代碼改布局的高度等Caused by: java.lang.ClassCastException: android.widget.LinearLayout$LayoutParams

來源:互聯網
上載者:User

 轉自:http://blog.163.com/smilecatflower_18z/blog/static/19262704520120974119643/最近,在android中用代碼動態改變某種布局(組件)的高度時,會遇到如題所示的類轉換異常。上網查了一下,如下所示:

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.

So basically, if you are adding a view to another, you MUST set the LayoutParams of the view to the LayoutParams type that the parent uses, or you will get a runtime error.

 我是這樣理解的,如果你要將一個view添加到另一個布局中,你必須設定該View的布局參數為其父類所使用的布局參數類型。即要在代碼中動態改變某組件的高度,其布局參數類型應該是其父類所使用的布局參數類型。

 比如:

<LinearLayout

  xmlns:android="http://schemas.android.com/apk/res/android"  

  android:layout_width="wrap_content"

  android:layout_height="wrap_content">  

  

<FrameLayout 

android:id="@+id/FrameLayout01" 

android:layout_width="wrap_content" 

android:layout_height="wrap_content" />

</LinearLayout>

若想在代碼中動態改變FrameLayout的大小,應該這樣寫:

FrameLayout frameLayout=(FrameLayout) convertView.findViewById(R.id.FrameLayout01);
 

 LinearLayout.LayoutParams ff=new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, height);

frameLayout.setLayoutParams(ff);

註:其布局參數類型應該線性布局LinearLayout.LayoutParams的類型,而不是幀布局FrameLayout .LayoutParams。

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