Javaコードを実行する

JavaLauncher.java

import module java.desktop;

void main() {
    var f = new JFrame("Javaランチャー");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setSize(800, 600);
    f.setLocationRelativeTo(null);
    
    var split = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
    var taSource = new JTextArea();
    taSource.setLineWrap(false);
    taSource.setFont(new Font(Font.MONOSPACED, Font.PLAIN, 12));
    split.add(JSplitPane.TOP, new JScrollPane(taSource, 
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED));
    var taLog = new JTextArea();
    taSource.setLineWrap(true);
    split.add(JSplitPane.BOTTOM, new JScrollPane(taLog, 
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER));
    f.add(split);

    var stopButton = new JButton("停止");
    stopButton.setEnabled(false);

    var button = new JButton("起動");
    button.addActionListener(_ -> {
        taLog.setText("");
        button.setEnabled(false);
        stopButton.setEnabled(true);
        Thread.ofPlatform().start(() -> {
            launch(taSource.getText(), taLog, stopButton);
            SwingUtilities.invokeLater(() -> {
                button.setEnabled(true);
                stopButton.setEnabled(false);
            });
        });
    });

    stopButton.addActionListener(_ -> stopProcess());

    var paste = new JButton("貼り付け");
    paste.addActionListener(_ -> pasteFromClipboard(taSource));

    var clip = new JButton("ログコピー");
    clip.addActionListener(_ -> copyToClipboard(taLog.getText()));
    
    var p = new JPanel(new FlowLayout(FlowLayout.RIGHT));
    p.add(paste);
    p.add(button);
    p.add(stopButton);
    p.add(clip);

    f.add(BorderLayout.SOUTH, p);

    Runtime.getRuntime().addShutdownHook(Thread.ofPlatform().unstarted(() -> {
        if (currentProcess != null && currentProcess.isAlive()) {
            currentProcess.destroyForcibly();
        }
    }));
    
    f.setVisible(true);
    split.setDividerLocation(split.getHeight() * 2 / 3);
}

void pasteFromClipboard(JTextArea target) {
    try {
        var contents = Toolkit.getDefaultToolkit()
                .getSystemClipboard()
                .getContents(null);
        if (contents != null && contents.isDataFlavorSupported(DataFlavor.stringFlavor)) {
            String text = (String) contents.getTransferData(DataFlavor.stringFlavor);
            target.setText(text);
        }
    } catch (Exception ex) {
        System.out.println(ex);
    }
}

void copyToClipboard(String log) {
    StringSelection sel = new StringSelection(log);
    Toolkit.getDefaultToolkit()
           .getSystemClipboard()
           .setContents(sel, null);
}

final String JAVA_COMMAND = "C:\\Users\\naoki\\java\\jdk\\jdk-25\\bin\\java.exe";

Process currentProcess = null;

void stopProcess() {
    if (currentProcess != null && currentProcess.isAlive()) {
        currentProcess.destroy();
    }
}

void launch(String source, JTextArea logArea, JButton stopButton) {
    Path tempFile = null;
    Path tempDir = null;
    try {
        tempDir = Files.createTempDirectory("compileTmp");
        tempFile = tempDir.resolve("main.java");

        Files.writeString(tempFile, source, StandardOpenOption.CREATE);

        currentProcess = new ProcessBuilder(JAVA_COMMAND, tempFile.toString())
                .redirectErrorStream(true)
                .start();

        try (BufferedReader br =
                new BufferedReader(new InputStreamReader(currentProcess.getInputStream(), StandardCharsets.UTF_8))) {
            String line;
            boolean first = true;
            while ((line = br.readLine()) != null) {
                if (first && line.startsWith("Picked up")) { first = false; continue; }
                String l = line.replace(tempDir.toString() + File.separator, "");
                SwingUtilities.invokeLater(() -> logArea.append(l + "\n"));
            }
        }

        currentProcess.waitFor();
        if (currentProcess.exitValue() == 0) {
            SwingUtilities.invokeLater(() -> logArea.append("no error\n"));
        }
    } catch (InterruptedException ex) {
        SwingUtilities.invokeLater(() -> logArea.append("プロセスが停止されました\n"));
    } catch (Exception ex) {
        System.out.println(ex);
    } finally {
        currentProcess = null;
        if (tempFile != null) {
            try { Files.deleteIfExists(tempFile); } catch (IOException _) {}
        }
        if (tempDir != null) {
            try { Files.deleteIfExists(tempDir); } catch (IOException _) {}
        }
    }
}