java运算

import javax.swing.JOptionPane;
public class Addition {
	public static void main (String args[]){
		String firstNumber,secondNumber;
		int number1,number2,sum,cha,ji,chu;
		//read in first number from user as a string
		firstNumber=
				JOptionPane.showInputDialog("Enter first integer");
		
		//read in second number from user as a string
		secondNumber=
					JOptionPane.showInputDialog("Enter second integer");
		number1=Integer.parseInt(firstNumber);	
		number2=Integer.parseInt(secondNumber);
		//convert numbers from type String to int
		sum=number1+number2;
		
		cha=number1-number2;
		ji=number1*number2;
		chu=number1/number2;
		JOptionPane.showMessageDialog(null, "the sum is"+sum,"Reesults",
				JOptionPane.PLAIN_MESSAGE);
		JOptionPane.showMessageDialog(null, "the cha is"+cha,"Reesults",
				JOptionPane.PLAIN_MESSAGE);
		JOptionPane.showMessageDialog(null, "the ji is"+ji,"Reesults",
				JOptionPane.PLAIN_MESSAGE);
		JOptionPane.showMessageDialog(null, "the chu is"+chu,"Reesults",
				JOptionPane.PLAIN_MESSAGE);
		System.exit(0);
	}

}