int android.view.View.getImportantForAccessibility()

最新推荐文章于 2020-10-14 17:20:12 发布
原创 最新推荐文章于 2020-10-14 17:20:12 发布 · 1.7k 阅读 · 0 ·
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本文详细解析了在Adapter的getView方法中返回null时触发的NullPointerException异常原因，及如何避免此异常的发生，确保Android应用的稳定运行。

在这里插入图片描述
在adapter中getView的View返回null的时候就报这个异常
java.lang.NullPointerException: Attempt to invoke virtual method ‘int android.view.View.getImportantForAccessibility()’ on a null object reference

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Nul int android.view.View.getImportantForAccessibility() 空指针
sinat_34426699的博客
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08-15 19:45:18.824: E/CrashReport(3849): java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference在使用listview的时...
int android.view.View.getImportantForAccessibility()’ on a null object reference
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1. 错误描述： Attempt to invoke virtual method ‘int android.view.View.getImportantForAccessibility()’ on a null object reference 2. 错误原因： 应该是自定义的Adapter的getView()返回值 为null; 3. 解决方案： Adapter的getView() 返回view; ...
Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility() 解决方案
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此问题由adapter的getview引发 主要由于getview返回 convertview返回为null, 当判断covert!=null时 inflate.from()后 仍然报错 我们倒退一步,先来看看这个adapter是为什么类型的listview 设计的 首先这个adapter的item是只显示一种,还是有多种类型 A.当只有一种布局 则不用覆写getviewtype(int...
Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()
hilaochen的专栏
03-21 1976
最近在写一个列表界面，平时屡试不爽Adapter发现突然不灵了，总是如下的错误： Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility() 百思不得其解。最后在这篇文章道客优里找到了解决办法 恨自己不细心 ...
int android.view.View.getImportantForAccessibility()' on a null object reference
06-02
### Android中解决`getImportantForAccessibility`方法出现的空指针异常 在Android开发中，`NullPointerException`通常是由于尝试调用一个为`null`的对象的方法或访问其属性所导致的。当使用`View....
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference
06-01
int importance = view.getImportantForAccessibility(); // 进一步处理 importance } else { Log.e("Error", "View object is null"); } ``` #### 2. 检查视图初始化逻辑 如果 `View` 是通过动态创建或绑定的...
java.lang.nullpointerexception: attempt to invoke virtual method 'int android.view.view.getimportantforaccessibility()' on a null object reference
03-16
具体来说，它尝试在一个空的View对象上调用getImportantForAccessibility()方法。这可能是因为您没有正确初始化或分配对象，或者因为对象已被销毁或释放。要解决此错误，请确保正确初始化和分配对象，并在使用对象...
package com.st.launcher.util; import android.content.Context; import android.util.AttributeSet; import android.view.MotionEvent; import androidx.viewpager.widget.ViewPager; public class ControlSlideViewPager extends ViewPager { public ControlSlideViewPager(Context context) { super(context); } public ControlSlideViewPager(Context context, AttributeSet attrs) { super(context, attrs); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { return false; } @Override public boolean onTouchEvent(MotionEvent ev) { return false; } } public ViewPager(@NonNull Context context) { super(context); initViewPager(); } public ViewPager(@NonNull Context context, @Nullable AttributeSet attrs) { super(context, attrs); initViewPager(); } void initViewPager() { setWillNotDraw(false); setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); setFocusable(true); final Context context = getContext(); mScroller = new Scroller(context, sInterpolator); final ViewConfiguration configuration = ViewConfiguration.get(context); final float density = context.getResources().getDisplayMetrics().density; mTouchSlop = configuration.getScaledPagingTouchSlop(); mMinimumVelocity = (int) (MIN_FLING_VELOCITY * density); mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); mLeftEdge = new EdgeEffect(context); mRightEdge = new EdgeEffect(context); mFlingDistance = (int) (MIN_DISTANCE_FOR_FLING * density); mCloseEnough = (int) (CLOSE_ENOUGH * density); mDefaultGutterSize = (int) (DEFAULT_GUTTER_SIZE * density); ViewCompat.setAccessibilityDelegate(this, new MyAccessibilityDelegate()); if (ViewCompat.getImportantForAccessibility(this) == ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) { ViewCompat.setImportantForAccessibility(this, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES); } ViewCompat.setOnApplyWindowInsetsListener(this, new androidx.core.view.OnApplyWindowInsetsListener() { private final Rect mTempRect = new Rect(); @Override public WindowInsetsCompat onApplyWindowInsets(final View v, final WindowInsetsCompat originalInsets) { // First let the ViewPager itself try and consume them... final WindowInsetsCompat applied = ViewCompat.onApplyWindowInsets(v, originalInsets); if (applied.isConsumed()) { // If the ViewPager consumed all insets, return now return applied; } // Now we'll manually dispatch the insets to our children. Since ViewPager // children are always full-height, we do not want to use the standard // ViewGroup dispatchApplyWindowInsets since if child 0 consumes them, // the rest of the children will not receive any insets. To workaround this // we manually dispatch the applied insets, not allowing children to // consume them from each other. We do however keep track of any insets // which are consumed, returning the union of our children's consumption final Rect res = mTempRect; res.left = applied.getSystemWindowInsetLeft(); res.top = applied.getSystemWindowInsetTop(); res.right = applied.getSystemWindowInsetRight(); res.bottom = applied.getSystemWindowInsetBottom(); for (int i = 0, count = getChildCount(); i < count; i++) { final WindowInsetsCompat childInsets = ViewCompat .dispatchApplyWindowInsets(getChildAt(i), applied); // Now keep track of any consumed by tracking each dimension's min // value res.left = Math.min(childInsets.getSystemWindowInsetLeft(), res.left); res.top = Math.min(childInsets.getSystemWindowInsetTop(), res.top); res.right = Math.min(childInsets.getSystemWindowInsetRight(), res.right); res.bottom = Math.min(childInsets.getSystemWindowInsetBottom(), res.bottom); } // Now return a new WindowInsets, using the consumed window insets return applied.replaceSystemWindowInsets( res.left, res.top, res.right, res.bottom); } }); } ------------------------ 这是viewpager的代码 package com.st.launcher.util; import android.content.Context; import android.content.res.Resources; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.view.MotionEvent; import android.view.ViewConfiguration; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mockito; import static org.junit.Assert.assertFalse; import static org.mockito.ArgumentMatchers.any; import static org.mockito.ArgumentMatchers.contains; import static org.powermock.api.mockito.PowerMockito.mock; import static org.powermock.api.mockito.PowerMockito.mockStatic; import static org.powermock.api.mockito.PowerMockito.when; import androidx.viewpager.widget.ViewPager; import java.lang.reflect.Field; @RunWith(org.powermock.modules.junit4.PowerMockRunner.class) @org.powermock.core.classloader.annotations.PrepareForTest({ControlSlideViewPager.class, ViewConfiguration.class}) public class ControlSlideViewPagerTest { @Test public void testOnInterceptTouchEvent_ReturnsFalse() throws Exception{ mockStatic(ViewConfiguration.class); // 创建一个 mock 的 Context（虽然不会实际使用） Context mockContext = Mockito.mock(Context.class); when(ViewConfiguration.get(any())).thenReturn(mock(ViewConfiguration.class)); ViewPager mockViewPager = mock(ViewPager.class); Context mock = mock(Context.class); DisplayMetrics displayMetrics = mock(DisplayMetrics.class); Resources resources = mock(Resources.class); when(mockViewPager.getContext()).thenReturn(mock); when(mock.getResources()).thenReturn(resources); when(resources.getDisplayMetrics()).thenReturn(displayMetrics); Field declaredField = DisplayMetrics.class.getDeclaredField("density"); declaredField.setAccessible(true); declaredField.set(displayMetrics,1); // 构造被测试的对象 ControlSlideViewPager viewPager = new ControlSlideViewPager(mockContext); // 调用方法 MotionEvent mockEvent = Mockito.mock(MotionEvent.class); boolean result = viewPager.onInterceptTouchEvent(mockEvent); // 验证返回值 assertFalse(result); } @Test public void testOnTouchEvent_ReturnsFalse() { // 创建一个 mock 的 Context Context mockContext = Mockito.mock(Context.class); // 构造被测试的对象 ControlSlideViewPager viewPager = new ControlSlideViewPager(mockContext); // 调用方法 MotionEvent mockEvent = Mockito.mock(MotionEvent.class); boolean result = viewPager.onTouchEvent(mockEvent); // 验证返回值 assertFalse(result); } @Test public void testConstructor_TwoParams_DoesNotThrow() { // 创建 mocks Context mockContext = Mockito.mock(Context.class); AttributeSet mockAttrs = Mockito.mock(AttributeSet.class); // 构造对象 ControlSlideViewPager viewPager = new ControlSlideViewPager(mockContext, mockAttrs); // 如果没有抛出异常，则测试通过 } } 为什么这样mock还是会报错
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你当前的测试代码尝试使用 **PowerMock + Mockito** 来 mock Android SDK 的类（如 `Context`、`Resources`、`DisplayMetrics`、`ViewConfiguration` 等），但在某些场景下 mock 并未正确生效，尤其是在 `ViewPager`...
Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()'
purse_dream的博客
06-24 1048
Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference 使用适配器时，运行出现这错误，这是因为你的适配器中的getView()返回为null ...
[已解决]Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()'
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写错词； 没有返回view 所以报空指针异常
Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null ob
AntDream的程序世界
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今天碰到个奇怪的错误 Attempt to invoke virtual method ‘int android.view.View.getImportantForAccessibility()’ on a null object reference 百思不得其解，就简单一个页面，一个列表。找来找去，原因真是让人泪奔。。。 各位碰到这个问题的看官，请检查一下你的Adapter的getView方法是...
Attempt to invoke virtual method ‘int android.view.View.getImportantForAccessibility()‘ on a null ob
cyunann的博客
10-14 256
附上报错 这问题就是适配器adapter返回null，查看一下你getView()方法中的view返回是否已实现
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportant
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java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object referencegetView()方法返回null,会造成这个异常改成convertView就行@Override publ...
Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()解决fang'f
porken的博客
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写了一个Adapter适配器，调用的时候报错： java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference at and
error: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getIm
qq_15867901的博客
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error: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference 错误原因 ，getView（）方法返回为空，仔细查看getview方法，注意添加非空判断即
android.view.SurfaceTexture 有吗
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另外，引用[2]中提到了Surface和SurfaceControl，它们分别位于android.view和android.view包（Surface在android.view包，SurfaceControl在android.view或android.view.SurfaceControl，取决于API级别），但这与...
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