cn.hutool.core.builder.IDKey Maven / Gradle / Ivy
package cn.hutool.core.builder;
import java.io.Serializable;
/**
* 包装唯一键（System.identityHashCode()）使对象只有和自己 equals
*
* 此对象用于消除小概率下System.identityHashCode()产生的ID重复问题。
*
* 来自于Apache-Commons-Lang3
* @author looly，Apache-Commons
* @since 4.2.2
*/
final class IDKey implements Serializable{
private static final long serialVersionUID = 1L;
private final Object value;
private final int id;
/**
* 构造
*
* @param obj 计算唯一ID的对象
*/
public IDKey(final Object obj) {
id = System.identityHashCode(obj);
// There have been some cases (LANG-459) that return the
// same identity hash code for different objects. So
// the value is also added to disambiguate these cases.
value = obj;
}
/**
* returns hashcode - i.e. the system identity hashcode.
*
* @return the hashcode
*/
@Override
public int hashCode() {
return id;
}
/**
* checks if instances are equal
*
* @param other The other object to compare to
* @return if the instances are for the same object
*/
@Override
public boolean equals(final Object other) {
if (!(other instanceof IDKey)) {
return false;
}
final IDKey idKey = (IDKey) other;
if (id != idKey.id) {
return false;
}
// Note that identity equals is used.
return value == idKey.value;
}
}