【JAVA】SimpleDataFormat

【摘要】 问题现象
写了一个例子测试-SimpleDataFormat
看下面的实验： 
package com.programing.unsafe; import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Date; public class SimpleDateFor…

问题现象

写了一个例子测试-SimpleDataFormat

看下面的实验：

      package com.programing.unsafe;

      import java.text.ParseException;

      import java.text.SimpleDateFormat;

      import java.util.Date;

      public class SimpleDateFormatThread extends Thread {

      private SimpleDateFormat sdf;

      private String dateString;

      public SimpleDateFormatThread(SimpleDateFormat sdf, String dateString) {

      this.sdf = sdf;

      this.dateString = dateString;

       }

      @Override

      public void run() {

      //测试传入日期和转换日期是否一致

      try {

      //sdf = new SimpleDateFormat("yyyy-MM-dd"); //创建线程自己的SimpleDateFormat 才能解决这个问题

       Date dateRef = sdf.parse(dateString);   //使用公共的SimpleDateFormat 线程不安全

       String newDateString = sdf.format(dateRef).toString();

      if (!newDateString.equals(dateString)) {

       System.out.println(Thread.currentThread().getName() + " 报错：" + dateString + " =>" + newDateString);

       }else{

       System.out.println(Thread.currentThread().getName() + " 正确：" + dateString + " =>" + newDateString);

       }

       } catch (ParseException e) {

       e.printStackTrace();

       }

       }

      }

      package com.programing.unsafe;

      import java.text.SimpleDateFormat;

      public class SimpleDateFormatTest {

      public static void main(String[] args) {

      //从结果中可以查看到SimplateDateFormat类再多线程环境中处理日期很容易出现转换错误

       SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

       String[] dateStrings = new String[]{"2018-01-01", "2018-01-02", "2018-01-03", "2018-01-04", "2018-01-05", "2018-01-06", "2018-01-07", "2018-01-08", "2018-01-09"};

      for (int i = 0; i < dateStrings.length; i++) {

       SimpleDateFormatThread thread = new SimpleDateFormatThread(sdf, dateStrings[i]);

       thread.start();

       }

       }

      }

  


                    
        
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