別のテキストボックスに操作を帰後のJLabelで出力を表示するには？

Nonstopbrain：

私は現在、テキストボックスにし、それを右に私の入力操作は、ボタンがあり電卓を作ってるんです。私は、テキストボックスに入力して押したり、ボタンを押すと、解答やエラーメッセージがJLabelのの下に表示されるはずです。私は多少の入力テキストボックスとボタンを表示することができるよしかし、ボタンがクリックされたか、ラベルに押されて入ると解答を表示する方法がわかりません。

ビューア

import javax.swing.JFrame;

public class CalculatorViewer {

    public static void main(String[] args) {
        JFrame frame = new CalculatorViewerFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("FontViewer");
        frame.setVisible(true);
    }

}

フレーム

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class CalculatorViewerFrame extends JFrame {
       private JLabel resultLabel;
       private JTextField inputField;
       private JButton button;
       private ActionListener listener;

       private static final int FRAME_WIDTH = 500;
       private static final int FRAME_HEIGHT = 300;

       public CalculatorViewerFrame() {
           class Calculate implements ActionListener {
               public void actionPerformed(ActionEvent event) {
                   String input = inputField.getText();
                   input = input.trim();
                   int x = 0,y=0;
                   String operator;
                   try {
                       x = Integer.parseInt(input.substring(0,input.indexOf(" ")));
                   } catch(InvalidExpressionException exception) {
                          resultLabel.setText("The first operand is not an integer");
                   }
                   if (input.indexOf(" ")==input.lastIndexOf(" ") || input.indexOf(" ")+1==input.lastIndexOf(" ")) {
                       operator = " ";
                   } else {
                       operator = input.substring(input.indexOf(" "), input.lastIndexOf(" "));
                   }
                   operator = operator.trim();
                   try {
                       y= Integer.parseInt(input.substring(input.lastIndexOf(" ")));
                   } catch(InvalidExpressionException exception) {
                       resultLabel.setText("The second operand is not an integer");
                   }
                   int answer;
                   String operation = x +" " + operator + y+ " = ";
                   switch (operator) {
                    case "+": answer = x + y;
                    resultLabel.setText(operation + answer);
                    resultLabel.repaint();
                    case "-": answer = x - y;
                    resultLabel.setText(operation + answer);
                    resultLabel.repaint();
                    case "*": answer = x * y;
                    switch (y) {
                    case 0: resultLabel.setText("Cannot divide by 0");
                    }
                    resultLabel.setText(operation + answer);
                    resultLabel.repaint();
                    case "/": answer = x / y;
                    resultLabel.setText(operation + answer);
                    resultLabel.repaint();
                    case "%": answer = x % y;
                    resultLabel.setText(operation + answer);
                    resultLabel.repaint();
                    default: resultLabel.setText("Illegal operator");
                   }
               }
           }

           createInputPanel();
           resultLabel = new JLabel();
           add(resultLabel, BorderLayout.CENTER);
           listener = new Calculate();

           setSize(FRAME_WIDTH, FRAME_HEIGHT);
       }


       public void createInputPanel() {
           JPanel inputPanel = createInputTextField();
           JPanel compute = createButton();

           JPanel controlPanel = new JPanel();
           controlPanel.setLayout(new GridLayout(1,2));
           controlPanel.add(inputPanel);
           controlPanel.add(compute);

           add(controlPanel, BorderLayout.NORTH);
       }

       private JPanel createInputTextField() {
           inputField = new JTextField(20);
           inputField.setEditable(true);
           inputField.requestFocus();
           inputField.setText("");
           JPanel panel = new JPanel();
           inputField.addActionListener(listener);
           panel.add(inputField);
           return panel;
       }

       public JPanel createButton() {
           button = new JButton("Compute");
           JPanel panel = new JPanel();
           button.addActionListener(listener);
           panel.add(button);
           return panel;
       }
}

ここでは次のように/のようになります。何の絵です。

すべてのヘルプは大歓迎です！ありがとうございました。

Jhaytootz・トーレス：

私はスーパー彼のフィードバックにScheintodに同意します。彼はそれを釘付けように私は彼にそれを残します。私はあなたのコードを最適化するために管理しました。コード内の私のコメントを参照してください、それから学びます。私はそれが、これはあなたの宿題/プロジェクトであると思いますか？笑。

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class CalculatorViewerFrame extends JFrame implements ActionListener { // you dont need to create sub class and
                                                                                // implement ActionListener to it. You
                                                                                // can do it here
    private JLabel resultLabel;
    private JTextField inputField;
    private JButton button;

    private static final int FRAME_WIDTH = 500;
    private static final int FRAME_HEIGHT = 300;

    public CalculatorViewerFrame() {
        createInputPanel();
        resultLabel = new JLabel();
        add(resultLabel, BorderLayout.CENTER);

        setSize(FRAME_WIDTH, FRAME_HEIGHT);
    }

    private void createInputPanel() { // set your modifier into private, it is not used from other class
        JPanel inputPanel = createInputTextField();
        JPanel compute = createButton();

        JPanel controlPanel = new JPanel();
        controlPanel.setLayout(new GridLayout(1, 2));
        controlPanel.add(inputPanel);
        controlPanel.add(compute);

        add(controlPanel, BorderLayout.NORTH);
    }

    private JPanel createInputTextField() {
        inputField = new JTextField(20);
        inputField.setEditable(true);
        inputField.requestFocus();
        inputField.setText("");
        JPanel panel = new JPanel();
        inputField.addActionListener(this); // since you implemented it to this class. you can use `this` as your input in parameter addActionListener
        panel.add(inputField);
        return panel;
    }

    private JPanel createButton() { // set your modifier into private, it is not used from other class
        button = new JButton("Compute");
        JPanel panel = new JPanel();
        button.addActionListener(this); // same thing with line 50
        panel.add(button);
        return panel;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getActionCommand().equals("Compute")) { // though you have only one action. always check for this as it
                                                        // tells what action event happened.
            // parse and validate
            String input = inputField.getText();
            input = input.trim();
            int x = 0, y = 0;
            String operator;

            try {
                x = Integer.parseInt(input.substring(0, input.indexOf(" ")).trim());
            } catch (NumberFormatException exception) { // check your catch exception too. Remove that is/are not relevant to your try block
                resultLabel.setText("The first operand is not an integer");
                return; // you need to stop the process from here. you are using resultLabel all the time and you setText into it.
            }

            if (input.indexOf(" ") == input.lastIndexOf(" ") || input.indexOf(" ") + 1 == input.lastIndexOf(" ")) {
                operator = " ";
            } else {
                operator = input.substring(input.indexOf(" "), input.lastIndexOf(" "));
            }
            operator = operator.trim();

            try {
                y = Integer.parseInt(input.substring(input.lastIndexOf(" ")).trim()); // trim for white spaces.
            } catch (NumberFormatException exception) {
                resultLabel.setText("The second operand is not an integer");
                return; // you need to stop the process from here. you are using resultLabel all the time and you setText into it.
            }

            compute(x, y, operator);
        }
    }

    private void compute(int x, int y, String operator) { // you can move this block of code into another method as it
                                                            // is a new process.
        int answer;
        String operation = x + " " + operator + y + " = ";
        switch (operator) {
        case "+":
            answer = x + y;
            resultLabel.setText(operation + answer);
            resultLabel.repaint();
            break; // use break as it the process will continue. your case would be useless then.
        case "-":
            answer = x - y;
            resultLabel.setText(operation + answer);
            resultLabel.repaint();
            break;
        case "*":
            answer = x * y; // you dont need to spam switch condition. 
                            // if you are checking for one condition, use IF
            if (y == 0) {
                resultLabel.setText("Cannot divide by 0");
            }
            resultLabel.setText(operation + answer);
            resultLabel.repaint();
            break;
        case "/":
            answer = x / y;
            resultLabel.setText(operation + answer);
            resultLabel.repaint();
            break;
        case "%":
            answer = x % y;
            resultLabel.setText(operation + answer);
            resultLabel.repaint();
            break;
        default:
            resultLabel.setText("Illegal operator");
            break;
        }
    }
}

あなたの質問に答えるために、どのように出力を表示します。あなたはそれがcatchブロックに落ちたときのactionPerformedメソッドに戻り値を使用する必要があります。あなたは、プロセスを終了させる必要があるため。

これを見てみてください。エラーが表示されたら、あなたはresultLabelにテキストを設定します。「オペランドが整数ではない」と述べました。

そして、計算が進むと、あなたはresultLabelで再びテキストを設定します。resultLabelの値は何でしょうか？

乾杯！