990E3"
        android:text="端口设置"
        android:textColor="#ffffff"
        android:visibility="invisible"/>

</RelativeLayout>

GuideAdapter ：引导页适配器

package com.example.myapplication;



import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import androidx.annotation.NonNull;
import androidx.viewpager.widget.PagerAdapter;

import java.util.List;

public class GuideAdapter extends PagerAdapter {

    private final List<ImageView> imageViews;

    public GuideAdapter(List<ImageView> imageViews) {
        this.imageViews= imageViews;
    }

    /**
     * 获取当前要显示对象的数量
     */
    @Override
    public int getCount() {
        return imageViews.size();
    }

    /**
     * 判断是否用对象生成界面
     */
    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
        return view== o;
    }

    /**
     * 从ViewGroup中移除当前对象
     */
    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView(imageViews.get(position));

    }
    /**
     * 当前要显示的对象
     */
    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        container.addView(imageViews.get(position));
        return imageViews.get(position);
    }

}

ipconfig.xml：ip配置界面

<?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"
    android:orientation="vertical">

    <EditText
        android:id="@+id/ed_ip"
        android:layout_width="269dp"
        android:layout_height="83dp"
        android:layout_marginTop="28dp"
        android:layout_marginEnd="68dp"
        android:ems="10"
        android:gravity="center"
        android:hint="请输入IP，例如192.168.1.1"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/ed_port"
        android:layout_width="261dp"
        android:layout_height="86dp"
        android:layout_marginTop="120dp"
        android:layout_marginEnd="72dp"
        android:ems="10"
        android:gravity="center"
        android:hint="请输入端口，例如8080"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

guide_white.xml：未选择白色圆点

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <size android:height="20dp" android:width="20dp"/>
    <solid android:color="#fff"/>
</shape>

guide_selector.xml ：选择蓝色圆点

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <size android:height="20dp" android:width="20dp"/>
    <solid android:color="#0687ED"/>
</shape>

引导页的4张图片自己加就可以了

android：对话框AlertDialog

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