android_create_view_by_java.java

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        RelativeLayout rl = new RelativeLayout(this);
        rl.setBackgroundColor(Color.BLUE);

        Button btn = new Button(this);
        btn.setId(1);
        btn.setText("Press Me");
        btn.setBackgroundColor(Color.YELLOW);

        RelativeLayout.LayoutParams params_btn = new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.WRAP_CONTENT
        );
        params_btn.addRule(RelativeLayout.CENTER_HORIZONTAL);
        params_btn.addRule(RelativeLayout.CENTER_VERTICAL);

        EditText et = new EditText(this);
        et.setId(2);
        int _px = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 200,
                getResources().getDisplayMetrics());
        et.setWidth(_px);

        RelativeLayout.LayoutParams params_et = new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.WRAP_CONTENT
        );
        params_et.addRule(RelativeLayout.ABOVE, btn.getId());
        params_et.addRule(RelativeLayout.CENTER_HORIZONTAL);
        params_et.setMargins(0, 0, 0, 80);

        rl.addView(btn, params_btn);
        rl.addView(et, params_et);
        setContentView(rl);
    }
}