从 JTextField 获取文本并转换为双精度

Question

如何编写代码以从 JTextField 获取文本并转换为双精度值？

我创建了一个银行账户类和一个带有amountField 的银行账户GUI 来显示我希望提取和存入的金额。 使用public void actionPerformed(ActionEvent e) 方法如何编写代码以从amountField 获取文本并转换为双精度？

我想输入帐户详细信息并能够在将值存储在字符串中的同时进行提款和存款

• 为存款按钮编写事件处理程序
• 为撤回按钮编写事件处理程序

---

public class BankAccountGUI extends JFrame implements ActionListener
{
    private Label amountLabel = new Label("Amount");
    private JTextField amountField = new JTextField(5);
    private JButton depositButton = new JButton("DEPOSIT");
    private JButton withdrawButton = new JButton("WITHDRAW");
    private Label balanceLabel = new Label("Starting Balance = 0" );

    private JPanel topPanel = new JPanel();
    private JPanel bottomPanel = new JPanel();
    private JPanel middlePanel = new JPanel();


    BankAccount myAccount = new BankAccount("James","12345");

    // declare a new BankAccount object (myAccount) with account number and name of your choice here


    public BankAccountGUI()
    {
        setTitle("BankAccount GUI");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        setSize(340, 145);
        setLocation(300,300);
        depositButton.addActionListener(this);
        withdrawButton.addActionListener(this);

        topPanel.add(amountLabel);
        topPanel.add(amountField);
        bottomPanel.add(balanceLabel);
        middlePanel.add(depositButton);
        middlePanel.add(withdrawButton);


        add (BorderLayout.NORTH, topPanel);
        add(BorderLayout.SOUTH, bottomPanel);
        add(BorderLayout.CENTER, middlePanel);

        setVisible(true);
    }


    public void actionPerformed(ActionEvent e)
    {
         //What goes here?
    }
}

Answer 1

您可能会想尝试使用 Double.parseDouble(string)。 例如：

String str = "12.0";
Double e = Double.parseDouble(str);
        System.out.println(e * 1.5); //returns 18  

Answer 2

这里有很多事情你需要做不同的事情。 简而言之，您正在寻找“JTextField.getText()”和“Double.parseDouble()”

depositButton.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        //Get the Text Value out of the UI Component
        String rawAmount=amountField.getText();

        //Convert that value to Double
        try{
            Double convertedValue = Double.parseDouble(rawAmount);
            //Do stuff with the convertedValue
        }catch(Exception e){
            System.out.println("Not A Double Value");
        }
    }
});

您还应该为每个按钮使用单独的侦听器，以免您尝试以编程方式确定哪个按钮生成了事件。

请参阅JTextField 的文档