從今天開始，本專欄持續(xù)更新Android簡易實(shí)戰(zhàn)類博客文章。和以往專欄不同，此專欄只有實(shí)例。每個實(shí)例盡量按照知識點(diǎn)對應(yīng)相應(yīng)一章節(jié)的內(nèi)容去寫，循序漸進(jìn)。有些實(shí)例可能會與另一個專欄有重復(fù)的文章。

開始本專欄的第一個簡易案例：

首先設(shè)置兩個布局文件，一個布局文件進(jìn)行輸入數(shù)據(jù)，獲取加法運(yùn)算；另一個布局文件進(jìn)行顯示最終結(jié)果。Activity1啟動Activity2，并傳遞計算結(jié)果值給Activity2.

main.xml:

<?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>

頁面展示：

result.xml

activity03活動：

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當(dāng)中，要聲明四個控件 
//2.要為其中的兩個控件設(shè)置顯示的值 
//3.創(chuàng)建一個監(jiān)聽器類，監(jiān)聽按鈕按下的動作 
//4.將監(jiān)聽器類的對象，綁定在按鈕對象上 
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); 
 //根據(jù)控件的ID來取得代表控件的對象 
 factorOne = (EditText)findViewById(R.id.factorOne); 
 factorTwo = (EditText)findViewById(R.id.factorTwo); 
 symbol = (TextView)findViewById(R.id.symbol); 
 calculate = (Button)findViewById(R.id.calculate); 
 //為symbol和calculate設(shè)置顯示的值 
// symbol.setText("乘以"); 
// calculate.setText("計算"); 
 symbol.setText(R.string.symbol);//這里通過引用的方式，去String文件中引用。保證了業(yè)務(wù)邏輯、視圖、引用資源分開 
 calculate.setText(R.string.calculate); 
 //將監(jiān)聽器的對象綁定到按鈕對象上面 
 calculate.setOnClickListener(new CalculateListener()); 
 } 
 //當(dāng)客戶點(diǎn)擊MENU按鈕的時候，調(diào)用該方法 
 @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); 
 } 
 //當(dāng)客戶點(diǎn)擊菜單當(dāng)中的某一個選項(xiàng)時，會調(diào)用該方法 
 @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) { 
  //取得兩個EditText控件的值 
  String factorOneStr = factorOne.getText().toString(); 
  String factorTwoStr = factorTwo.getText().toString(); 
  //將這兩個值存放到Intent對象當(dāng)中 
  Intent intent = new Intent(); 
  intent.putExtra("one",factorOneStr); 
  intent.putExtra("two",factorTwoStr); 
  intent.setClass(Activity03.this, ResultActivity.class); 
  //使用這個Intent對象來啟動ResultActivity 
  Activity03.this.startActivity(intent); 
 } 
 } 
}

resultActivity:

package mars.activity03; 
 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.widget.TextView; 
//1.接受從Activity03當(dāng)中所傳遞的值 
//2.計算兩個值的積 
//3.將計算的結(jié)果顯示在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對象當(dāng)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); 
 //計算兩個值的積 
 int result = factorOneInt * factorTwoInt; 
 resultView.setText(result + ""); 
 } 
 
}

String.xml:

<?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">計算</string> 
 <string name="exit">退出</string> 
 <string name="about">關(guān)于</string> 
</resources>

最后再看一下配置文件：活動都要進(jìn)行注冊，并且設(shè)置Activity03為主活動

<?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"/><!--這里使ResultActivity標(biāo)題欄顯示result--> 
 </application> 
 <uses-sdk android:minSdkVersion="4" /> 
 
</manifest>

結(jié)果：