Android 代码动态设置margin（报错：ViewGroup$MarginLayoutParams cannot be cast to android.widget.LinearLayout）

Android 动态设置margin问题解决

最新推荐文章于 2023-09-07 15:17:39 发布

原创最新推荐文章于 2023-09-07 15:17:39 发布 · 3k 阅读

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博客介绍了在Android开发中遇到动态设置margin时出现的类型转换错误，重点讲解了解决这一问题的关键if语句判断，防止直接使用ViewGroup.MarginLayoutParams导致的运行时异常。

ViewGroup.LayoutParams params = recyclerView.getLayoutParams();
ViewGroup.MarginLayoutParams marginParams = null;
//获取view的margin设置参数
    if (params instanceof ViewGroup.MarginLayoutParams) {
        marginParams = (ViewGroup.MarginLayoutParams) params;
    } else {
//不存在时创建一个新的参数
//基于View本身原有的布局参数对象
marginParams = new ViewGroup.MarginLayoutParams(params);
    }
marginParams.setMargins(0,0,1,0);

千万记住这里面的if 语句的判断，如果直接marginParams = new ViewGroup.MarginLayoutParams(params); 会报错

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: kodulf.swiperefreshlayoutrecyclerviewdemo, PID: 14673
    java.lang.ClassCastException: android.view.ViewGroup$MarginLayoutParams cannot be cast to android.widget.LinearLayout$LayoutParams
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:779)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:685)
        at android.view.View.measure(View.java:22093)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6614)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1514)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:806)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:685)
        at android.view.View.measure(View.java:22093)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6614)