Android实战教程第一篇之最简单的计算器

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:orientation="vertical" 
  android:layout_width="fill_parent" 
  android:layout_height="fill_parent" 
  > 
<EditText  
  android:id="@+id/factorOne" 
  android:layout_width="fill_parent"  
  android:layout_height="wrap_content"  
  /> 
<TextView  
  android:id="@+id/symbol" 
  android:layout_width="fill_parent"  
  android:layout_height="wrap_content"  
  /> 
<EditText  
  android:id="@+id/factorTwo" 
  android:layout_width="fill_parent"  
  android:layout_height="wrap_content"  
  /> 
<Button 
  android:id="@+id/calculate" 
  android:layout_width="fill_parent"  
  android:layout_height="wrap_content"  
  /> 
</LinearLayout> 

package mars.activity03; 
 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
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.TextView; 
//1.在Activity03当中，要声明四个控件 
//2.要为其中的两个控件设置显示的值 
//3.创建一个监听器类，监听按钮按下的动作 
//4.将监听器类的对象，绑定在按钮对象上 
public class Activity03 extends Activity { 
 /** Called when the activity is first created. */ 
 private EditText factorOne ; 
 private EditText factorTwo; 
 private TextView symbol; 
 private Button calculate; 
 @Override 
 public void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.main); 
  //根据控件的ID来取得代表控件的对象 
  factorOne = (EditText)findViewById(R.id.factorOne); 
  factorTwo = (EditText)findViewById(R.id.factorTwo); 
  symbol = (TextView)findViewById(R.id.symbol); 
  calculate = (Button)findViewById(R.id.calculate); 
  //为symbol和calculate设置显示的值 
//  symbol.setText("乘以"); 
//  calculate.setText("计算"); 
  symbol.setText(R.string.symbol);//这里通过引用的方式，去String文件中引用。保证了业务逻辑、视图、引用资源分开 
  calculate.setText(R.string.calculate); 
  //将监听器的对象绑定到按钮对象上面 
  calculate.setOnClickListener(new CalculateListener()); 
 } 
 //当客户点击MENU按钮的时候，调用该方法 
 @Override 
 public boolean onCreateOptionsMenu(Menu menu) { 
  menu.add(0, 1, 1, R.string.exit); 
  menu.add(0,2,2,R.string.about); 
  return super.onCreateOptionsMenu(menu); 
 } 
 //当客户点击菜单当中的某一个选项时，会调用该方法 
 @Override 
 public boolean onOptionsItemSelected(MenuItem item) { 
  if(item.getItemId() == 1){ 
   finish(); 
  } 
  return super.onOptionsItemSelected(item); 
 } 
 class CalculateListener implements OnClickListener{ 
 
  @Override 
  public void onClick(View v) { 
   //取得两个EditText控件的值 
   String factorOneStr = factorOne.getText().toString(); 
   String factorTwoStr = factorTwo.getText().toString(); 
   //将这两个值存放到Intent对象当中 
   Intent intent = new Intent(); 
   intent.putExtra("one",factorOneStr); 
   intent.putExtra("two",factorTwoStr); 
   intent.setClass(Activity03.this, ResultActivity.class); 
   //使用这个Intent对象来启动ResultActivity 
   Activity03.this.startActivity(intent); 
  } 
 } 
} 

package mars.activity03; 
 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.widget.TextView; 
//1.接受从Activity03当中所传递的值 
//2.计算两个值的积 
//3.将计算的结果显示在Activity上 
public class ResultActivity extends Activity{ 
 private TextView resultView; 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  // TODO Auto-generated method stub 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.result); 
  resultView = (TextView)findViewById(R.id.result); 
  //得到Intent对象当中的值 
  Intent intent = getIntent(); 
  String factorOneStr = intent.getStringExtra("one"); 
  String factorTwoStr = intent.getStringExtra("two"); 
  int factorOneInt = Integer.parseInt(factorOneStr); 
  int factorTwoInt = Integer.parseInt(factorTwoStr); 
  //计算两个值的积 
  int result = factorOneInt * factorTwoInt; 
  resultView.setText(result + ""); 
 } 
 
} 

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 <string name="hello">Hello World, Activity03!</string> 
 <string name="app_name">activity03</string> 
 <string name="resultLabel">result</string> 
 <string name="symbol">乘以</string> 
 <string name="calculate">计算</string> 
 <string name="exit">退出</string> 
 <string name="about">关于</string> 
</resources> 

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
  package="mars.activity03" 
  android:versionCode="1" 
  android:versionName="1.0"> 
 <application android:icon="@drawable/icon" android:label="@string/app_name"> 
  <activity android:name=".Activity03" 
     android:label="@string/app_name"> 
   <intent-filter> 
    <action android:name="android.intent.action.MAIN" /> 
    <category android:name="android.intent.category.LAUNCHER" /> 
   </intent-filter> 
  </activity> 
  <activity android:name=".ResultActivity" android:label="@string/resultLabel"/><!--这里使ResultActivity标题栏显示result--> 
 </application> 
 <uses-sdk android:minSdkVersion="4" /> 
 
</manifest>