如何动态地将线性布局（作为子项）添加到约束布局（父级）？

Question

I defined a method to create a linear layout and to add it to parent layout. But it didn't work. I think I made mistake(s).

    public void methodName() {
        LinearLayout linearLayout = new LinearLayout(MainActivity.this);
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
        linearLayout.setLayoutParams(params);
        linearLayout.setOrientation(LinearLayout.HORIZONTAL);
        linearLayout.setBackgroundColor(Color.RED);
        ConstraintLayout main = (ConstraintLayout) findViewById(R.id.mainLayout);
        main.addView(linearLayout);
   }

Answer 1

To add views to a ConstraintLayout you have to add the constraints using a ConstraintSet.

While Adding dynamic views to constraint layout, it is a bit different from other layouts. You need to specify the constraints as well like this below:-

     ConstraintLayout main = (ConstraintLayout) findViewById(R.id.mainLayout);
     ConstraintSet set = new ConstraintSet();

     LinearLayout linearLayout = new LinearLayout(MainActivity.this);
     LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
     linearLayout.setLayoutParams(params);
     linearLayout.setOrientation(LinearLayout.HORIZONTAL);
     linearLayout.setBackgroundColor(Color.RED);
     main.addView(linearLayout,0);
     set.clone(main);
     set.connect(linearLayout.getId(), ConstraintSet.TOP, main.getId(), ConstraintSet.TOP, 60);
     set.applyTo(main);