android 监听联系人数据库

package com.test.contentobserver; import android.app.Activity; import android.database.ContentObserver; import android.os.Bundle; import android.provider.Contacts.People; public class TestContentObserver extends Activity {     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);         this.getApplicationContext().getContentResolver().registerContentObserver (People.CONTENT_URI, true, contentObserver);     }     private class MyContentObserver extends ContentObserver {         public MyContentObserver() {             super(null);         }         @Override         public void onChange(boolean selfChange) {             super.onChange(selfChange);         }     }     MyContentObserver contentObserver = new MyContentObserver(); }