看代码学Android ：如何显示对话框MessageBox?

package com.test;

//import java.net.URISyntaxException;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class TestActivity1 extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button btn = (Button) this.findViewById(R.id.button1);
        btn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                // Show a hint message box and auto disappear after timeout
                Toast.makeText(getApplicationContext(), "Hello Android, I am coming....",
                         Toast.LENGTH_LONG).show();
            }
        });
    }
}

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搞个有按钮的对话框，点击button退出activity.

Dialog dlg = new AlertDialog.Builder(TestActivity1 .this)
                .setMessage(R.string.hello)
                .setCancelable(false)   // disable cancel action, hardware back button
                .setPositiveButton(R.string.OK,
                        new DialogInterface.OnClickListener() {

                            public void onClick(DialogInterface dialog, int which) {
                                 TestActivity1.this.finish();
                            }

                        }).create();


            dlg.show();