sayHellow --android开发

布局： 
  
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:background="@drawable/dog"
    tools:context=".MainActivity" > 
  
    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="点击" /> 
  
    <EditText
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/button1"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="48dp"
        android:ems="10"
        android:textSize="18sp" /> 
  
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/name"
        android:layout_alignLeft="@+id/name"
        android:layout_marginBottom="14dp"
        android:text="请输入你的姓名"
        android:textSize="22sp" /> 
  
</RelativeLayout> 

  

第一种方法： 
  
package bzu.gezi.com.example.sayhellow; 
  
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); 
        init(); 
        clickbutton.setOnClickListener(new clickHandler()); 
          
    } 
    private void init(){ 
        clickbutton=(Button)this.findViewById(R.id.button1); 
        nametext=(EditText) findViewById(R.id.name); 
          
          
    } 
      
    private class clickHandler implements OnClickListener{ 
        @Override 
        public void onClick(View v) { 
            // TODO Auto-generated method stub 
            String name=nametext.getText().toString(); 
            Toast.makeText(MainActivity.this, "你好"+name, 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; 
    } 
  
      
  
} 
  
第二种方法： 
  
package cn.bzu.case1; 
  
import android.os.Bundle; 
import android.app.Activity; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ImageView; 
import android.widget.Toast; 
import android.support.v4.app.NavUtils; 
  
public class MainActivity extends Activity { 
    private Button clickButton; 
    private EditText nameText; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
       /* ImageView imageView=new ImageView(this); 
        imageView.setImageResource(R.drawable.bg); 
        setContentView(imageView);*/ 
        setContentView(R.layout.activity_main); 
        initialComponents();  
        //绑定事件源和事件处理者 
        //clickButton.setOnClickListener(new ClickHandler());匿名对象 
        clickButton.setOnClickListener(new OnClickListener(){ 
  
            @Override 
            public void onClick(View v) { 
                String name=nameText.getText().toString(); 
                Toast.makeText(MainActivity.this, "你好"+name, Toast.LENGTH_LONG).show(); 
            } 
              
        }); 
          
    } 
      
    private void initialComponents(){ 
        clickButton=(Button) this.findViewById(R.id.clickButton); 
        nameText=(EditText) findViewById(R.id.name); 
    } 
    @Override 
第三种方法 
package cn.bzu.case1; 
  
  
import android.os.Bundle; 
  
import android.app.Activity; 
  
import android.view.Menu; 
  
import android.view.MenuItem; 
  
import android.view.View; 
  
import android.view.View.OnClickListener; 
  
import android.widget.Button; 
  
import android.widget.EditText; 
  
import android.widget.ImageView; 
  
import android.widget.Toast; 
  
import android.support.v4.app.NavUtils; 
  
  
public class MainActivity extends Activity { 
  
    private EditText nameText; 
  
    @Override 
  
    public void onCreate(Bundle savedInstanceState) { 
  
        super.onCreate(savedInstanceState); 
  
        setContentView(R.layout.activity_main); 
  
        initialComponents();  
  
    } 
  
      
  
    public void clickHandler(View view){ 
  
     String name=nameText.getText().toString(); 
  
Toast.makeText(MainActivity.this, "你好"+name, Toast.LENGTH_LONG).show(); 
  
    } 
  
    private void initialComponents(){ 
  
        nameText=(EditText) findViewById(R.id.name); 
  
    } 
  
    @Override 
  
    public boolean onCreateOptionsMenu(Menu menu) { 
  
        getMenuInflater().inflate(R.menu.activity_main, menu); 
  
        return true; 
  
    } 
  
  
      
  
} 
  
  
   
  
  
  
    public boolean onCreateOptionsMenu(Menu menu) { 
        getMenuInflater().inflate(R.menu.activity_main, menu); 
        return true; 
    } 
  
      
} 
  
  
 <Button android:id="@+id/clickButton" android:layout_centerHorizontal="true" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/name" android:onClick="clickHandler" android:text="@string/clickbutton" />