Java Hello World例子和添加按钮事件与功能

新建android工程，然后默认“下一步”即可完成创建；

2.添加Button

3.在src的MainActivity.java添加以下红色代码

import android.support.v7.app.ActionBarActivity;import android.support.v7.app.ActionBar;import android.support.v4.app.Fragment;import android.content.Intent;import android.os.Bundle;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.Button;import android.widget.TextView;import android.widget.Toast;import android.os.Build;

public class MainActivity extends ActionBarActivity {PRivate Button mButton;

@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);

if (savedInstanceState == null) {getSupportFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();} mButton=(Button)findViewById(R.id.button1); mButton.setOnClickListener(buttonOnClickListener); }private OnClickListener buttonOnClickListener = new OnClickListener(){@Overridepublic void onClick(View v) { Toast.makeText(getapplicationContext(), "点击按钮事件", Toast.LENGTH_SHORT).show();}};