泛型的理解

 

 

 

 

 

 

 

 

 

 

@Slf4j
public class TimeTest {
    private final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    /**
     * @Description:  修改特定的时间
     * @param:
     * @date: 2020/1/16 22:02
     */
    @Test
    public void test01(){
        Date date = new Date();
        try {
            date = sdf.parse("1970-11-9 6:32:25");
        } catch (ParseException e) {
            log.info("转换失败:{}",e.getMessage());
        }
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        BigDecimal bigDecimal = new BigDecimal(1.55);
        int i = 90;
        float j =9.89F;
        double k = 0.23D;
        byte l=4;
        transDateByDate(calendar.getTime(),bigDecimal);
        System.out.println("**********1********");
        transDateByDate(calendar.getTime(),i);
        System.out.println("**********2********");
        transDateByDate(calendar.getTime(),j);
        System.out.println("***********3*******");
        transDateByDate(calendar.getTime(),k);
        System.out.println("***********4*******");
        transDateByDate(calendar.getTime(),l);
    }

    privateextends Number> void transDateByDate(Date date, T data) {
        double v = data.doubleValue();
        String s = String.valueOf(v).toString();
        System.out.println(s);
        String[] split = s.split("\\.");
        System.out.println(split.length);
        if (split.length>1){
            String s1 = split[0];
            System.out.println(s1);
            String s2 = split[1];
            System.out.println(s2);
            s2="0."+s2;
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(date);
            System.out.println(sdf.format(calendar.getTime()).trim()); 
            calendar.add(Calendar.YEAR,-Integer.valueOf(s1));

            System.out.println(Math.floor(Double.valueOf(s2)*12));
            calendar.add(Calendar.MONTH,-Integer.valueOf((int) Math.floor(Double.valueOf(s2)*12)));
            Date newTime = calendar.getTime();
            String stringDate = sdf.format(newTime).trim();
            System.out.println(stringDate);  
        }
    }
}

结果:

1.55
2
1
55
1970-11-09 06:32:25
6.0
1969-05-09 06:32:25
**********1********
90.0
2
90
0
1970-11-09 06:32:25
0.0
1880-11-09 06:32:25
**********2********
9.890000343322754
2
9
890000343322754
1970-11-09 06:32:25
10.0
1961-01-09 06:32:25
***********3*******
0.23
2
0
23
1970-11-09 06:32:25
2.0
1970-09-09 06:32:25
***********4*******
4.0
2
4
0
1970-11-09 06:32:25
0.0
1966-11-09 06:32:25