通過編程方式更改背景

Question

我是一個完整的android新手，所以對我來說很容易。 我有這個代碼，當你點擊一個按鈕時改變背景，但是我想每隔10秒改變背景，並且我想在文件img1.png，img2.png和img3.png之間切換，並且當循環完成時重新開始。提前致謝。 下面是代碼： 在 'MainActivity.java'

package lucas.app_2001; 

import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.LinearLayout; 


public class MainActivity extends Activity { 
    /** Called when the activity is first created. */ 
    Button button; 
    LinearLayout mainLayout; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     mainLayout=(LinearLayout)findViewById(R.id.myLayout); 
     button=(Button)findViewById(R.id.button1); 
     button.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View arg0) { 
       mainLayout.setBackgroundResource(R.drawable.yellowgradient); 
      } 
     }); 
    } 
} 

'MainActivity.xml'：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/myLayout" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" > 

    <Button 
     android:id="@+id/button1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentTop="true" 
     android:layout_marginLeft="64dp" 
     android:layout_marginTop="71dp" 
     android:text="Shout!" /> 

</LinearLayout> 

Answer 1

你可以這樣說：

private Handler mHandler; 
private Runnable mRunnable; 
private int i = 0; 

MainActivity.java：

public class MainActivity extends Activity { 
    /** Called when the activity is first created. */ 
    Button button; 
    LinearLayout mainLayout; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     mainLayout=(LinearLayout)findViewById(R.id.myLayout); 
     button=(Button)findViewById(R.id.button1); 
     button.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View arg0) { 
       mainLayout.setBackgroundResource(R.drawable.yellowgradient); 
      } 
     }); 

     mHandler = new Handler(); 
     mRunnable = new Runnable(){ 
     @Override 
     public void run() { 
      i++; 
      if(i==1){ 
      mainLayout.setBackgroundResource(R.drawable.image_one); 
       }else if(i==2){ 
      mainLayout.setBackgroundResource(R.drawable.image_two); 
       }else if(i==3){ 
      mainLayout.setBackgroundResource(R.drawable.image_three); 
       i ==0; 
       } 

      mHandler.postDelayed(mRunnable , 10000); 
      } 
     }; 
     mHandler .post(mRunnable); 
    } 
} 

上onStop（）：

if(mHandler!=null){ 
    mHandler.removeCallbacks(mRunnable); 
} 

完成

Answer 2

使用while循環重複。

要延遲並保持10秒鐘嘗試這樣的事：

//wait 10 seconds 
     Button.postDelayed(new Runnable() { 

      @Override 
      public void run() { 
       Button.setClickable(true);       
      } 
     }, 10000);