Android tabHost NullPointer

Question

我是 android 编程的新手，但不是 Java。

我在以下位置收到有关 NPE 的错误消息:

12-09 10:29:58.247: D/dalvikvm(471): GC freed 711 objects / 54912 bytes in 163ms
12-09 10:29:58.337: D/dalvikvm(471): GC freed 45 objects / 1720 bytes in 37ms
12-09 10:29:58.457: D/AndroidRuntime(471): Shutting down VM
12-09 10:29:58.457: W/dalvikvm(471): threadid=3: thread exiting with uncaught exception (group=0x4001b188)
12-09 10:29:58.457: E/AndroidRuntime(471): Uncaught handler: thread main exiting due to uncaught exception
12-09 10:29:58.457: E/AndroidRuntime(471): java.lang.NullPointerException
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.widget.TabHost.dispatchWindowFocusChanged(TabHost.java:295)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1819)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.os.Looper.loop(Looper.java:123)
12-09 10:29:58.457: E/AndroidRuntime(471):  at android.app.ActivityThread.main(ActivityThread.java:4363)
12-09 10:29:58.457: E/AndroidRuntime(471):  at java.lang.reflect.Method.invokeNative(Native Method)
12-09 10:29:58.457: E/AndroidRuntime(471):  at java.lang.reflect.Method.invoke(Method.java:521)
12-09 10:29:58.457: E/AndroidRuntime(471):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
12-09 10:29:58.457: E/AndroidRuntime(471):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
12-09 10:29:58.457: E/AndroidRuntime(471):  at dalvik.system.NativeStart.main(Native Method)
12-09 10:29:58.467: I/dalvikvm(471): threadid=7: reacting to signal 3
12-09 10:29:58.467: E/dalvikvm(471): Unable to open stack trace file '/data/anr/traces.txt': Permission denied

这让我发疯。我在网上搜索了一个解决方案，虽然我多次看到错误被引用，但他们要么没有发布解决方案，要么这些解决方案对我不起作用。

这是我的文件。我很感激你能给我的任何帮助。

WorkbenchTicketDetailsActivity.java

package com.android.fm.workbench;
import com.android.fm.workbench.R;
import android.os.Bundle;
import android.widget.TabHost;
import android.widget.TabHost.TabSpec;
public class WorkbenchTicketDetailsActivity extends WorkbenchActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.ticketdetails);
    TabHost host = (TabHost)findViewById(R.id.tabhost);
    host.setup();
    TabSpec ticketdetailTab = host.newTabSpec("ticketdetails");
    ticketdetailTab.setIndicator(getResources().getString(R.string.tablabel_ticketdetails),getResources().getDrawable(android.R.drawable.ic_menu_manage));
    ticketdetailTab.setContent(R.id.TableLayout_TicketDetails);

    host.setCurrentTabByTag("ticketdetails");


    }
}

ticketdetails.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@drawable/fm_background"
        android:orientation="vertical" >
       <TabHost 
       xmlns:android="http://schemas.android.com/apk/res/android"  
        android:id="@+id/tabhost"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent">
       <LinearLayout 
          android:id="@+id/LinearLayout1"
          android:orientation="vertical"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent">
          <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">
              <ScrollView 
                  android:id="@+id/ScrollViewTicketDetails"
                  android:layout_width="fill_parent"
                  android:layout_height="fill_parent"
                  android:scrollbars="vertical">
                  <TableLayout
                      android:id="@+id/TableLayout_TicketDetails"
                      android:layout_width="fill_parent"
                      android:layout_height="fill_parent"
                      android:stretchColumns="*">
                      <TableRow
                          android:layout_width="fill_parent"
                          android:layout_height="wrap_content"
                          >
                          <TextView 
                          android:layout_width="fill_parent"
                          android:layout_height="wrap_content"
        android:text="test"
                              />
                      </TableRow>
                  </TableLayout>
              </ScrollView>
          </FrameLayout>              
      </LinearLayout>
   </TabHost>
</LinearLayout>

list .xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.android.fm.workbench"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="7" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".WorkbenchActivity" >
        </activity>
        <activity android:name="WorkbenchTicketDetailsActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/><category     android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>
        <activity android:name="WorkbenchLoginActivity"></activity>
        <activity android:name="WorkbenchSplashActivity">
        </activity>
    </application>

</manifest>

如果有一个我只是没有看到的简单解决方案，我深表歉意。很长一段时间以来，我一直在用头撞 table ，而且我知道这里有很多 super 明星，他们可以快速发现问题。

我尝试在 TabView 上从 Android 站点添加以下代码，并将现有的 ticketdetail.xml 代码替换为:

<?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="5dp">        
            <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="5dp" />    
        </LinearLayout>
</TabHost>

仍然给我一个空指针异常!!!

Answer 1

为什么不将 tabspec 添加到主机中？

host.addTab(spec);