cn.hutool.core.comparator

Class NullComparator<T>

java.lang.Object

cn.hutool.core.comparator.NullComparator<T>

Type Parameters:

T - 被比较的对象

All Implemented Interfaces:

Serializable, Comparator<T>

Direct Known Subclasses:

FieldsComparator, FuncComparator

public class NullComparator<T>
extends Object
implements Comparator<T>, Serializable

null友好的比较器包装，如果nullGreater，则null > non-null，否则反之。
如果二者皆为null，则为相等，返回0。
如果二者都非null，则使用传入的比较器排序。
传入比较器为null，则看被比较的两个对象是否都实现了Comparable实现则调用Comparable.compareTo(Object)。 如果两者至少一个未实现，则视为所有元素相等。

Since:

5.7.10

Author:

looly

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Comparator<T>	comparator
protected boolean	nullGreater

Constructor Summary

Constructors

Constructor and Description
NullComparator(boolean nullGreater, Comparator<? super T> comparator) 构造

Method Summary

Modifier and Type	Method and Description
int	compare(T a, T b)
protected int	doCompare(T a, T b) 不检查null的比较方法 用户可自行重写此方法自定义比较方式
Comparator<T>	thenComparing(Comparator<? super T> other)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, equals, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Detail

nullGreater

protected final boolean nullGreater

comparator

protected final Comparator<T> comparator

Constructor Detail

NullComparator

public NullComparator(boolean nullGreater,
                      Comparator<? super T> comparator)

构造

Parameters:

nullGreater - 是否null最大，排在最后

comparator - 实际比较器

Method Detail

compare

public int compare(T a,
                   T b)

Specified by:

compare in interface Comparator<T>

thenComparing

public Comparator<T> thenComparing(Comparator<? super T> other)

Specified by:

thenComparing in interface Comparator<T>

doCompare

protected int doCompare(T a,
                        T b)

不检查null的比较方法
用户可自行重写此方法自定义比较方式

Parameters:

a - A值

b - B值

Returns:

比较结果，-1:a小于b，0:相等，1:a大于b