How do you draw a String or Rectangle according to the screens width and Height with a Canvas in Java

I want to know How could I draw a String or Rectangle (the JFrame is in a full screen completely)

Heres what in my Main.java class:

public static int WIDTH, HEIGHT;
private Window window;
...
public Main() {
    window = new Window("2D Shooter", this);
...
    private void render(){
    BufferStrategy bs = this.getBufferStrategy();

    if(bs == null){
        this.createBufferStrategy(3);
        return;
    }

    Graphics g = bs.getDrawGraphics();

    g.setColor(Color.BLACK);
    g.fillRect(0, 0, WIDTH, HEIGHT);

    handler.render(g);//this calls the render method to render objects

    g.dispose();
    bs.show();
}

Later in a different class I have:

public void render(Graphics g){
    ...
    g.setColor(Color.WHITE);
    g.drawString("2D Shooter", ((Main.WIDTH)/2), (Main.HEIGHT/5));
    ...

}

This Code Works and runs BUT the text is not completely centered I want it to be Centered on top not in the middle. Thank You!

Solution

Use the graphics context's FontMetrics.

String s = "2D Shooter";
int w2 = g.getFontMetrics().stringWidth(s) / 2;
int h2 = g.getFontMetrics().getHeight();
g.drawString(s, getWidth() / 2 - w2, h2);

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 * @see http://stackoverflow.com/a/37150783/230513
 */
public class Test {

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setFont(getFont().deriveFont(Font.BOLD, 24f));
                String s = "2D Shooter";
                int w2 = g.getFontMetrics().stringWidth(s) / 2;
                int h2 = g.getFontMetrics().getHeight();
                g.drawString(s, getWidth() / 2 - w2, h2);
            }

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(320, 240);
            }
        });
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Test()::display);
    }
}