Java AbstractMap.SimpleEntry hashCode()用法及代碼示例

AbstractMap.SimpleEntry <K，V>用於維護鍵和值條目。可以使用setValue方法更改該值。此類有助於構建自定義Map實現。

AbstractMap.SimpleEntry <K，V>的hashCode()方法返回此Map條目的哈希碼值。映射條目e的哈希碼可以通過以下方式計算：

(e.getKey()==null   ? 0:e.getKey().hashCode()) ^
   (e.getValue()==null ? 0:e.getValue().hashCode())

用法:

public int hashCode()

參數：此方法不接受任何內容。

返回值：此方法返回此映射條目的哈希碼值。

以下示例程序旨在說明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); 
        } 
    } 
}

輸出：

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); 
        } 
    } 
}

輸出：

hashCode = -873386249
hashCode = -874293612
hashCode = -910934441
hashCode = -910552137
hashCode = -910906733

參考文獻： https://docs.oracle.com/javase/10/docs/api/java/util/AbstractMap.SimpleEntry.html#hashCode()

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注：本文由純淨天空篩選整理自AmanSingh2210大神的英文原創作品 AbstractMap.SimpleEntry hashCode() Method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。