Java学习之GUI界面应用程序

雨点打透心脏的1/2处 2022-11-11 05:19 156阅读 0赞

**一、基本知识：**

我们在Java中编码时，除了从控制台输入，还可以通过调用JOptionPane.showInputDialog()方法从一个输入对话框中获取输入。

**二、贷款案例**

我们举一个贷款案例：利用输入对话框计算贷款支付额。  
假设年利率：6.25，贷款年数：20，贷款总额：25000。

**案例代码**

import javax.swing.JOptionPane;
    public class ComputeLoanUsingInputDialog {
        
    	public static void main(String[] args) {
        
    	String annualInterestRateString = JOptionPane.showInputDialog("Enter yearly interest rate, for example 8.25:");
    	double annualInterestRate = Double.parseDouble(annualInterestRateString);
    	double monthlyInterestRate = annualInterestRate/1200;
    	String numberOfYearsString = JOptionPane.showInputDialog("Enter number of years as an integer,\n for example 5:");
    	int numberOFYears = Integer.parseInt(numberOfYearsString);
    	String loanString = JOptionPane.showInputDialog("Enter loan mount,for example 120000.95:");
    	double loanAmount = Double.parseDouble(loanString);
    	double monthlyPayment = loanAmount * monthlyInterestRate/(1-1/Math.pow(1+monthlyInterestRate,numberOFYears*12));
    	double totalPayment = monthlyPayment * numberOFYears*12;
    	monthlyPayment = (int)(monthlyPayment * 100) / 100.0;
    	totalPayment = (int)(totalPayment * 100)/100.0;
    	String output = "The monthly payment is "+monthlyPayment+"\n The total payment is " + totalPayment;
    	JOptionPane.showMessageDialog(null,output);
    	}
    }

**案例效果图：**

（1）输入年利率：6.25

![在这里插入图片描述][20210319135329753.png_pic_center]

（2）输入贷款年数：20

![在这里插入图片描述][20210319135549386.png_pic_center]

（3）输入贷款总额：25000

![在这里插入图片描述][2021031913563381.png_pic_center]

（4）计算月支付额度和总支付额度：

![在这里插入图片描述][20210319135712165.png_pic_center]

[20210319135329753.png_pic_center]: /images/20221022/cac9475198d543aa92982b4d9f2dafe9.png
[20210319135549386.png_pic_center]: /images/20221022/ed7230df99ee4b17be6f56ccd07d7fee.png
[2021031913563381.png_pic_center]: /images/20221022/da3f4315e08649c7b4c33c15d81765fb.png
[20210319135712165.png_pic_center]: /images/20221022/6e365e6aee7e424b8eba67eb1dd67a53.png