Android空指针异常问题，新手求教

Question

异常android

Answer 1

这是item.xml文件
<?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:orientation="horizontal" >    <TextView 
        android:layout_width="150px"
        android:layout_height="50px"
        android:gravity="center"
        android:id="@+id/name"/>    <TextView 
        android:layout_width="150px"
        android:layout_height="50px"
         android:gravity="center"
        android:id="@+id/age"/>
    
    <TextView 
        android:layout_width="fill_parent"
        android:layout_height="50px"
         android:gravity="center"
        android:id="@+id/money"/>
    
</LinearLayout>

Answer 2

这是main.xml文件
<?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:orientation="vertical" >    <ListView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="@+id/listView" /></LinearLayout>

Answer 3

出错异常
06-02 01:02:05.599: E/AndroidRuntime(17060): FATAL EXCEPTION: main
06-02 01:02:05.599: E/AndroidRuntime(17060): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.stu.sqlite/com.stu.sqlite.MainActivity}: java.lang.NullPointerException
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.os.Handler.dispatchMessage(Handler.java:99)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.os.Looper.loop(Looper.java:123)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.app.ActivityThread.main(ActivityThread.java:4627)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at java.lang.reflect.Method.invokeNative(Native Method)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at java.lang.reflect.Method.invoke(Method.java:521)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at dalvik.system.NativeStart.main(Native Method)
06-02 01:02:05.599: E/AndroidRuntime(17060): Caused by: java.lang.NullPointerException
06-02 01:02:05.599: E/AndroidRuntime(17060):  at com.stu.sqlite.MainActivity.show(MainActivity.java:49)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at com.stu.sqlite.MainActivity.onCreate(MainActivity.java:27)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
06-02 01:02:05.599: E/AndroidRuntime(17060):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
06-02 01:02:05.599: E/AndroidRuntime(17060):  ... 11 more

Answer 4

main.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:orientation="vertical" >
 
    <ListView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/listView" />
 
</LinearLayout>

Answer 5

android:text="@+id/listView"
这里应该是
android:id="@+id/listView"