Question

我想在计算所有视图参数后设置我的LinearLayout参数。

我正在尝试设置与父视图高度相关的LinearLayout高度。父视图的高度根据其layout_weight计算，因此我得到getMeasuredHeight();的高度

我的代码：

@Override
public void onWindowFocusChanged(boolean hasFocus) {

  super.onWindowFocusChanged(hasFocus);
  RelativeLayout lay = (RelativeLayout) findViewById(R.id.alt);
  LinearLayout bar = (LinearLayout) findViewById(R.id.barLay);

  int layH = lay.getMeasuredHeight();
  int barH = layH / 4;
  LinearLayout.LayoutParams params = (LayoutParams) bar.getLayoutParams();
  params.height = barH;
  bar.setLayoutParams(params);
}

Eclipse Debugger在此行停止程序;

LinearLayout.LayoutParams params = (LayoutParams) bar.getLayoutParams();

我找不到可能出现的问题？设置参数是否我做错了什么？

Answer 1

尝试更改此

LinearLayout.LayoutParams params = (LayoutParams) bar.getLayoutParams();

到这个

LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) bar.getLayoutParams();

Answer 2

在@LocHa问我布局的类型后，我尝试将父布局的类型更改为LinearLayout，即RelativeLayout，最后它对我有效。

Answer 3

LayoutParams的类型实际上是由视图的父级设置的，因此bar.getLayoutParams（）应该返回类型为RelativeLayout.LayoutParams的对象。通过显式转换为LinearLayout.LayoutParams，我希望您的logcat包含这样一行：

Caused by: java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams cannot be cast to android.widget.LinearLayout$LayoutParams

将其改为此应该可以解决问题：

RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) bar.getLayoutParams();

或者，由于高度属于基类，所以根本不要施放它：

ViewGroup.LayoutParams params = bar.getLayoutParams();

以编程方式设置LayoutParams

3 个答案: