MainActivity.java

package com.lakhanpal.ankit.alison;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.RelativeLayout;
import android.widget.Button;
import android.graphics.Color;
import android.widget.EditText;
import android.content.res.Resources;
import android.util.TypedValue;
import org.w3c.dom.Text;


public class MainActivity extends AppCompatActivity {

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

        //converting px type to dip

        //( Resources r=getResources();   //get information about phone ) -> we don't need this object (;
        int px=(int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,200,getResources.getDisplayMetrics());


        //Button
        Button redbutton= new Button(this);
        RelativeLayout.LayoutParams buttonDetails= new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.WRAP_CONTENT
        );
        buttonDetails.addRule(RelativeLayout.CENTER_HORIZONTAL);
        buttonDetails.addRule(RelativeLayout.CENTER_VERTICAL);
        RelativeLayout AnkitsLayout=new RelativeLayout(this);
        redbutton.setText("login");
        redbutton.setBackgroundColor(Color.CYAN);
        redbutton.setId(1);


        //Text
        EditText username = new EditText(this);
        RelativeLayout.LayoutParams usernameDetails =new RelativeLayout.LayoutParams(
        RelativeLayout.LayoutParams.WRAP_CONTENT,
        RelativeLayout.LayoutParams.WRAP_CONTENT
        );
        usernameDetails.addRule(RelativeLayout.ABOVE, redbutton.getId());
        usernameDetails.addRule(RelativeLayout.CENTER_HORIZONTAL);
        usernameDetails.setMargins(0, 0, 0, 50);
        username.setWidth(px);

        AnkitsLayout.setId(2);
        AnkitsLayout.addView(redbutton, buttonDetails);
        AnkitsLayout.setBackgroundColor(Color.BLUE);
        AnkitsLayout.addView(username, usernameDetails);
        setContentView(AnkitsLayout);//set the content after last addView method.



    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}