Java StringBuilder trimToSize() Method

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The StringBuilder.trimToSize() method in Java is used to trim the capacity of the StringBuilder object to be equal to the current length of the character sequence. This guide will cover the method's usage, explain how it works, and provide examples to demonstrate its functionality.

Table of Contents

1. Introduction
2. trimToSize Method Syntax
3. Examples
   • Trimming Capacity to Size
   • Checking Capacity Before and After Trimming
4. Conclusion

Introduction

The StringBuilder.trimToSize() method is a member of the StringBuilder class in Java. It allows you to reduce the capacity of the StringBuilder object to match its current length. This can be useful for optimizing memory usage when you no longer need the extra capacity that was initially allocated.

trimToSize Method Syntax

The syntax for the trimToSize method is as follows:

public void trimToSize()

This method does not take any parameters and does not return any value. It adjusts the capacity of the StringBuilder object to be equal to its current length.

Examples

Trimming Capacity to Size

The trimToSize method can be used to reduce the capacity of a StringBuilder to match its current length.

Example

public class StringBuilderTrimToSizeExample {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder(50); // Initial capacity of 50
        sb.append("Hello, World!");

        System.out.println("Initial capacity: " + sb.capacity());

        sb.trimToSize();

        System.out.println("Capacity after trimToSize: " + sb.capacity());
    }
}

Output:

Initial capacity: 50
Capacity after trimToSize: 13

Checking Capacity Before and After Trimming

You can check the capacity of the StringBuilder before and after calling the trimToSize method to see how the capacity changes.

Example

public class StringBuilderTrimToSizeExample {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder(100); // Initial capacity of 100
        sb.append("Java Programming");

        System.out.println("Initial capacity: " + sb.capacity());
        System.out.println("Length: " + sb.length());

        sb.trimToSize();

        System.out.println("Capacity after trimToSize: " + sb.capacity());
        System.out.println("Length after trimToSize: " + sb.length());
    }
}

Output:

Initial capacity: 100
Length: 16
Capacity after trimToSize: 16
Length after trimToSize: 16

In this example, the initial capacity of the StringBuilder is 100. After calling trimToSize(), the capacity is reduced to match the current length of 16 characters.

Conclusion

The StringBuilder.trimToSize() method in Java is used for optimizing memory usage by reducing the capacity of a StringBuilder object to match its current length. By understanding how to use this method, you can efficiently manage the memory allocated for your StringBuilder objects. Whether you need to trim the capacity to size or check the capacity before and after trimming, the trimToSize method provides a reliable solution for these tasks.