Java Collections.nCopies()用法及代码示例

Collections.nCopies()的作用是返回一个不可变的列表，其中包含给定对象的n个副本。如果我们要创建具有给定对象的n个副本的列表，则此函数很有帮助。新分配的数据对象很小，即它包含对数据对象的单个引用。

用法:

public static <T> List<T> nCopies(int number, T object)

where, number is the number of copies
of object and object represents the 
element which will appear number times
in the returned list. T represents generic type.

异常：如果number的值小于0，则该函数引发IllegalArgumentException。

例：

Java

// Java code to show implementation 
// of Collections.nCopies() 
import java.util.*; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // creating a list where first argument 
        // represents the number of copies and 
        // the second argument represents the 
        // element to be copied for 'number' times 
        // This will create 4 copies of the objects. 
        List list = Collections.nCopies(4, "GeeksforGeeks"); 
  
        // Displaying the list returned 
        System.out.println("The list returned is :"); 
        Iterator itr = list.iterator(); 
        while (itr.hasNext()) { 
            System.out.print(itr.next() + " "); 
        } 
        System.out.println("\n"); 
  
        List list1 = Collections.nCopies(3, "GeeksQuiz"); 
      
        // Displaying the list returned 
        System.out.println("The list returned is :"); 
        Iterator itr1 = list1.iterator();   
        while (itr1.hasNext()) { 
            System.out.print(itr1.next() + " "); 
        } 
        System.out.print("\n"); 
    } 
}

输出：

The list returned is :
GeeksforGeeks GeeksforGeeks GeeksforGeeks GeeksforGeeks 

The list returned is :
GeeksQuiz GeeksQuiz GeeksQuiz

相关用法

注：本文由纯净天空筛选整理自Sahil_Bansall大神的英文原创作品 Collections.nCopies() in Java。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。