用了ThreadLocal还是有重复值

相关代码：

package thread_learn;

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

public class ThreadStringBuilder {
    public static ExecutorService executorService = Executors.newFixedThreadPool(10);
    public static void main(String[] args) {
        for (int i = 0; i < 20; i++) {
            int fianl = i;
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(10);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(ThreadSafeStringBuilder.getString(fianl));
                }
            });
        }
    }
}

相关代码：

​package thread_learn;

public class ThreadSafeStringBuilder {
    public static ThreadLocal<StringBuilder> stringBuilderThreadLocal = ThreadLocal.withInitial(() -> new StringBuilder());


    public static String getString(int number) {
        StringBuilder stringBuilder = ThreadSafeStringBuilder.stringBuilderThreadLocal.get();
        stringBuilder.append("数字" + number+" ");
        stringBuilder.append(Thread.currentThread().getName());
        return stringBuilder.toString();
    }

}