提示框（二）

1.  MainActivity

public class MainActivity extends AppCompatActivity {
    private Button mybutton = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.mybutton = (Button) super.findViewById(R.id.mybutton);
        this.mybutton.setOnClickListener(new OnClickListenerImp());

    }

    private class OnClickListenerImp implements OnClickListener {
        @Override
        public void onClick(View v) {
            MainActivity.this.exitDialog();
        }
    }

    private void exitDialog() {
        Dialog dialog =  new AlertDialog.Builder(MainActivity.this)
                .setTitle("program back?")
                .setMessage("are you sure to exit this program?")
                .setPositiveButton("sure",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                MainActivity.this.finish();    //end of program
                            }
                        }).setNegativeButton("cancel",     //add cancel button
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                            }
                        }).create();   //create Dialog
        dialog.show();   //show Dialog
    }
}

2.  activity_main.xml

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/mytext"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="60dp"
    android:text="hello" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="delete"
    android:id="@+id/mybutton"
    android:layout_below="@+id/mytext"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="55dp" />