//Addition program that use JOptionPane for input and output. import javax.swing.JOptionPane; public class Addition{ public static void main(String[] args) { String firstNumber=JOptionPane.showInputDialog("Enter first integer!"); String secondNu
import java.util.*; import javax.swing.JOptionPane; import javax.swing.UIManager; public class Main { public static void main (String args[]){ try{ UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); /* * 这段try-catch代码的功能是: 把程序界面