Java 创建一个窗口，使其启动时位于屏幕中间

import java.awt.Toolkit;

import javax.swing.JFrame;

public class WindowInTheMiddle extends JFrame {
    public static void main(String[] args) {
        WindowInTheMiddle window = new WindowInTheMiddle();
        window.launchFrame();
    }
    
    public void launchFrame() {
        // The width & Height of the window
        final int formWidth = 500;
        final int formHeight = 500;
        // The width & Height of the screen
        int screenWidth = (int)Toolkit.getDefaultToolkit().getScreenSize().getWidth();
        int screenHeight = (int)Toolkit.getDefaultToolkit().getScreenSize().getHeight();
        
        // Set title, size, location & visible
        this.setTitle("Hello World! I'm coming!");
        this.setSize(formWidth, formHeight);
        this.setLocation((screenWidth-formWidth)/2, (screenHeight-formHeight)/2);
        this.setVisible(true);
    }
}