Java確定哪個文本字段具有焦點

Question

我創建了按鈕1-9以及4個文本字段。 我試圖允許用戶單擊任何數字1-9以輸入到每個文本字段中。 但是，我無法確定用戶被單擊的字段。 當前1-9按鈕僅將文本輸入到amt文本字段。 如何檢查單擊了哪個字段並在其中輸入輸入？

新問題

 public void actionPerformed(ActionEvent e) {

    String iamt, ii, iterm,ipay;
    iamt = amt.getText();
    ii = interest.getText();
    iterm = term.getText();
    ipay = payment.getText();

有沒有一種方法可以縮短此if語句，使我沒有按鈕1-10的冗余代碼？

    if(e.getSource()==btn1) {
        if(previouslyFocusedTextBox.equals(amt)){
            amt.setText("1");
            amt_number+=amt.getText();
            amt.setText(amt_number); 
        }
        else if (previouslyFocusedTextBox.equals(interest)){
            interest.setText("1");
            int_number+=interest.getText();
            interest.setText(int_number);
        }
        else if (previouslyFocusedTextBox.equals(term)){
            term.setText("1");
            t_number+=term.getText();
            term.setText(t_number);
        }
        else if (previouslyFocusedTextBox.equals(payment)){
            payment.setText("1");
            p_number+=payment.getText();
            payment.setText(p_number);
        }
    }

    if(e.getSource()==btnPay){
        Loan = new LoanforCalc(Double.parseDouble(iamt),Double.parseDouble(ii),Integer.parseInt(iterm));
            payment.setText(Double.toString(Loan.getPayment())); 
    }

Answer 1

我弄清楚了OP的含義，並提出了一個快速的解決方案：

本質上，一旦單擊按鈕，文本框就會失去焦點，因此我們必須跟蹤以前的焦點。

    import java.awt.FlowLayout;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.awt.event.FocusEvent;
    import java.awt.event.FocusListener;
    import java.io.FileNotFoundException;

    import javax.swing.JButton;
    import javax.swing.JFrame;
    import javax.swing.JTextField;

    public class FocusAwareWindow extends JFrame implements ActionListener, FocusListener {
        public static void main(String[] args) throws FileNotFoundException {
            FocusAwareWindow c = new FocusAwareWindow();
        }
        private JTextField textFieldA, textFieldB;
        private JButton buttonA, buttonB;
        private JTextField previouslyFocusedTextBox = textFieldA;
        public FocusAwareWindow(){
            super();
            this.setLayout(new FlowLayout());

            textFieldA = new JTextField();
            textFieldA.setText("Field A");
            textFieldA.setFocusable(true);
            textFieldA.addFocusListener(this);
            this.add(textFieldA);

            textFieldB = new JTextField();
            textFieldB.setText("Field B");
            textFieldB.setFocusable(true);
            textFieldB.addFocusListener(this);
            this.add(textFieldB);

            buttonA = new JButton("Which is focused?");
            buttonA.addActionListener(this);
            this.add(buttonA);

            this.pack();
            this.setVisible(true);;
        }
        public void actionPerformed(ActionEvent ev) {
            if(previouslyFocusedTextBox.equals(textFieldA)){
                System.out.println("Text Field A");
            } else if(previouslyFocusedTextBox.equals(textFieldB)){
                System.out.println("Text Field B");
            }
        }
        public void focusGained(FocusEvent ev) {
            if(ev.getSource() instanceof JTextField) {
                previouslyFocusedTextBox = (JTextField) ev.getSource();
            }
        }
        public void focusLost(FocusEvent ev) {
        }
    }

Answer 2

也許添加mouseListener並在textFields上創建區域？ 只是在這里猜測，但它可能會起作用。 如果可以，那么您只需要一個變量來跟蹤您單擊的區域，然后檢查該變量中所需的textField。