android开发 点击按钮弹出对话框的简单实现

package com.example.lenovo.duihuakuang;

import android.content.DialogInterface;
import android.app.AlertDialog;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initEvent();
    }
    private void initEvent() {
        findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
            showDialog();
            }
        });
    }

    private void showDialog(){
        AlertDialog.Builder builder=new AlertDialog.Builder(this);
        builder.setIcon(R.drawable.asdf);
        builder.setTitle("提示");
        builder.setMessage("1234！");
        builder.setPositiveButton("5678",
                new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {

                    }
                });
        AlertDialog dialog=builder.create();
        dialog.show();

        }
    }