提供java.lang.NullPointerException的自定义android布局
我对android编程比较陌生,在检测代码中出现以下错误的原因时遇到了一些困难: 10-18 18:15:45.083 31605-31605/?W/System.err?位于com.app.name.widgets.SizeNotifierRelativeLayout.onLayout(SizeNotifierRelativeLayout.java:43) 10-18 18:15:45.092 31605-31605/? E/AndroidRuntime?致命异常:主 java.lang.NullPointerException 我使用的是一个自定义布局提供java.lang.NullPointerException的自定义android布局,java,android,android-layout,nullpointerexception,android-statusbar,Java,Android,Android Layout,Nullpointerexception,Android Statusbar,我对android编程比较陌生,在检测代码中出现以下错误的原因时遇到了一些困难: 10-18 18:15:45.083 31605-31605/?W/System.err?位于com.app.name.widgets.SizeNotifierRelativeLayout.onLayout(SizeNotifierRelativeLayout.java:43) 10-18 18:15:45.092 31605-31605/? E/AndroidRuntime?致命异常:主 java.lang.N
com.app.name.widgets.SizeNotifierRelativeLayout
,由我的xml文件调用。错误发生在第43行,该行包含代码super.onLayout(已更改,l、t、r、b)代码>在下面的函数中:
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (delegate != null) {
View rootView = this.getRootView();
int usableViewHeight = rootView.getHeight() - AndroidUtilities.statusBarHeight - AndroidUtilities.getViewInset(rootView);
this.getWindowVisibleDisplayFrame(rect);
int keyboardHeight = usableViewHeight - (rect.bottom - rect.top);
delegate.onSizeChanged(keyboardHeight);
}
}
}
从我的研究中,我发现一个NullPointerException错误是由于声明了一个变量而没有创建一个对象;但由于我是java新手,所以要确定错误发生的位置对我来说有点困难。请给我指出正确的方向,我会非常感激的。下面是我的活动、布局和SizeNotifierRelativeLayout文件以及logcat。提前谢谢
Activity.java
package com.app.name;
import com.app.name.widgets.SizeNotifierRelativeLayout;
public class Activity extends ActionBarActivity implements ISideNavigationCallback, SizeNotifierRelativeLayout.SizeNotifierRelativeLayoutDelegate, NotificationCenter.NotificationCenterDelegate {
private SizeNotifierRelativeLayout sizeNotifierRelativeLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view);
AndroidUtilities.statusBarHeight = getStatusBarHeight();
sizeNotifierRelativeLayout = (SizeNotifierRelativeLayout) findViewById(R.id.chat_layout);
sizeNotifierRelativeLayout.delegate = this;
NotificationCenter.getInstance().addObserver(this, NotificationCenter.emojiDidLoaded);
}
/**
* Get the system status bar height
* @return
*/
public int getStatusBarHeight() {
int result = 0;
int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");
if (resourceId > 0) {
result = getResources().getDimensionPixelSize(resourceId);
}
return result;
}
}
package com.app.name.widgets;
import android.content.Context;
import android.graphics.Rect;
import android.view.View;
import android.widget.RelativeLayout;
import com.app.name.AndroidUtilities;
public class SizeNotifierRelativeLayout extends RelativeLayout {
private Rect rect = new Rect();
public SizeNotifierRelativeLayoutDelegate delegate;
public abstract interface SizeNotifierRelativeLayoutDelegate {
public abstract void onSizeChanged(int keyboardHeight);
}
public SizeNotifierRelativeLayout(Context context) {
super(context);
}
public SizeNotifierRelativeLayout(Context context, android.util.AttributeSet attrs) {
super(context, attrs);
}
public SizeNotifierRelativeLayout(Context context, android.util.AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
/**
* Calculate the soft keyboard height and report back to listener
* @param changed
* @param l
* @param t
* @param r
* @param b
*/
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (delegate != null) {
View rootView = this.getRootView();
int usableViewHeight = rootView.getHeight() - AndroidUtilities.statusBarHeight - AndroidUtilities.getViewInset(rootView);
this.getWindowVisibleDisplayFrame(rect);
int keyboardHeight = usableViewHeight - (rect.bottom - rect.top);
delegate.onSizeChanged(keyboardHeight);
}
}
}
activity\u view.xml
<com.app.name.widgets.SizeNotifierRelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/chat_layout"
android:background="@drawable/background"
tools:context="com.app.name.Activity">
<ListView
android:id="@+id/chat_list_view"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:divider="@drawable/chat_divider"
android:layout_width="match_parent"
android:scrollbarStyle="outsideOverlay"
android:layout_above="@+id/bottomlayout"
android:layout_height="match_parent"></ListView>
<LinearLayout
android:id="@+id/bottomlayout"
android:background="@android:color/white"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_alignParentBottom="true"
android:layout_height="wrap_content">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView android:src="@drawable/ic_msg_panel_smiles" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" android:layout_marginLeft="8dp" android:layout_marginRight="8dp"
android:layout_width="wrap_content" android:id="@+id/emojiButton" android:layout_alignBottom="@+id/chat_edit_text1" android:layout_marginBottom="8dp"
android:layout_height="wrap_content" />
<EditText
android:layout_marginTop="8dp"
android:layout_marginBottom="8dp"
android:id="@+id/chat_edit_text1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollHorizontally="false"
android:layout_toLeftOf="@+id/enter_chat1"
android:layout_toRightOf="@id/emojiButton"
android:layout_toEndOf="@id/emojiButton"
android:layout_toStartOf="@+id/enter_chat1"
android:hint="@string/type_your_message"
android:maxLines="4"
android:singleLine="false"
android:inputType="textCapSentences"
android:textSize="18sp"
android:paddingLeft="4dp" />
<ImageView android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:id="@+id/enter_chat1"
android:layout_width="wrap_content"
android:layout_marginBottom="8dp"
android:layout_height="wrap_content"
android:layout_alignBottom="@id/chat_edit_text1"
android:paddingLeft="13dp"
android:paddingStart="13dp"
android:paddingRight="17dp"
android:paddingEnd="17dp"
android:src="@drawable/ic_chat_send" />
</RelativeLayout>
</LinearLayout>
</com.app.name.widgets.SizeNotifierRelativeLayout>
logcat
10-18 18:51:12.154 712-712/?W/System.err?位于com.app.name.widgets.SizeNotifierRelativeLayout.onLayout(SizeNotifierRelativeLayout.java:43)
10-18 18:51:12.164 712-712/? E/AndroidRuntime?致命异常:主
java.lang.NullPointerException
在android.widget.AbsListView.obtainView(AbsListView.java:2247)
位于android.widget.ListView.makeAndAddView(ListView.java:1849)
在android.widget.ListView.fillDown(ListView.java:678)中
位于android.widget.ListView.fillFromTop(ListView.java:739)
位于android.widget.ListView.layoutChildren(ListView.java:1664)
在android.widget.AbsListView.onLayout(AbsListView.java:2050)
位于android.view.view.layout(view.java:14243)
位于android.view.ViewGroup.layout(ViewGroup.java:4490)
在android.widget.RelativeLayout.onLayout(RelativeLayout.java:1021)上
位于com.app.name.widgets.SizeNotifierRelativeLayout.onLayout(SizeNotifierRelativeLayout.java:43)
位于android.view.view.layout(view.java:14243)
位于android.view.ViewGroup.layout(ViewGroup.java:4490)
位于android.widget.FrameLayout.onLayout(FrameLayout.java:448)
位于android.view.view.layout(view.java:14243)
位于android.view.ViewGroup.layout(ViewGroup.java:4490)
位于android.widget.LinearLayout.setChildFrame(LinearLayout.java:1670)
位于android.widget.LinearLayout.layoutVertical(LinearLayout.java:1528)
位于android.widget.LinearLayout.onLayout(LinearLayout.java:1441)
位于android.view.view.layout(view.java:14243)
位于android.view.ViewGroup.layout(ViewGroup.java:4490)
位于android.widget.FrameLayout.onLayout(FrameLayout.java:448)
位于android.view.view.layout(view.java:14243)
位于android.view.ViewGroup.layout(ViewGroup.java:4490)
位于android.widget.LinearLayout.setChildFrame(LinearLayout.java:1670)
位于android.widget.LinearLayout.layoutVertical(LinearLayout.java:1528)
位于android.widget.LinearLayout.onLayout(LinearLayout.java:1441)
位于android.view.view.layout(view.java:14243)
位于android.view.ViewGroup.layout(ViewGroup.java:4490)
位于android.widget.FrameLayout.onLayout(FrameLayout.java:448)
位于android.view.view.layout(view.java:14243)
位于android.view.ViewGroup.layout(ViewGroup.java:4490)
在android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2230)
在android.view.ViewRootImpl.performTraversals上(ViewRootImpl.java:1994)
位于android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1181)
在android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4942)
在android.view.Choreographer$CallbackRecord.run(Choreographer.java:776)
位于android.view.Choreographer.doCallbacks(Choreographer.java:579)
位于android.view.Choreographer.doFrame(Choreographer.java:548)
在android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762)上
位于android.os.Handler.handleCallback(Handler.java:800)
位于android.os.Handler.dispatchMessage(Handler.java:100)
位于android.os.Looper.loop(Looper.java:194)
位于android.app.ActivityThread.main(ActivityThread.java:5370)
位于java.lang.reflect.Method.Invokenactive(本机方法)
位于java.lang.reflect.Method.invoke(Method.java:525)
在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run上(ZygoteInit.java:833)
位于com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
在dalvik.system.NativeStart.main(本机方法)
10-18 18:51:12.169 549-1386/? W/活动管理器?强制完成活动com.app.name/.activity
最简单的方法是使用调试器。在发生错误的行上放置一个断点,并找出该行上使用的变量值null
。有关详细信息,请参阅。最简单的方法是使用调试器。在发生错误的行上放置一个断点,并找出该行上使用的变量值null
。有关更多信息,请参阅。