Java StringBuilder Class- StringBuilder Methods in Java

Written By The IoT Academy
Published on February 21st, 2023
Updated on October 31, 2023

StringBuilder in Java is a class used to build mutable, or changeable, strings of characters. The StringBuilder class acts as a replacement for the String Class in Java. It creates a mutable sequence of characters instead of an immutable one as the String Class does. The functions of the StringBuilder and StringBuffer classes are extremely similar because both create changeable sequences of characters as an alternative to the String Class. However, synchronization is where the StringBuilder class and StringBuffer class differ. Contrary to the StringBuffer class, the StringBuilder class does not guarantee synchronization.

Continue reading to learn more about StringBuilder in Java. With the help of a few examples from this class, learn how to use the StringBuilder class successfully.

Table of Contents

StringBuilder And StringBuffer In Java

The StringBuilder methods in Java represent a changeable string of characters. The StringBuffer class and the StringBuilder class are quite similar. Both of these classes provide changeable character sequences and are alternatives to the String class. Contrary to the StringBuffer class, the StringBuilder class does not guarantee synchronization. As a result, this class is intended to be utilized in areas where a single thread previously used the StringBuffer as a drop-in replacement (as is generally the case). It is advised to use this class instead of StringBuffer whenever possible because it will be faster in most implementations.

It is advised that multiple threads should not use StringBuilder instances. The use of StringBuffer is advised if such synchronization is necessary. Compared to a String buffer, String Builder performs well but is not thread-safe.
Some key points to define StringBuilder and StringBuffer in Java:-

Because the StringBuilder class is not thread-safe, its operations are faster than those of the StringBuffer class.
While the StringBuffer class operations are synchronized, the StringBuilder class does not ensure synchronization.
The StringBuilder class can be used since most actions on a string are done on the same thread.
Due to its quicker operations, the StringBuilder class is recommended over the StringBuffer class.

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StringBuilder Methods

Numerous methods are available in Java’s StringBuilder to execute various actions on the string builder. Some of the main StringBuilder class methods are below:

1. StringBuilder append (String s)

The mentioned string is added to the existing string using this approach. Additionally, you can use arguments like char, int, double, float, boolean, and more. Any datatype value that has to be appended to the StringBuilder sequence may be used as the method’s only input parameter.

2. StringBuilder insert (int offset, String s)

The mentioned string will be inserted into the other string at the provided offset location. Similar to append, this method can be overloaded with arguments such as (int, boolean), (int, int), (int, char), (int, double), (int, float), etc.

3. StringBuilder replace(int start, int end, String s)

The supplied string will be substituted for the original string from the start index to the finished index.

4. StringBuilder reverse()

For reversing the string. It doesn’t take any parameters and returns a StringBuilder reference.

5. StringBuilder delete(int start, int end)

By using this technique, the string will be removed from the start index to the end index as specified.

6. int capacity()

This will display the StringBuilder’s current capacity. The StringBuilder object’s capacity is returned by this method. The StringBuilder can store 16 bytes by default. When the StringBuilder’s capacity is exhausted, its new capacity will be (previouscapacity+1)X2.

7. void ensureCapacity(int min)

The capacity of the StringBuilder is guaranteed to be at least equal to the specified minimum by this method.

8. char charAt(int index)

The character located at the requested index will be returned. The character index is the only parameter required for this procedure. [0, SizeofStringBuilder-1] is the required index range. If the index value is outside of the acceptable range, an indexoutofException is thrown, and the program is terminated.

9. int length()

The length (total characters) of the string can be obtained using this method.

10. String substring(int start, int end)

The substring from the start index to the end index will be returned. The start index of the sequence and the ending index of the sequence are the two parameters required by this approach. Greater than 0 and smaller than or equal to the ending index are the main requirements for the starting index.

11. int indexOf(String str)

The index of the first occurrence of the provided string will be returned by this method.

12. Void trimToSize()

It will make an effort to make the StringBuilder smaller.

StringBuilder in Java Example

Let’s understand the concept of StringBuilder with the help of examples:-

1. StringBuilder insert() method

class StringBuilderdemo{
public static void main(String args[]){
StringBuilder sb=new StringBuilder(“Hi “);
sb.insert(1,”Hey”);//now original string is changed
System.out.println(sb);//prints HHeyi
}
}
Output: HHeyi

2. StringBuilder replace() method

class StringBuilderdemo2{
public static void main(String args[]){
StringBuilder sb=new StringBuilder(“Hello”);
sb.replace(1,3,”Hey”);
System.out.println(sb);//prints HHeylo
}
}
Output: HHeylo

3. StringBuilder delete() method

class StringBuilderdemo3
{
public static void main(String args[])
{
StringBuilder sb=new StringBuilder(“Java”);
sb.delete(1,3);
System.out.println(sb);//prints Ja
}
}
Output: Ja

Constructors In StringBuilder

1. StringBuilder()

It will create a string builder with 16 characters as the initial capacity and no characters.

2. StringBuilder(int capacity)

A string builder is created with a starting capacity determined by the capacity parameter without any characters in it.

3. StringBuilder(CharSequence seq)

It will create a string builder using the same characters as the supplied CharSequence.

4. StringBuilder(String str)

It will make a string builder with the specified string’s contents as its starting value.

Conclusion

It’s all about the Java StringBuilder class, and we’ve seen some of its methods in action. We have examined some examples of these techniques. The StringBuilder class in Java includes several methods that can be utilized and are useful in a variety of situations. When compared to other string classes, the StringBuilder class performs better, but it is not thread-safe and offers more methods for a variety of uses. The StringBuilder class is recommended when manipulating characters in our string because the heap area of the memory allocates memory for it. To learn more about Java, join the Full Stack Java Developer Course offered by E & ICT Academy IIT Guwahati.

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The IoT Academy

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