java/w9/HistoryCommand.java

package Article;

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

public class HistoryCommand {
    private List<String> commandHistory;

    public HistoryCommand() {
        this.commandHistory = new ArrayList<>();
    }

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

    public List<String> getAllCommands() {
        return new ArrayList<>(commandHistory); // 返回副本，保护内部数据
    }

    public String getLastCommand() {
        return commandHistory.isEmpty() ? null : commandHistory.get(commandHistory.size() - 1);
    }

    public void printHistory() {
        for (int i = 0; i < commandHistory.size(); i++) {
            System.out.println((i + 1) + ". " + commandHistory.get(i));
        }
    }

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

    public int size() {
        return commandHistory.size();
    }
}