[Android] check APP exist or not

以VLC APP為例

private View.OnClickListener marketListener=new View.OnClickListener() {
  @Override
  public void onClick(View v) {
   if(isPackageExisted("org.videolan.vlc")){
       Toast.makeText(getApplicationContext(), "the APP is exist.", Toast.LENGTH_SHORT).show();        
   }else{             
               // 尋找某個應用程式  
               Uri uri = Uri.parse("market://search?q=pname:org.videolan.vlc"); 
               Intent it = new Intent(Intent.ACTION_VIEW, uri);  
               startActivity(it);  
   }
  }
 }; 
 public boolean isPackageExisted(String targetPackage){
     PackageManager pm=getPackageManager();
     try {
      PackageInfo info=pm.getPackageInfo(targetPackage,PackageManager.GET_META_DATA);
         } catch (NameNotFoundException e) {
      return false;
      }
      return true;
 }