Activity中获取view的高和宽为0时的解决方法

在activity中可以调用View.getWidth、View.getHeight()、View.getMeasuredWidth() 、View.getgetMeasuredHeight()来获得某个view的宽度或高度,但是在onCreate()、onStrart()、onResume()方法中会返回0,这是应为当前activity所代表的界面还没显示出来没有添加到WindowPhone的DecorView上或要获取的view没有被添加到DecorView上或者该View的visibility属性为gone 或者该view的width或height真的为0  所以只有上述条件都不成立时才能得到非0的width和height  

所以要想获取到的width和height为真实有效的 则有以下方法

1.在该View的事件回调里使用  这时候该view已经被显示即被添加到DecorView上  如点击事件  触摸事件   焦点事件等

[java]  view plain copy
  1. View view=findViewById(R.id.tv);  
  2.     view.setOnClickListener(new OnClickListener() {  
  3.           
  4.         @Override  
  5.         public void onClick(View v) {  
  6.             int width = v.getWidth();  
  7.         }  
  8.     });  

2.在activity被显示出来时即添加到了DecorView上时获取宽和高如onWindowFocusChanged() 回调方法

[java]  view plain copy
  1. @Override  
  2.   public void onWindowFocusChanged(boolean hasFocus) {  
  3.     View iv1 = findViewById(R.id.iv1);  
  4. View iv2=findViewById(R.id.iv2);  
  5. String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+"  measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();  
  6. String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+"  measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();  
  7. i("onWindowFocusChanged() "+msg1);  
  8. i("onWindowFocusChanged() "+msg2);  
  9.     super.onWindowFocusChanged(hasFocus);  
  10.   }  

3.或在onResume方法最后开线程300毫秒左右后获取宽和高   因为onResume执行完后300毫秒后 界面就显示出来了  

当然地2种和地3种方法要保证获取宽高的view是在setContentView时设进去的View或它的子View

[java]  view plain copy
  1. view.postDelayed(new Runnable() {  
  2.               
  3.             @Override  
  4.             public void run() {  
  5.                 View iv1 = findViewById(R.id.iv1);  
  6.                 View iv2=findViewById(R.id.iv2);  
  7.                 String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+"  measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();  
  8.                 String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+"  measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();  
  9.                 i("onWindowFocusChanged() "+msg1);  
  10.                 i("onWindowFocusChanged() "+msg2);  
  11.             }  
  12.         }, 300);  


4.在onCreate()或onResume()等方法中需要获取宽高时使用getViewTreeObserver().addOnGlobalLayoutListener()来为view加回调在回调里获得宽度或者高度获取完后让view删除该回调

[java]  view plain copy
  1. view.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {  
  2.           
  3.         @Override  
  4.         public void onGlobalLayout() {  
  5.             view.postDelayed(new Runnable() {  
  6.                   
  7.                 @Override  
  8.                 public void run() {  
  9.                     View iv1 = findViewById(R.id.iv1);  
  10.                     View iv2=findViewById(R.id.iv2);  
  11.                     String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+"  measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();  
  12.                     String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+"  measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();  
  13.                     i("onWindowFocusChanged() "+msg1);  
  14.                     i("onWindowFocusChanged() "+msg2);  
  15.                 }  
  16.             }, 300);  
  17.         }  
  18.     });  

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