Question

我有一个应用程序，我可以在EditText元素中输入一个数字，当我按下“添加”按钮时，这个数字将被复制到ListView

当ListView与按钮和ListView

在同一个活动中时，我可以这样做

但是当我将ListView更改为另一个活动时，应用程序崩溃，这就是logcat：

return "error"

我该如何解决这个问题？

XML：

java.lang.RuntimeException: Unable to start activity ComponentInfo{shop.ned.shahbaa/shop.ned.shahbaa.Item1}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at shop.ned.shahbaa.Item1.onCreate(Item1.java:38)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)

班级：

<?xml version="1.0" encoding="utf-8"?>
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:scrollbarAlwaysDrawVerticalTrack="true"
    android:layout_height="fill_parent"
    android:layout_width="fill_parent">

    <TextView
        android:textSize="22sp"
        android:textColor="#992222"
        android:text="@string/label_add_new_product_quantity"
        android:textDirection="rtl"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:layout_row="0"
        android:layout_column="0" />

    <EditText
        android:id="@+id/editTextQuantityAddProduct"
        android:hint="@string/add_number"
        android:layout_width="fill_parent"
        android:inputType="number|phone"
        android:layout_row="1"
        android:layout_column="0" />

    <TextView
        android:textSize="22sp"
        android:id="@+id/unit_KG"
        android:textColor="#992222"
        android:text="@string/unit_KG"
        android:textDirection="rtl"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:layout_row="2"
        android:layout_column="0" />


    <View
        android:layout_width="match_parent"
        android:layout_height="1.5sp"
        android:background="#ffCDCC"
        android:layout_row="3"
        android:layout_column="0" />

    <TextView
        android:textSize="22sp"
        android:layout_width="fill_parent"
        android:textColor="#992222"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="@string/label"
        android:layout_row="4"
        android:layout_column="0" />


    <TextView
        android:textSize="22sp"
        android:id="@+id/label_Item2"
        android:layout_width="fill_parent"
        android:textColor="#992222"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="@string/label_Item2"
        android:layout_row="5"
        android:layout_column="0" />

    <View
        android:layout_width="match_parent"
        android:layout_height="1.5sp"
        android:background="#ffCDCC"
        android:layout_row="6"
        android:layout_column="0" />

    <Button
        android:id="@+id/buttonConfirmAddProduct"
        android:layout_column="0"
        android:background="#D00000"
        android:textSize="22sp"
        android:textColor="#FFF"
        android:text="@string/button_confirm_adding"
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:layout_row="7"
        android:layout_marginTop="10sp"/>

    <ListView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/listView"
        android:layout_row="8"
        android:layout_column="0" />

</GridLayout>

像这样工作但我在另一个带有id（shoppingList）的活动中有另一个listview，当我将“cart”id更改为它时，应用程序崩溃了。

以两种布局动态自动增长ListView

0 个答案: