理解Task

一.实验要求。

app1的activity1有两个按钮，一个按钮跳转到Activity2，

另外一个按钮跳转到打电话的页面，打电话这个功能不属于app1，我们假设它为app2。

 首先默认进入app1的activity1，点击button1后跳转到activity2，

再点击activity2的按钮后跳转到activity1，再点击button2跳转到打电话页面，

最后依次点返回按钮，大家看Task栈效果。

二.训练目标。

理解Task的含义。

三.代码

[java] view plain copy
package com.test3.task;  
  
import android.app.Activity;  
import android.content.Intent;  
import android.net.Uri;  
import android.os.Bundle;  
import android.view.Menu;  
import android.view.MenuItem;  
import android.view.View;  
  
public class FirstActivity extends Activity {  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_first);          
    }  
      
    public void toSecond(View view){  
        Intent intent = new Intent (this,SecondActivity.class);  
        startActivity(intent);  
    }  
      
    public void toCall(View view){  
        Intent intentPhone = new Intent(Intent.ACTION_DIAL);  
        intentPhone.setData(Uri.parse("tel:10086"));  
        startActivity(intentPhone);  
    }  
      
    public void toDial(View view){  
        Intent intentDail= new Intent(Intent.ACTION_DIAL);    
        intentDail.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);       
        startActivity(intentDail);   
    }  
  
    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        // Inflate the menu; this adds items to the action bar if it is present.  
        getMenuInflater().inflate(R.menu.first, menu);  
        return true;  
    }  
  
    @Override  
    public boolean onOptionsItemSelected(MenuItem item) {  
        // Handle action bar item clicks here. The action bar will  
        // automatically handle clicks on the Home/Up button, so long  
        // as you specify a parent activity in AndroidManifest.xml.  
        int id = item.getItemId();  
        if (id == R.id.action_settings) {  
            return true;  
        }  
        return super.onOptionsItemSelected(item);  
    }  
}  
SecondActivity:
[java] view plain copy
package com.test3.task;  
  
import android.app.Activity;  
import android.content.Intent;  
import android.os.Bundle;  
import android.view.Menu;  
import android.view.MenuItem;  
import android.view.View;  
  
public class SecondActivity extends Activity {  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_second);  
    }  
  
    public void toFirst(View view){  
        Intent intent = new Intent (this,FirstActivity.class);  
        startActivity(intent);  
    }     
      
    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        // Inflate the menu; this adds items to the action bar if it is present.  
        getMenuInflater().inflate(R.menu.second, menu);  
        return true;  
    }  
  
    @Override  
    public boolean onOptionsItemSelected(MenuItem item) {  
        // Handle action bar item clicks here. The action bar will  
        // automatically handle clicks on the Home/Up button, so long  
        // as you specify a parent activity in AndroidManifest.xml.  
        int id = item.getItemId();  
        if (id == R.id.action_settings) {  
            return true;  
        }  
        return super.onOptionsItemSelected(item);  
    }  
}  
activity_first.xml:
[html] view plain copy
<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"  
    tools:context="com.test3.task.FirstActivity" >  
  
    <Button  
        android:id="@+id/btntoSecond"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_alignParentTop="true"  
        android:layout_centerHorizontal="true"  
        android:layout_marginTop="118dp"  
        android:onClick="toSecond"  
        android:text="@string/to_Second" />  
  
    <Button  
        android:id="@+id/btntoCall"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_centerHorizontal="true"  
        android:layout_centerVertical="true"  
        android:onClick="toCall"  
        android:text="@string/to_call" />  
  
    <Button  
        android:id="@+id/btntoDial"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_below="@+id/btntoCall"  
        android:layout_centerHorizontal="true"  
        android:layout_marginTop="32dp"  
        android:onClick="toDial"  
        android:text="@string/to_dial" />  
  
</RelativeLayout>  
activity_second.xml:
[html] view plain copy
<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"  
    tools:context="com.test3.task.SecondActivity" >  
  
    <Button  
        android:id="@+id/btntoFirst"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_centerHorizontal="true"  
        android:layout_centerVertical="true"  
        android:onClick="toFirst"  
        android:text="@string/to_First" />  
  
</RelativeLayout>  

四.运行图