Android ConstraintLayout ConstraintLayout.LayoutParams.WRAP_CONTENT 不起作用

Question

我尝试以编程方式添加 ConstraintLayout。它正在工作，但 WRAP_CONTENT 不工作。布局始终为MATCH_PARENT。

Android 开发者页面没有为 ConstraintLayout.LayoutParams 列出 WRAP_CONTENT

我的代码：

RelativeLayout rl_main = findViewById(R.id.rl_main);
ConstraintLayout cl = new ConstraintLayout(this);
cl.setId(0);
ConstraintLayout.LayoutParams clp = new ConstraintLayout.LayoutParams(ConstraintLayout.LayoutParams.WRAP_CONTENT, ConstraintLayout.LayoutParams.MATCH_CONSTRAINT_WRAP);
cl.setLayoutParams(clp);
cl.setBackgroundColor(Color.parseColor("#000000"));
rl_main.addView(cl);

Answer 1

您正在将视图 (ConstrainLayout) 添加到 RelativeLayout，因此您应该使用 RelativeLayout 参数。试试这个（同时检查你的导入是否正确）：

import android.graphics.Color;
import android.os.Bundle;
import android.widget.Button;
import android.widget.RelativeLayout;

import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;

public class MainActivity extends AppCompatActivity
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        RelativeLayout rl_main = findViewById(R.id.rl_main);
        ConstraintLayout cl = new ConstraintLayout(this);
        cl.setId(0);
        RelativeLayout.LayoutParams clp = new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

        cl.setLayoutParams(clp);
        cl.setBackgroundColor(Color.parseColor("#FF0000"));
        rl_main.addView(cl);

        //test adding button
        cl.addView(new Button(this));
    }
}

结果（红底约束布局为WRAP_CONTENT）：