java.util.Vector.clear() java.util.Vector.capacity() java.util.Vector.clone() 描述 clear()方法被用来去除所有从此向量元素。除非它抛出异常,否则在此调用之后Vector将为空。 声明 以下是java.util.Vector.clear()方法的声明 public void clear() 参数 此方法不接受任何参数作为输入。 返回值 返回类型为void,因此它不返回任何值。 异常 UnsupportedOperationException - 如果Collection不支持clear方法,则抛出此异常。 实例 以下示例显示了java.util.Vector.clear()方法的用法。 package com.tutorialspoint; import java.util.Vector; public class VectorDemo { public static void main(String[] args) { // create an empty Vector vec with an initial capacity of 4 Vector<Integer> vec = new Vector<Integer>(4); // use add() method to add elements in the vector vec.add(4); vec.add(3); vec.add(2); vec.add(1); // let us print the size of the vector System.out.println("Size of the vector after addition :"+vec.size()); System.out.println("Added numbers are :- "); for (Integer number : vec) { System.out.println("Number = " + number); } // let us clear the vector vec.clear(); // let us print the size of the vector System.out.println("Size of the vector after clearing :"+vec.size()); } } 让我们编译并运行上面的程序,这将产生以下结果。调用clear()方法后向量的大小为0。 Size of the vector after addition :4 Added numbers are :- Number = 4 Number = 3 Number = 2 Number = 1 Size of the vector after clearing :0 java.util.Vector.capacity() java.util.Vector.clone()