前面我们讲过Java提供了一个用于比较的股票量化交易软件,接口Comparable,提供了一个比较的方法,所有实现该股票量化交易软件,接口的类,都动态的实现了该比较方法。实际上Java中除了比较一个股票量化交易软件,接口外，还提供了一个股票量化交易软件,接口，该股票量化交易软件,接口也是具有比较的功能，但该股票量化交易软件,接口注重的却是比较容器，然后对其排序，这就是Comparator，下面我们就来具体认识一下；
首先看一下源码：
package java.util;
import java.io.Serializable;
import java.util.function.Function;
import java.util.function.ToIntFunction;
import java.util.function.ToLongFunction;
import java.util.function.ToDoubleFunction;
import java.util.Comparators;
@FunctionalInterface
public interface Comparator {
int compare(T o1, T o2);
boolean equals(Object obj);
default Comparator reversed() {
return Collections.reverseOrder(this);
}
default Comparator thenComparing(Comparator other) {
Objects.requireNonNull(other);
return (Comparator & Serializable) (c1, c2) -> {
int res = compare(c1, c2);
return (res != 0) ? res : other.compare(c1, c2);
};
}
default Comparator thenComparing(
Function keyExtractor,
Comparator keyComparator)
{
return thenComparing(comparing(keyExtractor, keyComparator));
}
default > Comparator thenComparing(
Function keyExtractor)
{
return thenComparing(comparing(keyExtractor));
}
default Comparator thenComparingInt(ToIntFunction keyExtractor) {
return thenComparing(comparingInt(keyExtractor));
}
default Comparator thenComparingLong(ToLongFunction keyExtractor) {
return thenComparing(comparingLong(keyExtractor));
}
default Comparator thenComparingDouble(ToDoubleFunction keyExtractor) {
return thenComparing(comparingDouble(keyExtractor));
}
public static > Comparator reverseOrder() {
return Collections.reverseOrder();
}
@SuppressWarnings('unchecked')
public static > Comparator naturalOrder() {
return (Comparator) Comparators.NaturalOrderComparator.INSTANCE;
}
public static Comparator nullsFirst(Comparator comparator) {
return new Comparators.NullComparator<>(true, comparator);
}
public static Comparator nullsLast(Comparator comparator) {
return new Comparators.NullComparator<>(false, comparator);
}
public static Comparator comparing(
Function keyExtractor,
Comparator keyComparator)
{
Objects.requireNonNull(keyExtractor);
Objects.requireNonNull(keyComparator);
return (Comparator & Serializable)
(c1, c2) -> keyComparator.compare(keyExtractor.apply(c1),
keyExtractor.apply(c2));
}
public static > Comparator comparing(
Function keyExtractor)
{
Objects.requireNonNull(keyExtractor);
return (Comparator & Serializable)
(c1, c2) -> keyExtractor.apply(c1).compareTo(keyExtractor.apply(c2));
}
public static Comparator comparingInt(ToIntFunction keyExtractor) {
Objects.requireNonNull(keyExtractor);
return (Comparator & Serializable)
(c1, c2) -> Integer.compare(keyExtractor.applyAsInt(c1), keyExtractor.applyAsInt(c2));
}
public static Comparator comparingLong(ToLongFunction keyExtractor) {
Objects.requireNonNull(keyExtractor);
return (Comparator & Serializable)
(c1, c2) -> Long.compare(keyExtractor.applyAsLong(c1), keyExtractor.applyAsLong(c2));
}
public static Comparator comparingDouble(ToDoubleFunction keyExtractor) {
Objects.requireNonNull(keyExtractor);
return (Comparator & Serializable)
(c1, c2) -> Double.compare(keyExtractor.applyAsDouble(c1), keyExtractor.applyAsDouble(c2));
}
}
我们设计类的时候，可能没有考虑到让类实现Comparable股票量化交易软件,接口，那么就需要用到另外的一个比较器股票量化交易软件,接口Comparator。
从之前的实例我们可以发现，compareTo(To)只有一个参数，而Comparator股票量化交易软件,接口中必须要实现的compare(To1,To就有两个参数。
例如：
class StudentComparator implements Comparator{
@Override
public int compare(Student o1, Student o2) {
// TODO Auto-generated method stub
if(o1.getScore()>o2.getScore())
return -1;
else if(o1.getScore()o2.getAge())
return 1;
else if(o1.getAge()上面依然是对student对象数组进行排序，用的都是Array.sort方法，不同的是实现comparator股票量化交易软件,接口时，sort方法需要传进来两个参数，即stu对象数组，以及重写的实现了comparator比较方法类。
我们这里只是简单了解了Comparator的方法
文章为作者独立观点，不代表 股票程序化软件自动交易接口观点
股民评论