語法錯誤的標記「如果」，無效AnnotationName

Question

嗨我正在使用android和我試圖把一個「if」語句圍繞這個類，但我得到錯誤「令牌上的語法錯誤」如果「，無效AnnotationName 「 有幫助嗎？

private String str = "0"; 
if(str == 0){ 
    public boolean onKeyDown(int keyCode, KeyEvent event) 
    { 

     //Handle the back button 
     if(keyCode == KeyEvent.KEYCODE_BACK) 
     { 
      //Ask the user if they want to quit 
      new AlertDialog.Builder(this) 
      .setIcon(android.R.drawable.ic_dialog_alert) 
      .setTitle("Coupon") 
      .setMessage("Do you want a coupon texted to you?") 
      .setPositiveButton("YES!", new DialogInterface.OnClickListener() 
      { 
       @Override 
       public void onClick(DialogInterface dialog, int which) 
       { 
        //Stop the activity 
        Toast.makeText(buttonOne.this, "Great! You'll get one in just a couple of minutes.", Toast.LENGTH_LONG).show(); 
        finish(); 
       } 
      }) 
      .setNegativeButton("Not now", new DialogInterface.OnClickListener() 
      { 
       @Override 
       public void onClick(DialogInterface dialog, int which) 
       { 
        //Stop the activity 
        finish(); 
       } 
      }) 
      .show();   
      return true; 
     } 
     else 
     { 
      return super.onKeyDown(keyCode, event); 
     } 

    } 
} 
else 
{} 

Answer 1

您不能將控制結構（如if語句）放在函數之外。

Answer 2

必須使用equals字符串方法：

if (str.equals("0")){ 
    ... 
}