Android 《第一行代码》 第二章练习代码 ActivityTest

FirstActivity.java

 package com.example.activitytest;

 import android.app.Activity;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.Window;
 import android.widget.Button;
 import android.widget.Toast;

 public class FirstActivity extends Activity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

         /*
          * 隐藏标题栏，定要在setContentView()之前执行 ，否则会报错 java.lang.RuntimeException:
          * Unable to start activity ComponentInfo:
          * android.util.AndroidRuntimeException: requestFeature() must be called
          * before adding content
          */
         requestWindowFeature(Window.FEATURE_NO_TITLE);

         // 加载布局
         setContentView(R.layout.first_layout);

         Button button1 = (Button) findViewById(R.id.button_1);
         button1.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View v) {
                 // toast提示
                 // Toast.makeText(FirstActivity.this, "You click Button 1",
                 // Toast.LENGTH_SHORT).show();

                 // 销毁活动
                 // finish();

                 // Intent实现活动跳转，显示Intent
                 // Intent intent = new Intent(FirstActivity.this,
                 // SecondActivity.class);
                 // startActivity(intent);

                 // 隐式Intent
                 // Intent intent = new
                 // Intent("com.example.activitytest.ACTION_START");
                 // intent.addCategory("com.example.activitytest.MY_CATEGORY");
                 // startActivity(intent);

                 // 启动其他程序的活动
                 // Intent intent = new Intent(Intent.ACTION_DIAL);
                 // // intent.setData(Uri.parse("http://www.baidu.com"));
                 // intent.setData(Uri.parse("tel:10086"));
                 // startActivity(intent);
                 //
                 // 用intent传递数据
                 // String data = "Hello SecondActiyity";
                 // Intent intent = new Intent(FirstActivity.this,
                 // SecondActivity.class);
                 // intent.putExtra("extra_data", data); //键，值
                 // startActivity(intent);

                 // 返回数据给上一个活动
                 Intent intent = new Intent(FirstActivity.this,
                         SecondActivity.class);
                 startActivityForResult(intent, 1);

             }

         });
     }

 /*    由于我们是使用startActivityForResult()方法来启动SecondActivity 的，在SecondActivity
     被销毁之后会回调上一个活动的onActivityResult()方法
     第一个参数requestCode，即我们在启动活动时传入的请求码。第二个参数resultCode，即我们在返回数据时传入的处理结果。
     第三个参数data，即携带着返回数据的Intent。*/
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         switch (requestCode) {
         case 1:
             if (resultCode == RESULT_OK) {
                 String returnedData = data.getStringExtra("data_return");
                 Log.d("FirstActivity", returnedData);
             }
             break;
         default:
         }
     }

     // 显示菜单
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         getMenuInflater().inflate(R.menu.main, menu);
         return true;
     }

     // 菜单相应事件
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
         case R.id.add_item:
             Toast.makeText(this, "You clicked add", Toast.LENGTH_SHORT).show();
             break;
         case R.id.remove_item:
             Toast.makeText(this, "You clicked remove", Toast.LENGTH_SHORT)
                     .show();
             break;
         default:
         }
         return true;
     }
 }

SecondActivity.java

 package com.example.activitytest;

 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.Window;
 import android.widget.Button;

 public class SecondActivity extends Activity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         requestWindowFeature(Window.FEATURE_NO_TITLE);
         setContentView(R.layout.second_layout);
         // 用intent传递数据
         // Intent intent = getIntent();
         // String data = intent.getStringExtra("extra_data");
         // Log.d("SecondActivity",data);

         // 返回数据给上一个活动
         Button button2 = (Button) findViewById(R.id.button_2);
         button2.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View v) {
                 Intent intent = new Intent();
                 intent.putExtra("data_return", "Hello FirstActivity");
                 setResult(RESULT_OK, intent);
                 finish();
             }
         });
     }

     // 通过按下Back 键回到FirstActivity
     @Override
     public void onBackPressed() {
         Intent intent = new Intent();
         intent.putExtra("data_return", "Hello FirstActivity");
         setResult(RESULT_OK, intent);
         finish();
     }

 }

first_layout.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical" >

 <!--@+id/id_name:在XML中定义一个id，
     @id/id_name:引用一个id
     wrap_content:示当前元素的高度只要能刚好包含里面的内容就行 -->
     <Button
         android:id="@+id/button_1"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="Button 1"
         />

 </LinearLayout>

/ActivityTest/res/menu/main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <menu xmlns:android="http://schemas.android.com/apk/res/android" >
     <item
         android:id="@+id/add_item"
         android:title="Add" />
     <item
         android:id="@+id/remove_item"
         android:title="Remove" />

 </menu>

/ActivityTest/AndroidManifest.xml

 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.activitytest"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="8"
         android:targetSdkVersion="19" />

     <application
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <!-- .FirstActivity :com.example.activitytest.FirstActivity 的缩写 -->
         <activity
             android:name=".FirstActivity"
             android:label="This is FirstActivity">
             <intent-filter>
                 <!--   点击桌面应用程序图标时首先打开的就是这个活动 -->
                 <action android:name="android.intent.action.MAIN"/>
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>

         <activity android:name=".SecondActivity">
             <intent-filter>
                 <!--<action>和<category>中的内容同时能够匹配上Intent中指定的action 和category时，
                 这个活动才能响应该Intent。-->
                 <action android:name="com.example.activitytest.ACTION_START" />
                 <category android:name="android.intent.category.DEFAULT" />
                 <category android:name="com.example.activitytest.MY_CATEGORY"/>
             </intent-filter>
         </activity>
         <!--可以相应打开网页的intent-->
         <activity android:name=".ThirdActivity" >
             <intent-filter>
                 <action android:name="android.intent.action.VIEW" />
                 <category android:name="android.intent.category.DEFAULT" />
                 <data android:scheme="http" />
             </intent-filter>
         </activity>
     </application>

 </manifest>