Tabhost空指针异常 [英] Tabhost Null Pointer Exception
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问题描述
能否有人请帮助我TabHost的这个例子吗？
我的问题是，当我试图运行应用程序
我得到空指针异常。
Can some one please assist me in this example of TabHost? The problem i have is, When I am trying to run the application I am getting Null Pointer Exception.
下面是code。如果有人需要去看看。
Here is the code if some one need to have a look.
public class TabBarExample extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/**
* TabHost will have Tabs
**/
TabHost tabHost = (TabHost)findViewById(android.R.id.tabhost);
/** TabSpec used to create a new tab.
* By using TabSpec only we can able to setContent to the tab.
* By using TabSpec setIndicator() we can set name to tab.
**/
TabHost.TabSpec spec1, spec2;
spec1 = tabHost.newTabSpec("tab_id_1").setIndicator("Tab One").setContent(new Intent().setClass(this, FirstTab.class));
spec2 = tabHost.newTabSpec("tab_id_2").setIndicator("Tab Two").setContent(new Intent().setClass(this, SecondTab.class));
/**
* create intent of each tab pressed
**/
//Intent intent1 = new Intent().setClass(this, FirstTab.class);
//Intent intent2 = new Intent().setClass(this, SecondTab.class);
/**
* add the created tab to the tab host for display
**/
// I am getting error at the following line
tabHost.addTab(spec1);
tabHost.addTab(spec2);
}
}
中的任何一个，以协助以任何方式或指向我一个方向将是AP preciated。
问候
设拉子
Any one to assist in any way or point me to a direction will be appreciated. Regards Shiraz
EDIT--
这里是我得到的错误的LogCat中查看
EDIT-- here is the LogCat view of the error i am getting
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): FATAL EXCEPTION: main
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.moonlight.tabbarexample/com.moonlight.tabbarexample.TabBarExample}: java.lang.NullPointerException
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1816)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1837)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.app.ActivityThread.access$1500(ActivityThread.java:132)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1033)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.os.Handler.dispatchMessage(Handler.java:99)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.os.Looper.loop(Looper.java:143)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.app.ActivityThread.main(ActivityThread.java:4196)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at java.lang.reflect.Method.invokeNative(Native Method)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at java.lang.reflect.Method.invoke(Method.java:507)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at dalvik.system.NativeStart.main(Native Method)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): Caused by: java.lang.NullPointerException
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.widget.TabHost$ViewIdContentStrategy.<init>(TabHost.java:591)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.widget.TabHost$ViewIdContentStrategy.<init>(TabHost.java:586)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.widget.TabHost$TabSpec.setContent(TabHost.java:441)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at com.moonlight.tabbarexample.TabBarExample.onCreate(TabBarExample.java:26)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1780)
06-18 23:18:30.547: ERROR/AndroidRuntime(1404): ... 11 more
06-18 23:20:06.984: ERROR/SettingsAppWidhetProvider(14282): level1 = 100.0
谢谢
设拉子
Thanks Shiraz
编辑2 -
这里的main.xml
EDIT 2 -- HERE IS main.xml
<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="5dip">
<TabWidget
android:id="@android:id/tabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="5dip" />
</LinearLayout>
</TabHost>
下面是TabbarExample清单
Here is TabbarExample manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.moonlight.tabbarexample"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="7" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".TabBarExample"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
这是Firsttab.java
And here is Firsttab.java
package com.moonlight.tabbarexample;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class FirstTab extends Activity{
public void onCreate ( Bundle savedInstanceState){
super.onCreate(savedInstanceState);
/* First Tab Content */
TextView textView = new TextView(this);
textView.setText("First Tab");
setContentView(textView);
}
}
最后一个SeconTab.java
last one SeconTab.java
package com.moonlight.tabbarexample;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class SecondTab extends Activity{
public void onCreate ( Bundle savedInstanceState){
super.onCreate(savedInstanceState);
/* First Tab Content */
TextView textView = new TextView(this);
textView.setText("Second Tab");
setContentView(textView);
}
}
谢谢你们，
pleaes healp，我焦急地等待着。
问候。
设拉子
Thanks guys, pleaes healp, i am anxiously waiting. Regards. Shiraz
编辑3 ---
我已经添加了这些下面一行到我的清单文件
I have added these following line to my manifest file
<activity android:name=".FirstTab"/>
<activity android:name=".SecondTab"/>
但我仍然得到同样的错误：（
but I am still getting the same error :(
这是我的主要活动线路的onCreate methid我在哪里得到这个错误
this is the line in my main activity onCreate methid where i am getting this error
/**
* add the created tab to the tab host for display
**/
tabHost.addTab(spec1);
tabHost.addTab(spec2);
谢谢
设拉子
thanks shiraz
推荐答案
首先，定义为您的清单中的两个选项卡活动：
First, define the activities for the two tabs in your manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.moonlight.tabbarexample"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="7" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".FirstTab" />
<activity android:name=".SecondTab" />
<activity android:name=".TabBarExample"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
最后，改变
public class TabBarExample extends Activity {
到
public class TabBarExample extends TabActivity {
您的标签活动类的声明就好了。
The class declarations for your tab activities are just fine.
这篇关于Tabhost空指针异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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