jdk1.8 java.util.Date 的equals的坑

原文链接： https://my.oschina.net/sglz1993/blog/1922301

一句话：java的Date比较请不要用equals方法。

背景说明：某对象有一个java.util.Date的属性，但是从数据库查封装的对象是java.sql.Timestamp，原因很简单，直接看源码

java.util.Date：

public boolean equals(Object obj) { return obj instanceof Date && getTime() == ((Date) obj).getTime(); }

public int compareTo(Date anotherDate) { long thisTime = getMillisOf(this); long anotherTime = getMillisOf(anotherDate); return (thisTime

java.sql.Timestamp extends  java.util.Date

public boolean equals(java.lang.Object ts) { if (ts instanceof Timestamp) { return this.equals((Timestamp)ts); } else { return false; } }

public int compareTo(java.util.Date o) { if(o instanceof Timestamp) { // When Timestamp instance compare it with a Timestamp // Hence it is basically calling this.compareTo((Timestamp))o); // Note typecasting is safe because o is instance of Timestamp return compareTo((Timestamp)o); } else { // When Date doing a o.compareTo(this) // will give wrong results. Timestamp ts = new Timestamp(o.getTime()); return this.compareTo(ts); } }

        java.sql.Timestamp 的equals 只能比较java.sql.Timestamp对象，但compareTo对java.util.Date进行了适配，或者直接用getTime进行比较也是一样

转载于:https://my.oschina.net/sglz1993/blog/1922301