Here its the solution
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(0, 100);
lp.weight = 1;
See Full Solution
LinearLayout ll1, ll2, ll3;
/* Find these LinearLayout by ID
i.e ll1=(LinearLayout)findViewById(R.id.ll1);
*/
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(0, 100);
lp.weight = 1;
ll1.setLayoutParams(lp);
ll2.setLayoutParams(lp);
ll3.setLayoutParams(lp);