SimpleDateFormat 非线程安全，不能并发使用 



import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.atomic.AtomicLong;

public class SimpleDateFormatTest {
    static final String FORMAT = "yyyy-MM-dd HH:mm:ss";
    static final SimpleDateFormat sdf = new SimpleDateFormat(FORMAT);
    static final int TASK_COUNT = 3;
    final static AtomicLong formatError = new AtomicLong(0);
    final static AtomicLong parseError = new AtomicLong(0);
    final static AtomicLong success = new AtomicLong(0);

    static volatile String formatErrorInfo = null;
    static volatile String parseErrorInfo = null;

    public static void main(String[] args) throws Exception {
        for (int i = 0; i < TASK_COUNT; i++) {
            Thread task = new FormatAndParseTask();
            task.start();
        }

        while (true) {
            Thread.sleep(3000);
            System.out.println(success + " " + formatError + " " + parseError);
            System.out.println(formatErrorInfo);
            System.out.println(parseErrorInfo);
            System.out.println();
        }

    }

    private static class FormatAndParseTask extends Thread {
        public void run() {
            while (true) {
                Date time1 = new Date();
                String str = null;
                try {
                    str = sdf.format(time1);
                } catch (Throwable e) {
                    formatError.incrementAndGet();
                    formatErrorInfo = "formatError:" + e;
                    // System.out.println("format error,"+e);
                    continue;
                }
                Date time2 = null;
                try {
                    time2 = sdf.parse(str);
                } catch (Throwable e) {
                    parseError.incrementAndGet();
                    parseErrorInfo = "parseError:" + e;
                    // System.out.println("parse error,"+e);
                    continue;
                }
                success.incrementAndGet();
            }
        }
    }
}




601627 79 42592
formatError:java.lang.ArrayIndexOutOfBoundsException
parseError:java.lang.NumberFormatException: For input string: ""

1606037 216 126336
formatError:java.lang.ArrayIndexOutOfBoundsException
parseError:java.lang.NumberFormatException: For input string: ""

2552992 399 211061
formatError:java.lang.ArrayIndexOutOfBoundsException
parseError:java.lang.NumberFormatException: For input string: ".2001E32001"

2557761 7496216 211440
formatError:java.lang.ArrayIndexOutOfBoundsException
parseError:java.lang.NumberFormatException: For input string: ""

2557761 14828661 211440
formatError:java.lang.ArrayIndexOutOfBoundsException
parseError:java.lang.NumberFormatException: For input string: ""

2557761 22464674 211440
formatError:java.lang.ArrayIndexOutOfBoundsException
parseError:java.lang.NumberFormatException: For input string: ""


完整代码
https://gitee.com/dyyx/hellocode/blob/master/src/dyyx/conc/SimpleDateFormatTest.java