ThreadLocal

先上两个BUG

BUG 1:

package ThreadLocal;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @Author: 赵博雅
 * @Date: 2020/4/24 15:49
 *
 * String类型转Date类型（format）
 */
public class SimpleDateFormatBugTest {

    private static SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    private static Date parse(String date){
        try {
            return sdf.parse(date);
        }catch (ParseException e){
            e.printStackTrace();
        }
        return null;
    }

    public static void main(String[] args) {
        Thread thread1 = new Thread(() -> {
            Date parse = parse("2020-04-24 15:54:59");
            System.out.println("第一次执行时间：" + parse);
        });

        Thread thread2 = new Thread(() -> {
            Date parse = parse("2020-04-25 15:54:59");
            System.out.println("第二次执行时间：" + parse);
        });

        Thread thread3 = new Thread(() -> {
            Date parse = parse("2020-04-26 15:54:59");
            System.out.println("第三次执行时间：" + parse);
        });

        thread1.start();
        thread2.start();
        thread3.start();

        try {
            thread1.join();
            thread2.join();
            thread3.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("线程退出");
    }

}

多线程下使用同一个SimpleDateFormat实例将String日期格式转换成Date只能获取到其中一次的结果，其他两个线程出错

BUG 2:

package ThreadLocal;

import java.text.ParseException;
import java.util.Date;

/**
 * @Author: 赵博雅
 * @Date: 2020/4/24 16:04
 * <p>
 * Date日期转String类型（format）
 */
public class SimpleDateFormat {

    private static java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    private static Date d1 = null;
    private static Date d2 = null;
    private static Date d3 = null;

    static {
        try {
            d1 = sdf.parse("2020-04-24 15:54:59");
            d2 = sdf.parse("2020-04-25 15:54:59");
            d3 = sdf.parse("2020-04-26 15:54:59");
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        Thread thread1 = new Thread(() -> {
            String format = sdf.format(d1);
            System.out.println("第一次执行时间：" + format);
        });

        Thread thread2 = new Thread(() -> {
            String format = sdf.format(d2);
            System.out.println("第二次执行时间：" + format);
        });

        Thread thread3 = new Thread(() -> {
            String format = sdf.format(d3);
            System.out.println("第三次执行时间：" + format);
        });
        
        thread1.start();
        thread2.start();
        thread3.start();
        
        System.out.println("线程退出");
    }
}