java/w9/HistoryCommand.java

import java.util.ArrayList;
import java.util.List;

public class HistoryCommand {
    private final List<String> commandHistory = new ArrayList<>();

    public void recordCommand(String command) {
        if (command != null && !command.isBlank()) {
            commandHistory.add(command.trim());
        }
    }

    public List<String> getHistory() {
        return new ArrayList<>(commandHistory);
    }

    public void printHistory() {
        System.out.println("=== 命令历史 ===");
        for (int i = 0; i < commandHistory.size(); i++) {
            System.out.printf("%d: %s%n", i + 1, commandHistory.get(i));
        }
    }

    public void clearHistory() {
        commandHistory.clear();
    }

    public static void main(String[] args) {
        HistoryCommand history = new HistoryCommand();
        history.recordCommand("crawl `https://example.com` ");
        history.recordCommand("list");
        history.recordCommand("exit");

        history.printHistory();
    }
}