Question

我在Framelayout中有一个线性布局。我想要做的是根据屏幕尺寸以编程方式为线性布局添加一些边距。

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true"
    android:scrollbars="none">
    <FrameLayout 
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.example.aba.webcampstest.MainActivity"
        android:orientation="vertical">

        <ImageView
            android:id="@+id/headerImageView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:adjustViewBounds="true"
            android:layout_marginTop="0dp"
            android:scaleType="centerCrop"/>

        <LinearLayout
            android:id="@+id/mainContainerLayout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

         //oher stuffs
       </LinearLayout>
    </FrameLayout >
</ScrollView>

我的活动onCreate方法包含

LinearLayout containerLayout = (LinearLayout) findViewById(R.id.mainContainerLayout);
int marginTopBottom = dpToPx((int)((dpHeight*8)/100),(int)density); //8%
int marginLeftRight = dpToPx((int)((dpWidth*6)/100),(int)density); //6%

LinearLayout.LayoutParams languageContainerLayoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
languageContainerLayoutParams.setMargins(marginLeftRight,marginTopBottom,marginLeftRight,marginTopBottom);
containerLayout.setLayoutParams(languageContainerLayoutParams);

启动活动时出现错误

E / AndroidRuntime：致命异议：主要过程：com.example.aba.webcampstest，PID：11723 java.lang.ClassCastException：android.widget.LinearLayout $ LayoutParams无法强制转换为 android.widget.FrameLayout $的LayoutParams 在android.widget.FrameLayout.onMeasure（FrameLayout.java:311）在android.view.View.measure（View.java:17495）在android.widget.ScrollView.measureChildWithMargins（ScrollView.java:1779）在android.widget.FrameLayout.onMeasure（FrameLayout.java:310）在android.widget.ScrollView.onMeasure（ScrollView.java:476）在android.view.View.measure（View.java:17495）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5363）在android.widget.FrameLayout.onMeasure（FrameLayout.java:310）在android.view.View.measure（View.java:17495）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5363）在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1410）在android.widget.LinearLayout.measureVertical（LinearLayout.java:695）在android.widget.LinearLayout.onMeasure（LinearLayout.java:588）在android.view.View.measure（View.java:17495）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5363）在android.widget.FrameLayout.onMeasure（FrameLayout.java:310）在com.android.internal.policy.impl.PhoneWindow $ DecorView.onMeasure（PhoneWindow.java:2548）在android.view.View.measure（View.java:17495）在android.view.ViewRootImpl.performMeasure（ViewRootImpl.java:2285）在android.view.ViewRootImpl.measureHierarchy（ViewRootImpl.java:1396）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1595）在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1254）在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:6637）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:814）在android.view.Choreographer.doCallbacks（Choreographer.java:614）在android.view.Choreographer.doFrame（Choreographer.java:584）在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:800）在android.os.Handler.handleCallback（Handler.java:733）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:146）在android.app.ActivityThread.main（ActivityThread.java:5602） at java.lang.reflect.Method.invokeNative（Native Method）在java.lang.reflect.Method.invoke（Method.java:515）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1283）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1099）在dalvik.system.NativeStart.main（本地方法）

可能是什么问题？

Answer 1

setLayoutParams description：

设置与此视图关联的布局参数。这些供应参数指向此视图的父级，指定应如何排列。 ViewGroup.LayoutParams有许多子类，它们对应于负责安排子节点的ViewGroup的不同子类。

LayoutParams类型应该相对于LinearLayout的容器，在这种情况下FrameLayout.LayoutParams：

FrameLayout.LayoutParams languageContainerLayoutParams = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT);
languageContainerLayoutParams.setMargins(marginLeftRight,marginTopBottom,marginLeftRight,marginTopBottom);
containerLayout.setLayoutParams(languageContainerLayoutParams);

Answer 2

更仔细地阅读例外，尤其是这一部分：

java.lang.ClassCastException：android.widget.LinearLayout $ LayoutParams无法强制转换为android.widget.FrameLayout $ LayoutParams

为了澄清，在设置视图的LayoutParams时，您要声明视图在其父元素中的位置。

因此，对于此示例，您提供了使用FrameLayout.LayoutParams。

根据第一条评论更新基础：

让我举个例子：

LinearLayout containerLayout = (LinearLayout) 

findViewById(R.id.mainContainerLayout);
int marginTopBottom = dpToPx((int)((dpHeight*8)/100),(int)density); //8%
int marginLeftRight = dpToPx((int)((dpWidth*6)/100),(int)density); //6%

FrameLayout.LayoutParams languageContainerLayoutParams = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT);
languageContainerLayoutParams.setMargins(marginLeftRight,marginTopBottom,marginLeftRight,marginTopBottom);
containerLayout.setLayoutParams(languageContainerLayoutParams);

您正在为LinearLayout设置参数，但该布局位于FrameLayout内。因此LinearLayout的LayoutParams属于FrameLayout.LayoutParams类型。

您应该使用哪种类型的LayoutParams基于您的视图所在的父类型。

Answer 3

Hello @Coder请检查此代码片段是否可行

LinearLayout containerLayout = (LinearLayout) findViewById(R.id.mainContainerLayout);
int marginTopBottom = dpToPx((int)((dpHeight*8)/100),(int)density); //8%
int marginLeftRight = dpToPx((int)((dpWidth*6)/100),(int)density); //6%

ViewGroup.LayoutParams layoutParams = containerLayout.getLayoutParams();
((ViewGroup.MarginLayoutParams) layoutParams).topMargin=marginTopBottom;
((ViewGroup.MarginLayoutParams) layoutParams).bottomMargin=marginTopBottom;
((ViewGroup.MarginLayoutParams) layoutParams).leftMargin=marginLeftRight;
((ViewGroup.MarginLayoutParams) layoutParams).rightMargin=marginLeftRight;
containerLayout.setLayoutParams(layoutParams);

无法在Framelayout

3 个答案: