Android 2.3.3
我有一个TabLayout，我试图为TabHost中的3个Tab添加三个活动。这是代码。
<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/tabhost"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_marginBottom="62dp" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TabWidget
android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</TabWidget>
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
android:id="@+id/tab1"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</LinearLayout>
<LinearLayout
android:id="@+id/tab2"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</LinearLayout>
<LinearLayout
android:id="@+id/tab3"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</LinearLayout>
</FrameLayout>
</LinearLayout>
</TabHost>
类文件:::
public class Class_Home_Page extends Activity {
TabHost tbHost_Home_Page;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
tbHost_Home_Page = (TabHost) findViewById(R.id.tabhost);
TabSpec contacts = tbHost_Home_Page.newTabSpec("Contacts");
contacts.setIndicator("Contacts", getResources().getDrawable(R.drawable.contacts));
Intent contactsIntent = new Intent(this, Class_Contacts.class);
contacts.setContent(contactsIntent);
TabSpec add_contact = tbHost_Home_Page.newTabSpec("Add Contact");
contacts.setIndicator("Add Contact", getResources().getDrawable(R.drawable.addcontact));
Intent addContactIntent = new Intent(this, Class_Add_Contact.class);
contacts.setContent(addContactIntent);
TabSpec delete_contact = tbHost_Home_Page.newTabSpec("Delete Contact");
contacts.setIndicator("Delete Contact", getResources().getDrawable(R.drawable.deletecontact));
Intent deleteContactIntent = new Intent(this, Class_Delete_Contact.class);
contacts.setContent(deleteContactIntent);
tbHost_Home_Page.addTab(contacts); // Line with Exception
tbHost_Home_Page.addTab(add_contact);
tbHost_Home_Page.addTab(delete_contact);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_home_page, menu);
return true;
}
}
这是我得到:::的例外
03-24 21:27:13.030: E/AndroidRuntime(402): FATAL EXCEPTION: main
03-24 21:27:13.030: E/AndroidRuntime(402): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobilevoiceapps.speeddial/com.mobilevoiceapps.speeddial.Class_Home_Page}: java.lang.NullPointerException
03-24 21:27:13.030: E/AndroidRuntime(402): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.os.Handler.dispatchMessage(Handler.java:99)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.os.Looper.loop(Looper.java:123)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.app.ActivityThread.main(ActivityThread.java:3683)
03-24 21:27:13.030: E/AndroidRuntime(402): at java.lang.reflect.Method.invokeNative(Native Method)
03-24 21:27:13.030: E/AndroidRuntime(402): at java.lang.reflect.Method.invoke(Method.java:507)
03-24 21:27:13.030: E/AndroidRuntime(402): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-24 21:27:13.030: E/AndroidRuntime(402): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-24 21:27:13.030: E/AndroidRuntime(402): at dalvik.system.NativeStart.main(Native Method)
03-24 21:27:13.030: E/AndroidRuntime(402): Caused by: java.lang.NullPointerException
03-24 21:27:13.030: E/AndroidRuntime(402): at android.widget.TabHost.addTab(TabHost.java:212)
03-24 21:27:13.030: E/AndroidRuntime(402): at com.mobilevoiceapps.speeddial.Class_Home_Page.onCreate(Class_Home_Page.java:37)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-24 21:27:13.030: E/AndroidRuntime(402): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
03-24 21:27:13.030: E/AndroidRuntime(402): ... 11 more
可能是什么问题呢？
根据建议更改了代码。.仍然出现错误...
public class Class_Home_Page extends Activity {
TabHost tbHost_Home_Page;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
tbHost_Home_Page = (TabHost) findViewById(R.id.tabhost);
TabSpec contacts = tbHost_Home_Page.newTabSpec("Contacts");
contacts.setIndicator("Contacts", getResources().getDrawable(R.drawable.contacts));
Intent contactsIntent = new Intent(this, Class_Contacts.class);
contacts.setContent(contactsIntent);
TabSpec add_contact = tbHost_Home_Page.newTabSpec("Add Contact");
add_contact.setIndicator("Add Contact", getResources().getDrawable(R.drawable.addcontact));
Intent addContactIntent = new Intent(this, Class_Add_Contact.class);
add_contact.setContent(addContactIntent);
TabSpec delete_contact = tbHost_Home_Page.newTabSpec("Delete Contact");
delete_contact.setIndicator("Delete Contact", getResources().getDrawable(R.drawable.deletecontact));
Intent deleteContactIntent = new Intent(this, Class_Delete_Contact.class);
delete_contact.setContent(deleteContactIntent);
tbHost_Home_Page.addTab(contacts);
tbHost_Home_Page.addTab(add_contact);
tbHost_Home_Page.addTab(delete_contact);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_home_page, menu);
return true;
}
}
这是错误..在同一行
03-24 21:49:01.330: E/AndroidRuntime(499): FATAL EXCEPTION: main
03-24 21:49:01.330: E/AndroidRuntime(499): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobilevoiceapps.speeddial/com.mobilevoiceapps.speeddial.Class_Home_Page}: java.lang.NullPointerException
03-24 21:49:01.330: E/AndroidRuntime(499): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.os.Handler.dispatchMessage(Handler.java:99)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.os.Looper.loop(Looper.java:123)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.app.ActivityThread.main(ActivityThread.java:3683)
03-24 21:49:01.330: E/AndroidRuntime(499): at java.lang.reflect.Method.invokeNative(Native Method)
03-24 21:49:01.330: E/AndroidRuntime(499): at java.lang.reflect.Method.invoke(Method.java:507)
03-24 21:49:01.330: E/AndroidRuntime(499): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-24 21:49:01.330: E/AndroidRuntime(499): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-24 21:49:01.330: E/AndroidRuntime(499): at dalvik.system.NativeStart.main(Native Method)
03-24 21:49:01.330: E/AndroidRuntime(499): Caused by: java.lang.NullPointerException
03-24 21:49:01.330: E/AndroidRuntime(499): at android.widget.TabHost.addTab(TabHost.java:212)
03-24 21:49:01.330: E/AndroidRuntime(499): at com.mobilevoiceapps.speeddial.Class_Home_Page.onCreate(Class_Home_Page.java:37)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-24 21:49:01.330: E/AndroidRuntime(499): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
03-24 21:49:01.330: E/AndroidRuntime(499): ... 11 more
最佳答案
您忘记为setContent和setIndicator设置add_contact和delete_contact了。将您的代码更改为：
TabSpec add_contact = tbHost_Home_Page.newTabSpec("Add Contact");
// use add_contact instead of contacts
add_contact.setIndicator("Add Contact",
getResources().getDrawable(R.drawable.addcontact));
Intent addContactIntent = new Intent(this, Class_Contacts.class);
// use add_contact instead of contacts
add_contact.setContent(addContactIntent);
TabSpec delete_contact = tbHost_Home_Page.newTabSpec("Delete Contact");
// use delete_contact instead of contacts
delete_contact.setIndicator("Delete Contact",
getResources().getDrawable(R.drawable.deletecontact));
Intent deleteContactIntent = new Intent(this, Class_Contacts.class);
// use delete_contact instead of contacts
delete_contact.setContent(deleteContactIntent);