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java lang StringBuilder Class

java lang StringBuilder Class

java.lang.StringBuilder Class

StringBuilder Class in Java

A mutable sequence of characters. Java StringBuilder class provides an API compatible with Java StringBuffer, but with no guarantee of synchronization. Java StringBuilder class is designed for use as a drop-in replacement for Java StringBuffer in places where the Java StringBuffer was being used by a single thread. It is recommended that Java StringBuilder class be used in preference to Java StringBuffer as it will be faster under most implementations.

Every string builder has a capacity. As long as the length of the character sequence contained in the string builder does not exceed the capacity, it is not necessary to allocate a new internal buffer. If the internal buffer overflows, it is automatically made larger.

Instances of StringBuilder are not safe for use by multiple threads. If such synchronization is required then it is recommended that StringBuffer be used.

Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown.

Note :

StringBuilder implements Comparable but does not override equals. Thus, the natural ordering of StringBuilder is inconsistent with equals. Care should be exercised if StringBuilder objects are used as keys in a SortedMap or elements in a SortedSet. See Comparable, SortedMap, or SortedSet for more information.

What are the principal operations on a StringBuilder in Java ?

The principal operations on a StringBuilder are the append and insert methods, which are overloaded so as to accept data of any type. Each effectively converts a given datum to a string and then appends or inserts the characters of that string to the string builder. The append method always adds these characters at the end of the builder; the insert method adds the characters at a specified point.

For example, if z refers to a string builder object whose current contents are "start", then the method call z.append("le") would cause the string builder to contain "startle", whereas z.insert(4, "le") would alter the string builder to contain "starlet".

In general, if sb refers to an instance of a StringBuilder, then sb.append(x) has the same effect as sb.insert(sb.length(), x).

Following Java StringBuilder class example you can learn how to create Java StringBuilder and how to use Java StringBuilder.

Java StringBuilder Example with Default Constructor

/* Java StringBuilder Example with Default Constructor */
/* Save with file name StringBuilderExample1.java */

public class StringBuilderExample1
{
	public static void main(String args[])
	{
		//Java StringBuilder DECLARATION

		StringBuilder s1;

		//CREATE Java StringBuilder INSTANCE USING DEFAULT CONSTRUCTOR
		//THE VALUE OF STRINGBUILDER IS EMPTY

		s1 = new StringBuilder();

		//Java StringBuilder OUTPUT EMPTYSTRING

		System.out.println("StringBuilder value : " + s1);
	}
}

Java StringBuilder Example with Parameter Constructor

/* Java StringBuilder Example with Parameter Constructor */
/* Save with file name StringBuilderExample2.java */

public class StringBuilderExample2
{
	public static void main(String args[])
	{
		//Java StringBuilder DECLARATION

		StringBuilder s1;

		//CREATE Java StringBuilder INSTANCE USING PARAMETER CONSTRUCTOR

		s1 = new StringBuilder("Huda Tutorials");

		//Java StringBuilder OUTPUT

		System.out.println("StringBuilder value : " + s1);
	}
}

How to Reverse String in java using StringBuilder ?

By using the Java StringBuilder class you can reverse the string in java. In the following Java StringBuilder example you can learn how to reverse string in java using StringBuilder.

Most of the interviewer ask a question "How to reverse String in java?". Most of the people fail in this question. Because those are worked on String class not worked on StringBuilder class.

Following Java StringBuilder class example you can learn how to reverse string using StringBuilder.

How to reverse string using Java StringBuilder

/* Java StringBuilder Example with how to reverse string in java */
/* Save with file name StringBuilderExample3.java */

public class StringBuilderExample3
{
	public static void main(String args[])
	{
		//Java StringBuilder DECLARATION

		StringBuilder s1;

		//CREATE Java StringBuilder INSTANCE USING PARAMETER CONSTRUCTOR

		s1 = new StringBuilder("abcd");

		//Java StringBuilder REVERSE STRING USING REVERSE METHOD

		System.out.println("Reverse String is : " + s1.reverse());
	}
}

Following Java StringBuilder class example you can learn how to append String into Java StringBuilder.

How to append String into Java StringBuilder

/* Java StringBuilder Example with how to append String into Java StringBuilder */
/* Save with file name StringBuilderExample4.java */

public class StringBuilderExample4
{
	public static void main(String args[])
	{
		//Java StringBuilder DECLARATION

		StringBuilder s1;

		//CREATE Java StringBuilder INSTANCE USING PARAMETER CONSTRUCTOR

		s1 = new StringBuilder("Huda");

		s1.append("Tutorials");

		//Java StringBuilder APPENDED STRING

		System.out.println("String is : " + s1.toString());
	}
}
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