Java 中的 Collections.nCopies()
Collections.nCopies() 的作用是返回一个包含给定对象的 n 个副本的不可变列表。如果我们想用给定对象的 n 个副本创建一个列表，这个函数会有所帮助。新分配的数据对象很小，即它包含对数据对象的单一引用。
语法:
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:如果号的值小于 0，该函数将抛出 IllegalArgumentException 。
例:
Java 语言(一种计算机语言，尤用于创建网站)
// 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");
}
}
Output :
The list returned is :
GeeksforGeeks GeeksforGeeks GeeksforGeeks GeeksforGeeks
The list returned is :
GeeksQuiz GeeksQuiz GeeksQuiz
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