SayHello

1.activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:gravity="center"
    android:background="@drawable/bg"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/prompt" />

    <EditText
        android:id="@+id/name"
        android:layout_width="198dp"
        android:layout_height="wrap_content"
        android:inputType="text"
        android:textSize="20sp" />

    <Button
        android:id="@+id/clickButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/click" />

</LinearLayout>

2.MainActivity.java

package cn.bzu.sayhello;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {
 private Button clickButton;
 private EditText nameText;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  clickButton = (Button) findViewById(R.id.clickButton);
  nameText = (EditText) this.findViewById(R.id.name);
  //绑定事件源和事件处理者 委托处理
  clickButton.setOnClickListener(new ClickHandler());

 }

 //事件处理类
 private class ClickHandler implements OnClickListener {

  @Override
  public void onClick(View v) {
   Toast.makeText(MainActivity.this,
     "你好" + nameText.getText().toString(), Toast.LENGTH_LONG)
     .show();
  }

 }

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

}