Java Stack trimToSize()方法及示例

Java中 Stack 的 trimToSize() 方法将一个Stack实例的容量修剪为列表的当前容量。该方法用于将一个Stack实例修剪成它所包含的元素数。

语法

public void trimToSize()

参数： 它不接受任何参数。

返回值： 它不返回任何值。它将这个堆栈实例的容量修剪成它所包含的元素的数量。

下面的程序说明了trimToSize()方法。

// Java code to demonstrate the working of
// trimToSize() method in Stack
  
// for Stack functions
import java.util.Stack;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Creating object of Stack<Integer>
        Stack<Integer>
            stack = new Stack<Integer>();
  
        // adding element to stack
        stack.add(10);
        stack.add(20);
        stack.add(30);
        stack.add(40);
  
        // Print the Stack
        System.out.println("Stack: " + stack);
  
        // Print the current capacity of Stack
        System.out.println("Current capacity of Stack: "
                           + stack.capacity());
  
        // Change the capacity to 15
        stack.ensureCapacity(15);
  
        // Print the current capacity of Stack
        System.out.println("New capacity of Stack: "
                           + stack.capacity());
  
        // trims the capacity to the number of elements
        stack.trimToSize();
  
        // Print the current capacity of Stack
        System.out.println("Current capacity of Stack"
                           + " after use of trimToSize() method: "
                           + stack.capacity());
    }
}

输出：

Stack: [10, 20, 30, 40]
Current capacity of Stack: 10
New capacity of Stack: 20
Current capacity of Stack after use of trimToSize() method: 4

例2 :

// Java program to demonstrate
// Stack toString() method
  
import java.util.*;
  
public class collection {
    public static void main(String args[])
    {
        // Creating an Empty Stack
        Stack<String> stack
            = new Stack<String>();
  
        // Use add() method
        // to add elements to the Collection
        stack.add("Welcome");
        stack.add("To");
        stack.add("Geeks");
        stack.add("For");
        stack.add("Geeks");
  
        // Print the Stack
        System.out.println("Stack: " + stack);
  
        // Print the current capacity of Stack
        System.out.println("Current capacity of Stack: "
                           + stack.capacity());
  
        // Change the capacity to 20
        stack.ensureCapacity(20);
  
        // Print the current capacity of Stack
        System.out.println("New capacity of Stack: "
                           + stack.capacity());
  
        // trims the capacity to the number of elements
        stack.trimToSize();
  
        // Print the current capacity of Stack
        System.out.println("Current capacity of Stack"
                           + " after use of trimToSize() method: "
                           + stack.capacity());
    }
}

输出：

Stack: [Welcome, To, Geeks, For, Geeks]
Current capacity of Stack: 10
New capacity of Stack: 20
Current capacity of Stack after use of trimToSize() method: 5