java - 无法在 Framelayout 中设置 Linearlayout 参数

Question

我在 Framelayout 中有一个线性布局。我想做的是根据屏幕尺寸以编程方式向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 Activity 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Activity时出现错误

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.aba.webcampstest, PID: 11723 java.lang.ClassCastException: android.widget.LinearLayout$LayoutParams cannot be cast to android.widget.FrameLayout$LayoutParams at android.widget.FrameLayout.onMeasure(FrameLayout.java:311) at android.view.View.measure(View.java:17495) at android.widget.ScrollView.measureChildWithMargins(ScrollView.java:1779) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at android.widget.ScrollView.onMeasure(ScrollView.java:476) at android.view.View.measure(View.java:17495) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5363) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at android.view.View.measure(View.java:17495) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5363) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1410) at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) at android.view.View.measure(View.java:17495) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5363) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2548) at android.view.View.measure(View.java:17495) at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2285) at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1396) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1595) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6637) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:814) at android.view.Choreographer.doCallbacks(Choreographer.java:614) at android.view.Choreographer.doFrame(Choreographer.java:584) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:800) at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:146) at android.app.ActivityThread.main(ActivityThread.java:5602) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) at dalvik.system.NativeStart.main(Native Method)

可能是什么问题？

Answer 1

setLayoutParams description :

Set the layout parameters associated with this view. These supply parameters to the parent of this view specifying how it should be arranged. There are many subclasses of ViewGroup.LayoutParams, and these correspond to the different subclasses of ViewGroup that are responsible for arranging their children.

LayoutParams 类型应该与您的 LinearLayout 的容器相关，在本例中为 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);