Android development-Android common components-Button button

4.3 Button (button)

• The Button control inherits from TextView and has the properties of TextView.
• Introduction to StateListDrawable

StateListDrawable is a kind of Drawable resource, which can set different image effects according to different states, the key node <selector>, we only need to set the background property of Button to this drawable resource, and then we can easily realize different display when pressing the button. Button color or background!

attribute name	illustrate
drawable	The referenced Drawable bitmap, we can put it at the front, which means the normal state of the component~
state_focused	Whether to get the focus
state_window_focused	Whether to get the window focus
state_enabled	Whether the control is available
state_checkable	Whether the control can be checked
state_checked	Whether the control is checked
state_selected	Whether the control is selected, for the case with a scroll wheel
state_pressed	Whether the control is pressed
state_active	Whether the control is active
state_single	When the control contains multiple child controls, determine whether to display only one child control
state_first	When the control contains multiple child controls, determine whether the first child control is displayed
state_middle	When the control contains multiple sub-controls, determine whether the middle sub-control is displayed
state_last	When the control contains multiple child controls, determine whether the last child control is displayed

 

 Example:

Create a new xml file btn_bg1.xml under the drawable folder.

 

 btn_bg1.xml:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/dark_gray" android:state_pressed="true"/>　　//控件被按下时变成深灰
    <item android:drawable="@color/lawn_green" android:state_enabled="false"/>　　　　//控件不可用时变成绿色
    <item android:drawable="@color/purple_200"/>　　　　//控件平常时显示浅紫色
</selector>

 

 Create botton.xml in the layout folder:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#eeeeee"
    android:paddingTop="50dp">

    <Button
        android:id="@+id/btnOne"
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:background="@drawable/btn_bg1"
        android:text="按钮"
        android:textColor="@color/white"
        android:textSize="20sp"
        android:textStyle="bold"/>
    <Button
        android:id="@+id/btnTwo"
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:text="按钮不可用"
        android:textColor="@color/black"
        android:textSize="20sp"
        android:textStyle="bold"/>


</LinearLayout>

MainActivity.java:

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;


public class MainActivity extends AppCompatActivity {

    private Button btnOne,btnTwo;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.button);
        btnOne = (Button) findViewById(R.id.btnOne);
        btnTwo = (Button) findViewById(R.id.btnTwo);
        btnTwo.setOnClickListener(new View.OnClickListener(){   //按钮绑定事件
            @Override
            public void onClick(View v){
                if (btnTwo.getText().toString().equals("按钮不可用")){
                    btnOne.setEnabled(false);
                    btnTwo.setText("按钮可用");
                }else {
                    btnOne.setEnabled(true);
                    btnTwo.setText("按钮不可用");
                }
            }
        });

    }
}