Android對話框幫助！

Question

我有一個問題，我希望你們能幫助我！

此代碼創建一個對話框，並在對話框中顯示一個按鈕和一個seekbar。

當我設置seekbar setonseekbarchangelistener我得到一個Nullpointerexception錯誤。我不知道爲什麼！ （取消註釋seekbar.setOnSeekBarChangeListener（本），以獲得錯誤）

public class seekActivity extends Activity implements OnClickListener, OnSeekBarChangeListener { 
     SeekBar seekbar; 
     Button button; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     //set up main content view 
     setContentView(R.layout.main); 
     //this button will show the dialog 
     Button button1main = (Button) findViewById(R.id.Button01main); 


     button1main.setOnClickListener(this); 

    } 
     public void onClick(View v) { 
       //set up dialog 
       Dialog dialog = new Dialog(this); 
       dialog.setContentView(R.layout.maindialog); 
       dialog.setTitle("This is my custom dialog box"); 
       dialog.setCancelable(true); 
       button = (Button) dialog.findViewById(R.id.Button01); 
       seekbar = (SeekBar) findViewById(R.id.seekBar1); 
       //seekbar.setOnSeekBarChangeListener(this); 
       dialog.show(); 

     } 
     @Override 
     public void onProgressChanged(SeekBar seekBar, int progress, 
       boolean fromUser) { 
      // TODO Auto-generated method stub 

     } 
     @Override 
     public void onStartTrackingTouch(SeekBar seekBar) { 
      // TODO Auto-generated method stub 

     } 
     @Override 
     public void onStopTrackingTouch(SeekBar seekBar) { 
      // TODO Auto-generated method stub 

     }; 


      } 

Answer 1

使用這段代碼，由ID找到seekBar1。

seekbar = (SeekBar) dialog.findViewById(R.id.seekBar1);