算利息

import javax.swing.JOptionPane;


public class Interest {
    public static void main(String[] args){
        double accrual;
        String input = JOptionPane.showInputDialog(null,"请输入收支余额：");
        String input1 = JOptionPane.showInputDialog(null,"请输入利息率：");
        double balance = Double.parseDouble(input);
        double interest = Double.parseDouble(input1);
        accrual = (int)(balance * (interest / 1200) * 100) / 100.00;
        JOptionPane.showMessageDialog(null, "The interest is " + accrual);
    }
        
}

利用下面的公式计算下月的利息额

利息额=收支余额*（年利率/1200）