Question

我想和TabHost一起使用。但它无法成功添加标签。当它即将来临tabHost.addTab(tab1);时它就会崩溃。含NullPointerException

XML

 <TabHost
        android:id="@+id/tabHost"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="0dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_weight="0.2">

        <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="fill_parent"></FrameLayout>
        </LinearLayout>
    </TabHost>

JAVA

package abc.trempital.Activities;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.TabHost;
import android.content.Intent;
import android.widget.TabHost.TabSpec;
import abc.trempital.R;

public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TabHost tabHost = (TabHost) findViewById(R.id.tabHost);

        TabSpec tab1 = tabHost.newTabSpec("First Tab");
        TabSpec tab2 = tabHost.newTabSpec("Second Tab");


        tab1.setIndicator("first");
        tab1.setContent(new Intent(this, SuggestsTabActivity.class));

        tab2.setIndicator("second");
        tab2.setContent(new Intent(this, WantedsTabActivity.class));


        tabHost.addTab(tab1);
        tabHost.addTab(tab2);
    }
}

ERROR

06-02 13:00:22.657 15890-15890/? E/AndroidRuntime: FATAL EXCEPTION: main
                                               Process: abc.button, PID: 15890
                                               java.lang.RuntimeException: Unable to start activity ComponentInfo{abc.button/abc.trempital.Activities.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TabWidget.addView(android.view.View)' on a null object reference
                                                   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
                                                   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                   at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                   at android.os.Handler.dispatchMessage(Handler.java:102)
                                                   at android.os.Looper.loop(Looper.java:148)
                                                   at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TabWidget.addView(android.view.View)' on a null object reference
                                                   at android.widget.TabHost.addTab(TabHost.java:218)
                                                   at abc.trempital.Activities.MainActivity.onCreate(MainActivity.java:30)
                                                   at android.app.Activity.performCreate(Activity.java:6237)
                                                   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
                                                   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
                                                   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
                                                   at android.app.ActivityThread.-wrap11(ActivityThread.java) 
                                                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
                                                   at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                   at android.os.Looper.loop(Looper.java:148) 
                                                   at android.app.ActivityThread.main(ActivityThread.java:5417) 
                                                   at java.lang.reflect.Method.invoke(Native Method) 
                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Answer 1

从andorid的官方网站试用this example。

Answer 2

TabHost很旧，请使用TabLayout代替https://developer.android.com/reference/android/support/design/widget/TabLayout.html

TabHost无法添加选项卡

2 个答案: