Java Vector trimToSize() Method

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Description

The Java Vector trimToSize() method is used to trim the capacity of this vector to be the vector's current size. If the capacity of this vector is larger than its current size, then the capacity is changed to current size.

Declaration

Following is the declaration for java.util.Vector.trimToSize() method

public void trimToSize()

Parameters

NA

Return Value

NA

Exception

NA

Trimming a Vector of Integer to a size Example

The following example shows the usage of Java Vector trimToSize() method. We're adding couple of Integers to the Vector object using add() method calls per element and capacity of vector is printed. Then we trimmed the vector using trimToSize() and its capacity is printed again to reflect the changes.

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<>(10);

      // 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: "+vec.capacity());

      // trim the size of the vector
      System.out.println("Trimming the vector");
      vec.trimToSize();

      System.out.println("Size of the vector: "+vec.capacity());
   }     
}

Output

Let us compile and run the above program, this will produce the following result.

Size of the vector: 10
Trimming the vector
Size of the vector: 4

Trimming a Vector of String to a size Example

The following example shows the usage of Java Vector trimToSize() method. We're adding couple of Strings to the Vector object using add() method calls per element and capacity of vector is printed. Then we trimmed the vector using trimToSize() and its capacity is printed again to reflect the changes.

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<String> vec = new Vector<>(10);

      // use add() method to add elements in the vector
      vec.add("Welcome");
      vec.add("To");
      vec.add("Tutorialspoint");

      // let us print the size of the vector
      System.out.println("Size of the vector: "+vec.capacity());

      // trim the size of the vector
      System.out.println("Trimming the vector");
      vec.trimToSize();

      System.out.println("Size of the vector: "+vec.capacity());
   }     
}

Output

Let us compile and run the above program, this will produce the following result.

Size of the vector: 10
Trimming the vector
Size of the vector: 3

Trimming a Vector of Object to a size Example

The following example shows the usage of Java Vector trimToSize() method. We're adding couple of Student objects to the Vector object using add() method calls per element and capacity of vector is printed. Then we trimmed the vector using trimToSize() and its capacity is printed again to reflect the changes.

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<Student> vec = new Vector<>(10);

      // use add() method to add elements in the vector
      vec.add(new Student(1, "Julie"));
      vec.add(new Student(2, "Robert"));
      vec.add(new Student(3, "Adam"));

      // let us print the size of the vector
      System.out.println("Size of the vector: "+vec.capacity());

      // trim the size of the vector
      System.out.println("Trimming the vector");
      vec.trimToSize();

      System.out.println("Size of the vector: "+vec.capacity());
   }     
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Size of the vector: 10
Trimming the vector
Size of the vector: 3