how to set setLayoutParams for linear layout elements

Question

How to set setLayoutParams() for LinearLayout elements. in MainActivity.java. I wrote the following code for set Layout params and

Answer 1

imageview1.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, 50));  
textview1.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, 50));
listview01.setLayoutParams(new
       LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT));

Answer 2

Try this in onCreate at the beginning of your activity (should replace the pic though). Don't forget to comment the setContentView that comes by default:

// setContentView(R.layout.activity_main);

TextView label = new TextView(this);
label.setText("This is working, congrats!");
label.setTextSize(20);
label.setGravity(Gravity.CENTER_HORIZONTAL);

LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.VERTICAL);
ll.setLayoutParams(new WindowManager.LayoutParams());

ll.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT));
ll.setGravity(Gravity.CENTER);
ll.addView(label);
setContentView(ll);