Java/W9/command/ListCommand.java

package com.example.datacollect.command;

import com.example.datacollect.model.Article;
import com.example.datacollect.model.DataService;
import com.example.datacollect.view.ConsoleView;
import java.util.List;

public class ListCommand implements Command {
    private final ConsoleView view;
    private static final  int DEFAULT_LIMIT=20;
    public ListCommand(ConsoleView view) {
        this.view = view;
    }

    @Override
    public String getName() {
        return "list";
    }

    @Override
    public void execute(String[] args,DataService dataService) {
        // 1. 解析参数：list <limit>
        int limit = DEFAULT_LIMIT;
        if (args.length > 1) {
            try {
                limit = Integer.parseInt(args[1]);
                if (limit < 1) {
                    view.printError("数量必须大于 0");
                    return;
                }
            } catch (NumberFormatException e) {
                view.printError("参数必须是数字");
                return;
            }
        }
        // 2. 获取数据
        List<Article> allArticles = dataService.getAllArticles();
        int totalSize = allArticles.size();
        // 3. 处理分页/截取
        List<Article> displayList;
        if (totalSize <= limit) {
            displayList = allArticles;
        } else {
            displayList = allArticles.subList(0, limit);
        }
        // 4. 调用视图显示（传递总数以便显示分页信息）
        view.display(displayList, totalSize);
    }

}