Android开发手记(7) 按钮类控件的使用

1、点击Button改变页面背景色

　　通过Button改变页面背景色，首先新建相应的对象，让后绑定到Layout上的元素。

  final RelativeLayout layout = (RelativeLayout)this.findViewById(R.id.layout);
  final Button btnRed = (Button)this.findViewById(R.id.btnRed);

　　然后向新建的按钮增加单机事件。

 btnRed.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                layout.setBackgroundColor(Color.RED);
                ((Button)view).setText("Is Red");
            }
        });

　　完整代码：

 public class MainActivity extends AppCompatActivity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         this.setTitle("Button");
         setContentView(R.layout.activity_main);

         final RelativeLayout layout = (RelativeLayout)this.findViewById(R.id.layout);
         final Button btnRed = (Button)this.findViewById(R.id.btnRed);
         final Button btnGreen = (Button)this.findViewById(R.id.btnGreen);
         final Button btnBlue = (Button)this.findViewById(R.id.btnBlue);

         btnRed.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) {
                 btnGreen.setText("Green");
                 btnBlue.setText("Blue");
                 layout.setBackgroundColor(Color.RED);
                 ((Button)view).setText("Is Red");
             }
         });
         btnGreen.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) {
                 btnRed.setText("Red");
                 btnBlue.setText("Blue");
                 layout.setBackgroundColor(Color.GREEN);
                 ((Button)view).setText("Is Green");
             }
         });
         btnBlue.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) {
                 btnRed.setText("Red");
                 btnGreen.setText("Green");
                 layout.setBackgroundColor(Color.BLUE);
                 ((Button)view).setText("Is Blue");
             }
         });

     }
 }

MainActivity.java

2、CheckBox状态获取

　　要获取CheckBox状态，只需要设置OnCheckedChangeListener()即可。

 CheckBox chkBox = (CheckBox) findViewById(R.id.chkFootball);
 chkFootball.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
                 if (b) strFootball = "Football";
                 else strFootball = "";
                 tvResult.setText(strFootball + " " + strBasketball);
             }
         });

　　完整代码为：

 public class MainActivity extends AppCompatActivity {

     private String strFootball = "";
     private String strBasketball = "";
     private TextView tvResult ;
     private CheckBox chkFootball;
     private CheckBox chkBasketball;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 //        this.setTitle("Button");
         setContentView(R.layout.activity_main);
         tvResult = (TextView) findViewById(R.id.tvResult);
         chkFootball = (CheckBox) findViewById(R.id.chkFootball);
         chkBasketball = (CheckBox) findViewById((R.id.chkBasketball));

         chkFootball.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
                 if (b) strFootball = "Football";
                 else strFootball = "";
                 tvResult.setText(strFootball + " " + strBasketball);
             }
         });

         chkBasketball.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
                 if (b) strBasketball = "Basketball";
                 else strBasketball = "";
                 tvResult.setText(strFootball + " " + strBasketball);
             }
         });
     }

 }

MainActivity.java

　　

3、RadioButton与RadioGroup

　　要获取RadioGroup内RadioButton的选择状态，为RadioGroup添加选择事件即可。

 rGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(RadioGroup radioGroup, int i) {
                 // TODO
             }
         });

　　首先在RadioGroup内创建两个RadioButton

 <RadioGroup
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_below="@+id/textView"
         android:layout_alignParentLeft="true"
         android:layout_alignParentStart="true"
         android:id="@+id/rGroup">

         <RadioButton
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:text="男"
             android:id="@+id/rbMale"
             android:checked="false" />

         <RadioButton
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:text="女"
             android:id="@+id/rbFemale"
             android:checked="false" />

     </RadioGroup>

　　然后，为RadioGroup设置OnCheckedChangeListener()

  rGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(RadioGroup radioGroup, int i) {
                 if(i==rbMale.getId()) {
                     result.setText("你的性别是：男");
                 }
                 else if(i==rbFemale.getId()){
                     result.setText("你的性别是：女");
                 }
             }
         });

　　完整代码：

 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.widget.CheckBox;
 import android.widget.CompoundButton;
 import android.widget.RadioButton;
 import android.widget.RadioGroup;
 import android.widget.TextView;

 public class MainActivity extends AppCompatActivity {

         private TextView result;
         private RadioButton rbMale;
         private RadioButton rbFemale;
         private RadioGroup rGroup;

         @Override
         protected void onCreate(Bundle savedInstanceState) {
             super.onCreate(savedInstanceState);
 //        this.setTitle("Button");
             setContentView(R.layout.activity_main);

             result = (TextView)findViewById(R.id.textView);
             rbMale = (RadioButton)findViewById(R.id.rbMale);
             rbFemale = (RadioButton)findViewById(R.id.rbFemale);
             rGroup = (RadioGroup)findViewById(R.id.rGroup);

             rGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(RadioGroup radioGroup, int i) {
                 if(i==rbMale.getId()) {
                     result.setText("你的性别是：男");
                 }
                 else if(i==rbFemale.getId()){
                     result.setText("你的性别是：女");
                 }
             }
         });

     }

 }

MainActivity.java