在 Java 中洗牌无序集合的元素
原文:https://www . geeksforgeeks . org/shuffling-元素无序-java 中的集合/
java 中的无序集合不提供任何顺序，即元素不能使用特定的索引或排序来访问，就像我们在有序集合(如 List )的情况下所做的那样。集和地图是无序收集的例子。
在 java 中，我们不能直接使用collections . shuffle()方法来打乱无序的集合，因为它需要一个列表作为参数。****
**用于混洗元素，****
- *我们必须首先将无序集合的元素存储在一个列表中，然后我们可以使用 *Collections.shuffle() 方法对其进行洗牌。****
**1)混洗集合中的元素****
*Java 语言(一种计算机语言，尤用于创建网站)*
**// Java program to demonstrate the shuffling
// of a set
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Creating a Hashset
Set<Integer> st = new HashSet<>();
// Inserting elements to the set
st.add(91);
st.add(0);
st.add(55);
st.add(10);
st.add(9);
// 9 won't be inserted to the Set as Hashset does
// not take duplicate entries
st.add(9);
// Displaying the elements of the set
System.out.print("The Set before shuffling: ");
for (int i : st)
System.out.print(i + " ");
System.out.println();
// Creating a List and storing the values of the
// Set inside it by passing the Set as a parameter
// to the constructor
List<Integer> list = new ArrayList<>(st);
// Shuffling the elements of the list using using
// Collections.shuffle() method
Collections.shuffle(list);
// Displaying the elements of the list
System.out.print("The List (containing elements of the Set) after shuffling: ");
for (int i : list)
System.out.print(i + " ");
}
}**
**Output
The Set before shuffling: 0 55 9 10 91
The List (containing elements of the Set) after shuffling: 55 0 91 10 9
```****
******2)洗牌地图的元素******
## ****Java 语言(一种计算机语言，尤用于创建网站)****
```java
**// Java program to demonstrate the shuffling
// of a map
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Creating a HashMap
Map<Integer, String> mp
= new HashMap<Integer, String>();
// Inserting some values inside the HashMap
mp.put(1, "Geeks");
mp.put(2, "for");
mp.put(3, "Geeks");
mp.put(4, "is");
mp.put(5, "love");
// Displaying the map
System.out.println("The Map before shuffling: ");
for (Map.Entry<Integer, String> entry :mp.entrySet())
System.out.println(entry.getKey() + " "
+ entry.getValue());
System.out.println();
// Creating a list and storing the elements of the
// Map inside of it
List<Map.Entry<Integer, String> > list
= new ArrayList<>(mp.entrySet());
// Shuffling the list using shuffle() method
Collections.shuffle(list);
// Displaying the list
System.out.println("The List (containing the elements of the Map)"
+ " After shuffing: ");
for (Map.Entry<Integer, String> entry : list)
System.out.println(entry.getKey() + " "
+ entry.getValue());
System.out.println();
}
}**
**Output
```java The Map before shuffling: 1 Geeks 2 for 3 Geeks 4 is 5 love
The List (containing the elements of the Map) After shuffing: 2 for 5 love 4 is 3 Geeks 1 Geeks ```****
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