setImageResource導致NULL指針異常

Question

我有一個對話框。有一個Imageview。我越來越NullPointerException同時設定圖像programically。這是我的對話框

 LayoutInflater inflater = Tutorial7.this.getLayoutInflater(); 
    DialogInterface.OnClickListener dialogClickListener = new DialogInterface.OnClickListener() { 
     @Override 
     public void onClick(DialogInterface dialog, int which) { 
      switch (which){ 
      case DialogInterface.BUTTON_POSITIVE: 
       //Yes button clicked 
       break; 

      case DialogInterface.BUTTON_NEGATIVE: 
       //No button clicked 
       break; 
      } 
     } 
    }; 

    AlertDialog.Builder builder = new AlertDialog.Builder(Tutorial7.this); 
    builder.setView(inflater.inflate(R.layout.dialogview, null)); 
    myimage = (ScaleImageView)findViewById(R.id.dialogboximage); 
    String mypath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/target.jpg"; 
    File mydir = new File(mypath); 
    try 
    { 
     if(mydir.exists()) 
      System.out.println("True"); 
     else 
      System.out.println("False"); 
    } 
    finally{ 
    System.out.println("The file i am trying to decode:-"+Environment.getExternalStorageDirectory().getAbsolutePath() + "/target.jpg"); 
    } 

    /* I am getting error in this line*/myimage.setImageResource(R.drawable.button_chair_selected); 
    builder.setMessage("Are you sure?").setPositiveButton("Yes", dialogClickListener) 
     .setNegativeButton("No", dialogClickListener).show(); 

dialogbox.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:orientation="vertical" 
android:weightSum="2"> 

<com.myapp.myarapp.ScaleImageView 
    android:id="@+id/dialogboximage" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:layout_weight="2" 
    /> 

</LinearLayout> 

Answer 1

更改此

myimage = (ScaleImageView)findViewById(R.id.dialogboximage); 

到

View v= inflater.inflate(R.layout.dialogview, null); 
builder.setView(v); 
myimage = (ScaleImageView)v.findViewById(R.id.dialogboximage);