我有一个在运行时显示项目列表的应用程序。当用户按下 Button 时，所有选定的项目都应被删除(选择由 CheckBox 决定)。在纵向模式下一切正常，但是当我切换到横向模式时当行数超过 3 时，按下删除按钮会出现强制关闭异常 并且我无法打印堆栈跟踪。 当行数不超过 3 行时，它会完美运行! 我已经为 layout(纵向)和 layout-land 目录编写了布局。代码和布局如下:

这是删除按钮的处理程序:

   Button DeleteGoods=(Button)findViewById(R.id.DeleteSelectedGoodsButton);
   DeleteGoods.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            CheckBox cbx = (CheckBox)listView.findViewById(R.id.ChkOrder);
            int firstPosition = listView.getFirstVisiblePosition();
                for (int i = firstPosition; i < listView.getCount(); i++) {

                    View v1 = listView.getChildAt(i);

                    cbx = (CheckBox)v1.findViewById(R.id.ChkOrder);
                    if(cbx.isChecked())
                        checkedItemPosition=i;                  
                }
                try {

                    DeleteCheckedItem(checkedItemPosition);

                    Toast.makeText(getApplicationContext(),"The selected order has been deleted successfully.", Toast.LENGTH_SHORT).show();

                    finish();
                    startActivity(getIntent());
                } catch (Exception e) {

                    Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
                }


        }

    });

这是横向模式下的布局:

<?xml version="1.0" encoding="utf-8"?>

    <RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="#000000" >
        <Button 
            android:id="@+id/DeleteSelectedGoodsButton"
            android:layout_width="150dp"
            android:layout_height="45dp"
            android:text="@string/DeleteSelectedGoods"
            android:layout_alignParentTop="true"
            android:layout_alignParentLeft="true" />
        <Button 
            android:id="@+id/ConfirmDelete"
            android:layout_width="150dp"
            android:layout_height="45dp"
            android:text="@string/ConfirmDeleteButton"
            android:layout_alignParentTop="true"
            android:layout_centerHorizontal="true" />
        <Button 
            android:id="@+id/CancelButton"
            android:layout_width="150dp"
            android:layout_height="45dp"
            android:text="@string/CancelButton"
            android:layout_alignParentTop="true"
            android:layout_alignParentRight="true" />
        <TextView 
            android:id="@+id/aa"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:layout_below="@id/CancelButton" />

        <TextView 
            android:id="@+id/GOODNAME_CELL"
            android:layout_width="180dp"
            android:layout_height="wrap_content"
            android:background="@drawable/border"
            android:textSize="18dp"
            android:text="Order"
            android:paddingLeft="5dp"
            android:layout_below="@id/aa"
            android:layout_alignParentLeft="true" />
         <TextView 
            android:id="@+id/GOODUNITPRICE_CELL"
            android:layout_width="180dp"
            android:layout_height="wrap_content"
            android:background="@drawable/border"
            android:textSize="18dp"
            android:text="Unit Price"
            android:paddingLeft="5dp"
            android:layout_below="@id/aa"
            android:layout_toRightOf="@id/GOODNAME_CELL" />
         <TextView 
            android:id="@+id/QUANTITYCELL"
            android:layout_width="120dp"
            android:layout_height="wrap_content"
            android:background="@drawable/border"
            android:textSize="18dp"
            android:text="Quantity"
            android:paddingLeft="5dp"
            android:layout_below="@id/aa"
            android:layout_toRightOf="@id/GOODUNITPRICE_CELL" />
         <ListView 
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        style="@style/CodeFont"
        android:layout_alignParentLeft="true"
        android:layout_below="@id/GOODUNITPRICE_CELL" />

         <TextView
            android:id="@+id/TotalPriceTextview"
            android:layout_width="600dp"
            android:layout_height="wrap_content"
            android:text=""
            android:layout_alignParentBottom="true"
            android:layout_centerHorizontal="true"
            android:background="@drawable/back"
            android:textColor="#FFFFFF"
            android:textSize="20dp" />

    </RelativeLayout>

这是我遇到的异常:

02-19 10:07:11.398: E/AndroidRuntime(4335): FATAL EXCEPTION: main
02-19 10:07:11.398: E/AndroidRuntime(4335): java.lang.NullPointerException
02-19 10:07:11.398: E/AndroidRuntime(4335):     at com.example.nfc.PrepopSqliteDbActivity$1.onClick(PrepopSqliteDbActivity.java:117)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at android.view.View.performClick(View.java:2552)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at android.view.View$PerformClick.run(View.java:9229)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at android.os.Handler.handleCallback(Handler.java:587)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at android.os.Handler.dispatchMessage(Handler.java:92)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at android.os.Looper.loop(Looper.java:138)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at android.app.ActivityThread.main(ActivityThread.java:3701)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at java.lang.reflect.Method.invokeNative(Native Method)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at java.lang.reflect.Method.invoke(Method.java:507)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:878)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:636)
02-19 10:07:11.398: E/AndroidRuntime(4335):     at dalvik.system.NativeStart.main(Native Method)
02-19 10:07:11.408: W/ActivityManager(1768):   Force finishing activity com.example.nfc/.PrepopSqliteDbActivity
02-19 10:07:11.909: W/ActivityManager(1768): Activity pause timeout for HistoryRecord{40b2ed78 com.example.nfc/.PrepopSqliteDbActivity}
02-19 10:07:16.353: I/InputDispatcher(1768): Application is not responding: Window{40a73e60 com.example.nfc/com.example.nfc.PrepopSqliteDbActivity paused=false}.  5004.7ms since event, 5004.4ms since wait started
02-19 10:07:16.353: I/InputDispatcher(1768): Dropping event because the pointer is not down.
02-19 10:07:16.353: I/InputDispatcher(1768): Dropping event because the pointer is not down.
02-19 10:07:16.353: I/WindowManager(1768): Input event dispatching timed out sending to com.example.nfc/com.example.nfc.PrepopSqliteDbActivity
02-19 10:07:16.353: I/ActivityManager(1768): Crashing app skipping ANR: ProcessRecord{40a1b188 4335:com.example.nfc/10003} keyDispatchingTimedOut
02-19 10:07:21.428: W/ActivityManager(1768): Launch timeout has expired, giving up wake lock!
02-19 10:07:21.908: W/ActivityManager(1768): Activity idle timeout for HistoryRecord{40a1b7d8 com.example.nfc/.Buy}
02-19 10:07:26.963: I/touchd(1518): 'ab8500_usb' is online
02-19 10:07:26.963: I/touchd(1518): handling_uevent: event is 1

编辑

这是第 117 行:

DeleteCheckedItem(checkedItemPosition);

这是方法的主体:

private void DeleteCheckedItem(int chkPosition)
{   
    String strName=goods.get(chkPosition).get(GOOD_NAME);
    String strPrice=goods.get(chkPosition).get(GOOD_UNITPRICE);
    String strQuantity=goods.get(chkPosition).get(QUANTITY);
    String whereClause = "GOOD_NAME = ? AND GOOD_UNITPRICE= ? AND QUANTITY= ?";
    String[] whereArgs = {strName,strPrice,strQuantity};
    database.delete(TABLE_NAME, whereClause, whereArgs);
}

最佳答案

checkedItemPosition 是 int 还是 Integer？

我猜它是一个初始化为 null 的 Integer。

当你旋转时， Activity 被重新创建并且你的 checkedItemPosition 被重新初始化为 null。

然后您进入您的 for 循环，但是没有一个 Checkbox View 被选中，因此您的 checkedItemPosition 仍然是 null。

您尝试在 null 上调用 DeleteItemChecked，而它需要原始 int 并且瞧:NullPointerException。

解决方案:将checkedItemPosition初始化为0。

关于android - 在横向模式下强制关闭，但在纵向模式下不强制关闭，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14950418/