Java/W9/service/HistoryManager.java

package com.example.datacollect.service;
import java.security.PublicKey;
import java.util.ArrayList;
import java.util.List;
public class HistoryManager implements HistoryService{
    private final List<String> history=new ArrayList<>();
    private static final int MAX_SIZE=100;
    @Override
    public void add(String command){
        if (command == null || command.trim().isEmpty()) {
            return;
        }
        history.add(command.trim());
        if (history.size() > MAX_SIZE) {
            history.remove(0);
        }
    }
    @Override
    public List<String> getHistory() {
        return new ArrayList<>(history);
    }
    @Override
    public void clear() {
        history.clear();
    }
    @Override
    public String get(int index) {
        if (index >= 0 && index < history.size()) {
            return history.get(index);
        }
        return null;
    }
}