有人可以在TabHost的这个例子中帮助我吗？ 我遇到的问题是，当我试图运行应用程序时 我得到Null Pointer Exception。
以下是代码，如果有人需要查看。
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);
}
}
任何人以任何方式协助或指向我的方向将不胜感激。 问候 西拉
EDIT-- 这是我得到的错误的LogCat视图
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
由于 西拉
编辑2 - 这里是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>
这是TabbarExample清单
<?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
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
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， 请求Healp，我焦急地等待。 问候。 西拉
编辑3 ---
我已将这些以下行添加到我的清单文件
<activity android:name=".FirstTab"/>
<activity android:name=".SecondTab"/>
但我仍然得到同样的错误：（
这是我主要活动onCreate methid的行，我收到此错误
/**
* add the created tab to the tab host for display
**/
tabHost.addTab(spec1);
tabHost.addTab(spec2);
感谢 西拉
答案 0 :(得分：1)
首先，定义清单中两个标签的活动：
<?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 {
标签活动的类声明很好。
答案 1 :(得分：0)
mlam=new LocalActivityManager(this,true);
而不是
mlam=new LocalActivityManager(this,false);
mlam=new LocalActivityManager(this,true);
setContentView(R.layout.main_window);
TabHost tabHost = (TabHost) findViewById(android.R.id.tabhost);
mlam.dispatchCreate(savedInstanceState);
tabHost.setup(mlam );
TabSpec inboxSpec = tabHost.newTabSpec(INBOX_SPEC);
inboxSpec.setIndicator(INBOX_SPEC, getResources().getDrawable(R.drawable.icon_inbox));
Intent inboxIntent = new Intent(this, InboxActivity.class);
inboxSpec.setContent(inboxIntent);
TabSpec outboxSpec = tabHost.newTabSpec(OUTBOX_SPEC);
outboxSpec.setIndicator(OUTBOX_SPEC, getResources().getDrawable(R.drawable.icon_outbox));
Intent outboxIntent = new Intent(this, OutboxActivity.class);
outboxSpec.setContent(outboxIntent);
TabSpec profileSpec = tabHost.newTabSpec(PROFILE_SPEC);
profileSpec.setIndicator(PROFILE_SPEC, getResources().getDrawable(R.drawable.icon_profile));
Intent profileIntent = new Intent(this, ProfileActivity.class);
profileSpec.setContent(profileIntent);
tabHost.addTab(inboxSpec);
tabHost.addTab(outboxSpec);
tabHost.addTab(profileSpec);