java - 从 .txt 文件读取到 JFrame

Question

我一直在试图弄清楚如何将 Java 文件读入 JFrame。我需要制作一个框架并读取汽车的名称及其价格。从那里我需要计算根据用户输入的每月付款需要多长时间还清贷款。然后我必须计算利息成本是多少，利率也是由用户输入的。到目前为止，我的所有计算都正常工作，我的 JFrame 工作正常，当我单击按钮显示所有内容时，它工作正常。问题是不知道如何分别读取一个字符串和一个 double 值并进行所有计算，然后对文本文件中的任意数量的汽车和成本重复此过程。

这是我到目前为止的代码:

//Make a JFrame
//Display a heading for car name, 
//loan amount, your monthly payment, how much it costs in interest 
//and the total price of the car.

//underneath you should have all of these things outputted and being    
//read in from carLoan.txt


package myName_B10_A04_FINAL;

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import java.util.Scanner;
import java.io.*;

public class CarLoanFrame extends JFrame implements ActionListener {

CarLoan reach = new CarLoan();

String carName;
int carPrice;

private JLabel lblMonthlyPayment = new JLabel("Monthly Payment: ");
private JLabel lblInterestRate = new JLabel("Interest rate (percentage): ");
private JTextField fldMonthlyPayment = new JTextField(15);
private JTextField fldInterestRate = new JTextField(15);

private JButton btnCalculate = new JButton("Calculate now!");

private JPanel inputPanel = new JPanel();
private JTextArea areaDisplay = new JTextArea(5, 2);

public CarLoanFrame() {
    setTitle("Car Loan Calculator");

    inputPanel.add(lblMonthlyPayment);
    inputPanel.add(fldMonthlyPayment);
    inputPanel.add(lblInterestRate);
    inputPanel.add(fldInterestRate);
    inputPanel.add(btnCalculate);

    getContentPane().add(inputPanel, BorderLayout.NORTH);
    getContentPane().add(areaDisplay, BorderLayout.CENTER);

    areaDisplay.setEditable(false);
    areaDisplay.setFont(new Font("Monospaced", Font.PLAIN, 12));
    btnCalculate.addActionListener(this);
}

@Override
public void actionPerformed(ActionEvent e) {

    try {
        File integerFile = new File("carLoan.txt");
        Scanner inFile = new Scanner(integerFile);
        inFile = inFile.useDelimiter("~|\r\n");

// First Row
        String car = "Car";
        String loan = "loan";
        String monthly = "monthly";
        String number = "number of";
        String total = "total";
        String cash = "Total";
// Second Row
        String amount = "amount";
        String payment = "payment";
        String NumberPayments = "payments";
        String interest = "Interest";
        String paid = "Paid";
// Third Row
        String breaker1 = "-------------------- ";
        String breaker2 = "------------ ";
        String breaker3 = "--------- ";
        String breaker4 = "------------ ";
        String breaker5 = "------------- ";
        String breaker6 = "--------------";
// Data Row
        String carName = "\n";
// First
        areaDisplay.append(String.format("%3s", car));
        areaDisplay.append(String.format("%30s", loan));
        areaDisplay.append(String.format("%10s", monthly));
        areaDisplay.append(String.format("%13s", number));
        areaDisplay.append(String.format("%14s", total));
        areaDisplay.append(String.format("%15s", cash));
// Second
        areaDisplay.append(String.format("\n%33s", amount));
        areaDisplay.append(String.format("%10s", payment));
        areaDisplay.append(String.format("%13s", NumberPayments));
        areaDisplay.append(String.format("%14s", interest));
        areaDisplay.append(String.format("%15s", paid));
// Third
        areaDisplay.append("\n" + breaker1);
        areaDisplay.append(breaker2);
        areaDisplay.append(breaker3);
        areaDisplay.append(breaker4);
        areaDisplay.append(breaker5);
        areaDisplay.append(breaker6);

// reading the next lines
        while (inFile.hasNext()) {
            carName = inFile.next();
            carPrice = inFile.nextInt();
                
            reach.setMake(carName);
            
            
            
// Actual output
        areaDisplay.append(carName);
        
        }
        
    } // try
    catch (FileNotFoundException e1) {
        System.exit(-1);
    } // catch (FileNotFoundException e)

} // actionPerformed()

public static void main(String[] args) {

    CarLoanFrame frame = new CarLoanFrame();
    frame.setSize(650, 600);
    frame.setLocation(720, 0);
    frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
    frame.setVisible(true);
} // main()
} // CarLoanFrame class

所以 carLoan.txt 只是汽车的名称及其花费:

Honda Civic~10000
Porsche 911~50000
Chevrolet Blazer~20000
Toyota Camry~15000

然后我有另一个类，它包含我所有的构造函数、访问器、更改器(mutator)和计算方法。

package myName_B10_A04_FINAL;


public class CarLoan {
double cost, loanAmount, interest, monthlyPayment, totalInterest;
int timesPayed;
String make, model;

//  Contstructor methods
public void variables() {
    cost = 0;
    loanAmount = 0;
    interest = 0;
    monthlyPayment = 0;
    totalInterest = 0;
    timesPayed = 0;
    make = "unknown";
    model = "unknown";
}

public void variables(String ma, String mo, double loanA){
    make = ma;
    model = mo;
    loanAmount = loanA;
    
    timesPayed = 0;
    cost = 0;
    interest = 0;
    monthlyPayment = 0;
    totalInterest = 0;
}

public void variables(double monthlyP, double interestR) {
    monthlyPayment = monthlyP;
    interest = interestR;
    
    cost = 0;
    loanAmount = 0;
    totalInterest = 0;
    timesPayed = 0;
    make = "unknown";
    model = "unknown";
}

//  Accessor methods
public double getCost() {
    return cost;    
}
public double getLoanAmount() {
    return loanAmount;
}
public double getInterest() {
    return interest;
}
public double getMonthlyPayment() {
    return monthlyPayment;
}
public double getTotalInterest() {
    return totalInterest;
}
public int getTimesPayed() {
    return timesPayed;
}
public String getMake() {
    return make;
}
public String getModel() {
    return model;
}

//  Mutator methods
private void setMake(String ma) {
    make = ma;
}
private void setModel(String mo) { 
    model = mo;
}
private void setLoanAmount(double lA) {
    loanAmount = lA;
}
private void setInterest(double i) {
    interest = i;
}
private void setMonthlyPayment(double mP) {
    monthlyPayment = mP;
}

//  Calculate methods
public double calculateTotalInterest() {
    double price = 0;
    timesPayed = 0;
    double costR = 0;
    
    while (costR >= 0) {
        costR = price - monthlyPayment; 
        double x = (costR * (interest/100.0)/12.0);
        totalInterest += x;
        costR += x;
        price = (costR * 100.0) / 100.0;
        
        timesPayed++;
    }
    return totalInterest;
}
}

问题是我们取消了很多类(class)，所以我的老师没有时间向我们解释如何正确执行此操作。如果有人可以帮助我，我将非常感激。如果需要的话，我还可以更深入地了解所有内容。

Answer 1

您可以使用 BufferedReader 来读取文件的每一行。然后，您可以使用 String#split 在 ~ 分隔符上拆分 String 并解析各个元素，例如...

try (BufferedReader br = new BufferedReader(new FileReader(new File("CarLoan.txt")))) {
    String text = null;
    System.out.printf("%-20s | %s%n", "Name", "Price");
    while ((text = br.readLine()) != null) {
        String parts[] = text.split("~");
        String name = parts[0];
        int price = Integer.parseInt(parts[1]);
        System.out.printf("%-20s | %d%n", name, price);
    }
} catch (IOException ex) {
    ex.printStackTrace();
}

打印...

Name                 | Price
Honda Civic          | 10000
Porsche 911          | 50000
Chevrolet Blazer     | 20000
Toyota Camry         | 15000