Activity의 onCreate() 내에서 setContentView 이후에 직접 작성한 CustomView를 

findViewById() 로 찾아내어 제어를 하려고 하나 null 값이 들어오고 있습니다. 

당최 어디가 잘못된 것인지 고심고심 하다가 질문 올립니다.

능력자분들~! 답변 좀 부탁드립니다.

(SDK 1.6 Donut)

main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
 <TextView  
    android:layout_width="fill_parent" 
    android:layout_height="10dp" 
    android:text="@string/hello" />
 <com.test.MapCanvas
  android:id="@+id/map_canvas"
  android:layout_width="fill_parent"
  android:layout_height="100dp"
     android:focusable="true" 
  android:clickable="true" />
</LinearLayout>

MapCanvas.java
package com.test;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.View;

public class MapCanvas extends View {         
     // ...        
    public MapCanvas(Context context) {
     super(context);
     initialize();
    }
    
    public MapCanvas(Context context, AttributeSet attrs) {
     super(context);
     initialize();
    }
    
    private void initialize() {
        // ...
      }


 @Override
    protected void onDraw(Canvas canvas) {
        // ...
    }     
}



Activity.java
package com.test;

import android.app.Activity;
import android.os.Bundle;
import com.test.MapCanvas;

public class Test113 extends Activity {
    /** Called when the activity is first created. */
 private MapCanvas mapCanvas;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mapCanvas = (MapCanvas)this.findViewById(R.id.map_canvas); // null 값이 들어가는 곳.
    }
}