Android：以编程方式设置线性布局高度

我正试图从活动中创建一个新的LinearLayout，以将其插入另一个视图中，这就是我的做法

LinearLayout linearLayout = new LinearLayout(this);
linearLayout.setOrientation(LinearLayout.VERTICAL);
linearLayout.setBackgroundResource(R.color.customBlue);
linearLayout.getLayoutParams().height= ViewGroup.LayoutParams.WRAP_CONTENT;
linearLayout.getLayoutParams().width= ViewGroup.LayoutParams.MATCH_PARENT;

但是我得到了这个错误

java.lang.NullPointerException: Attempt to write to field 'int
android.view.ViewGroup$LayoutParams.height' on a null object reference

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那么，如何以编程方式设置LinearLayout width和height以匹配\u parent或wrap\u内容呢？这里的错误是什么？

您做错了，您试图设置空布局参数高度，因为您在创建布局对象后没有将布局参数设置为LinearLayout

ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
linearLayout.setLayoutParams(params);

LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.VERTICAL); 
ll.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.MATCH_PARENT));

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