课题打卡~请老师检查

package com.imooc.thread;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ThreadLocalStringBuilder {

    private static ExecutorService executorService = Executors.newFixedThreadPool(10);

    public String data(int num) {
        StringBuilder stringBuilder = ThreadSafeStringBuilder.stringBuilderThreadLocal.get();
        stringBuilder.setLength(0);
        stringBuilder.append("数字"+num);
        return stringBuilder.toString();
    }

    public static void main(String[] args) {
        StringBuilder val = new StringBuilder();
        for (int i = 1; i <= 20; i++) {
            int finalI = i;
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(1);
                        String data = new ThreadLocalStringBuilder().data(finalI);
                        System.out.println(data);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            });
        }
        executorService.shutdown();
    }
}