点击按钮后显示AlertDialog

想用一个单选按钮显示对话框，但是点击按钮对话框却不显示。

代码如下，不知道哪里出现错误。

谢谢

public class MainPage extends Activity{
Button start;
private static final int DIALOG_SINGLE_CHOICE = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mainpage);
    start = (Button) findViewById(R.id.start);
    start.setBackgroundResource(R.drawable.read);
    start.setOnClickListener(new View.OnClickListener() {
        @SuppressWarnings("deprecation")
        public void onClick(View v) {
            showDialog(DIALOG_SINGLE_CHOICE );
        }
    });
}
@Override
@Deprecated
protected Dialog onCreateDialog(int id) {
    id = DIALOG_SINGLE_CHOICE;
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Choose your option");
    builder.setSingleChoiceItems(R.array.Baani, 0, new OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            // TODO Auto-generated method stub
        }
    })
    .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {

                    /* User clicked Yes so do some stuff */
                }
            })
            .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {

                    /* User clicked No so do some stuff */
                }
            })
           .create();
    return super.onCreateDialog(id);
        }   
  }
}

public class MainActivity extends Activity implements OnClickListener{
private Button button;
private static final int DIALOG_SINGLE_CHOICE = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button  = (Button) findViewById(R.id.button);
    button.setOnClickListener(this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.button:
        showDialog(DIALOG_SINGLE_CHOICE);
        break;

    default:
        break;
    }
}

@Override
@Deprecated
protected Dialog onCreateDialog(int id) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Choose your option");
    builder.setSingleChoiceItems(R.array.Baani, 0, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            // TODO Auto-generated method stub
        }

    }).setPositiveButton("OK", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {

            /* User clicked Yes so do some stuff */
        }
    }).setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {

            /* User clicked No so do some stuff */
        }
    }).create().show();
    return super.onCreateDialog(id);
}

}

Dialog只create()；没有show()的动作吧

start.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
           new AlertDialog.Builder(this)
        .setTitle("请选择！")
        .setMessage("确定退出吗？")
        .setPositiveButton("确定",
        new android.content.DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog,int which) {
            dialog.dismiss();
                                              }
                                              })
        .setNegativeButton("取消",
            new android.content.DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog,int which) {
                dialog.dismiss();
                                                   }
                        }).show();
        }
    });