Android 使用LayoutParams以编程方式从FrameLayout中删除边距

我的框架布局如下所示：

 <RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <FrameLayout
        android:layout_marginTop="56dp"
        android:layout_marginBottom="50dp"
        android:id="@+id/main_frag"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

          // other stuff


     </RelativeLayout>

以下是我的尝试：

        FrameLayout fl = (FrameLayout) findViewById(R.id.main_frag);
        FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) fl.getLayoutParams();
        params.setMargins(50, 0, 0, 0);
        fl.setLayoutParams(params);

以下是

LogCat

：

04-25 16:18:08.385: E/AndroidRuntime(27682): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.---.---/com.------.---.MainFragmentActivity}: java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams cannot be cast to android.widget.FrameLayout$LayoutParams
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2314)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.access$800(ActivityThread.java:148)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.os.Handler.dispatchMessage(Handler.java:102)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.os.Looper.loop(Looper.java:135)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.main(ActivityThread.java:5312)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at java.lang.reflect.Method.invoke(Native Method)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at java.lang.reflect.Method.invoke(Method.java:372)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
04-25 16:18:08.385: E/AndroidRuntime(27682): Caused by: java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams cannot be cast to android.widget.FrameLayout$LayoutParams
04-25 16:18:08.385: E/AndroidRuntime(27682):    at com.---.---.MainFragmentActivity.onCreate(MainFragmentActivity.java:81)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.Activity.performCreate(Activity.java:5953)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1128)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2267)

---

我不明白这里是如何涉及到

RelativeLayout

的？

这个

布局参数

类是由父类而不是子类指定的。影响

FrameLayout

的

LayoutParams

是一个

RelativeLayout.LayoutParams

。影响

FrameLayout

子级的

LayoutParams

将是一个

FrameLayout。LayoutParams

是由于代码中的代码片段或错误，FrameLayout的结束标记为RelativeLayout？@Adil Error。通过将其更改为

RelativeLayout

父级已将其修复，

04-25 16:18:08.385: E/AndroidRuntime(27682): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.---.---/com.------.---.MainFragmentActivity}: java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams cannot be cast to android.widget.FrameLayout$LayoutParams
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2314)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.access$800(ActivityThread.java:148)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.os.Handler.dispatchMessage(Handler.java:102)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.os.Looper.loop(Looper.java:135)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.main(ActivityThread.java:5312)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at java.lang.reflect.Method.invoke(Native Method)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at java.lang.reflect.Method.invoke(Method.java:372)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
04-25 16:18:08.385: E/AndroidRuntime(27682): Caused by: java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams cannot be cast to android.widget.FrameLayout$LayoutParams
04-25 16:18:08.385: E/AndroidRuntime(27682):    at com.---.---.MainFragmentActivity.onCreate(MainFragmentActivity.java:81)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.Activity.performCreate(Activity.java:5953)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1128)
04-25 16:18:08.385: E/AndroidRuntime(27682):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2267)