AbstractMap.SimpleEntry <K,V>用于维护键和值条目。可以使用setValue方法更改该值。此类有助于构建自定义Map实现。
AbstractMap.SimpleEntry <K,V>的hashCode()方法返回此Map条目的哈希码值。映射条目e的哈希码可以通过以下方式计算:
(e.getKey()==null ? 0:e.getKey().hashCode()) ^ (e.getValue()==null ? 0:e.getValue().hashCode())
用法:
public int hashCode()
参数:此方法不接受任何内容。
返回值:此方法返回此映射条目的哈希码值。
以下示例程序旨在说明hashCode()方法:
程序1:
// Java program to demonstrate
// AbstractMap.SimpleEntry.hashCode() method
import java.util.*;
import java.util.AbstractMap.SimpleEntry;
public class GFG {
@SuppressWarnings({ "unchecked", "rawtypes" })
public static void main(String[] args)
{
// create a ArrayList of Map
ArrayList<AbstractMap
.SimpleEntry<Integer, Integer> >
arrayList
= new ArrayList<AbstractMap
.SimpleEntry<Integer, Integer> >();
// add values
arrayList.add(new AbstractMap.SimpleEntry(0, 123));
arrayList.add(new AbstractMap.SimpleEntry(1, 130));
arrayList.add(new AbstractMap.SimpleEntry(2, 994));
// print keys
for (int i = 0; i < arrayList.size(); i++) {
// get map from list
AbstractMap.SimpleEntry<Integer, Integer>
map
= arrayList.get(i);
// get value from map using hashCode()
int value = map.hashCode();
System.out.println("HashCode = " + value);
}
}
}
输出:
HashCode = 123 HashCode = 131 HashCode = 992
程序2:
// Java program to demonstrate
// AbstractMap.SimpleEntry.hashCode() method
import java.util.*;
public class GFG {
@SuppressWarnings({ "unchecked", "rawtypes" })
public static void main(String[] args)
{
// create a ArrayList of Map
ArrayList<AbstractMap
.SimpleEntry<String, String> >
arrayList
= new ArrayList<AbstractMap
.SimpleEntry<String, String> >();
// add values
arrayList.add(new AbstractMap
.SimpleEntry(" 001AB ", " Emp 1"));
arrayList.add(new AbstractMap
.SimpleEntry(" 011AC ", " Emp 2"));
arrayList.add(new AbstractMap
.SimpleEntry(" 111AD ", " Emp 3"));
arrayList.add(new AbstractMap
.SimpleEntry(" 101BE ", " Emp 4"));
arrayList.add(new AbstractMap
.SimpleEntry(" 110CE ", " Emp 5"));
// print keys
for (int i = 0; i < arrayList.size(); i++) {
// get map from list
AbstractMap.SimpleEntry<String, String>
map
= arrayList.get(i);
// get hashcode value from map using hashCode()
int value = map.hashCode();
System.out.println("hashCode = " + value);
}
}
}
输出:
hashCode = -873386249 hashCode = -874293612 hashCode = -910934441 hashCode = -910552137 hashCode = -910906733
参考文献: https://docs.oracle.com/javase/10/docs/api/java/util/AbstractMap.SimpleEntry.html#hashCode()
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注:本文由纯净天空筛选整理自AmanSingh2210大神的英文原创作品 AbstractMap.SimpleEntry hashCode() Method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。