使用设备进行测试 - 每当我锁定屏幕(或在闲置1分钟后休眠)时,应用程序崩溃,并且 logcat
在 onResume()
方法中始终显示 NullPointerException
.
这是我获得异常的代码的一小部分:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.critical_items_list);
// instantiate member variables
mExtras = getIntent().getExtras();
mItems_P1 = mExtras.getParcelableArrayList(EXTRA_ITEMS_P1);
mItems_P2 = mExtras.getParcelableArrayList(EXTRA_ITEMS_P2);
mItems_Engine = mExtras.getParcelableArrayList(EXTRA_ITEMS_ENGINE);
}
protected void onResume() {
super.onResume();
ImageView imageAddToMultiple = (ImageView) findViewById(R.id.image_add_to_multiple);
//This is where the I get the NullPointer
imageAddToMultiple.setOnClickListener(listenerAddToMultipleItems);
refreshLists();
ListView listP1 = (ListView) findViewById(R.id.list_p1);
ListView listP2 = (ListView) findViewById(R.id.list_p2);
ListView listEngine = (ListView) findViewById(R.id.list_engine);
listP1.setAdapter(new MyAdapter(mList_P1));
listP2.setAdapter(new MyAdapter(mList_P2));
listEngine.setAdapter(new MyAdapter(mList_Engine));
}
imageView本身位于 RelativeLayout
:
<?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" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="@dimen/standard_bar_height"
android:background="@color/green"
android:baselineAligned="false" >
<LinearLayout
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<TextView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
android:text="@string/plant_1"
android:textColor="@android:color/black" />
</LinearLayout>
<LinearLayout
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<TextView
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:gravity="center"
android:text="@string/plant_2"
android:textColor="@android:color/black" />
</LinearLayout>
<RelativeLayout
android:id="@+id/RelativeLayout1"
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1" >
<ImageView
android:id="@+id/image_add_to_multiple"
android:layout_width="@dimen/standard_bar_height"
android:layout_height="@dimen/standard_bar_height"
android:layout_alignParentRight="true"
android:layout_centerHorizontal="true"
android:contentDescription="@string/description_add_to_multiple_items"
android:src="@android:drawable/ic_menu_add" />
<TextView
android:id="@+id/TextView1"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:gravity="center"
android:text="@string/engine"
android:textColor="@android:color/black" />
</RelativeLayout>
</LinearLayout>
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ListView
android:id="@+id/list_p1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" >
</ListView>
<View
android:layout_width="2dp"
android:layout_height="fill_parent"
android:background="@color/green" />
<ListView
android:id="@+id/list_p2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" >
</ListView>
<View
android:layout_width="2dp"
android:layout_height="fill_parent"
android:background="@color/green" />
<ListView
android:id="@+id/list_engine"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" >
</ListView>
</LinearLayout>
</LinearLayout>
我不知道为什么我得到这个 NullPointer
.
FATAL EXCEPTION:main java.lang.RuntimeException:无法在android上恢复活动{nmw.nss / nmw.nss.CriticalList}:android.app.ActivityThread.performResumeActivity(ActivityThread.java:2820)中的java.lang.NullPointerException . app.ActivityThread.handleResumeActivity(ActivityThread.java:2859)在Android.app.ActivityThread $ android.app.ActivityThread.access $ 600(ActivityThread.java:139)的android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2242) H.handleMessage(ActivityThread.java:1262)位于android.app.A.运行时,Android.A.T.Thread.main上的android.os.Handler.dispatchMessage(Handler.java:99)以及android.app.Looper.loop(Looper.java:154)(ActivityThread) .java:4974)at java.lang.reflect.Method.invokeNative(Native Method)at java.lang.reflect.Method.invoke(Method.java:511)at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run (ZygoteInit.java:784)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)at dalvik.system.NativeStart.main(Native Method)引起:java.lang.NullP在android.app.InstrumentationCallActivityRnume(Instrumentation.java:1236)的android.app.Activity.performResume(Activity.java:4620)上的nmw.nss.CriticalList.onResume(CriticalList.java:93)的ointerException .ActivityThread.performResumeActivity(ActivityThread.java:2804)... 12个其他
谢谢 .
编辑:我添加了完整的活动(排序), xml
和 logcat
. 我是否需要覆盖任何 Activity
方法,也许 onStop
或 onPause
才能使其工作?
2 回答
终于找到了!我的应用程序基本上是设计为在横向模式下运行,并且在清单中我添加了------- android:screenOrientation =“landscape” .
好吧,这就是问题:在你锁定设备的模式下,findViewById()总是在纵向模式下搜索XML并且在我的情况下,根本没有ImageView . 因此NullPointerException .
我假设您之前没有调用
setContentView()
,因此Imageview imageAddToMultiple
为null,当您尝试设置侦听器时,它会崩溃 .希望能帮助到你!