String slicing in Java

String slicing is about fetching a sub string from given string. Java String class provides subString method to fetch a sub string from given string.

 

subString method is available in below overloaded forms.

public String substring(int beginIndex)
public String substring(int beginIndex, int endIndex)

 

Get the substring from starting index

‘substring(int beginIndex)’ method returns a string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string. Here the beginIndex is inclusive.

String str1 = "hello world";
String subStr1 = str1.substring(6); // Return 'world'

 

'subString' method throws StringIndexOutOfBoundsException, if beginIndex is negative or larger than the length of this String object.

 

Get the substring between start and end indexes

‘substring(int beginIndex, int endIndex)’ method returns a string that is a substring of this string. The substring begins at the specified beginIndex and extends to the character at index endIndex - 1. Thus the length of the substring is endIndex-beginIndex. Here the the beginning index is inclusive and endIndex is exclusive.

 

String str2 = "Java is a high level programming language";
String subStr2 = str2.substring(10, 14); // Return 'high'

'subString' method throws StringIndexOutOfBoundsException, if the beginIndex is negative, or endIndex is larger than the length of this String object, or beginIndex is larger than endIndex.

 

Find the below working application.

 

SubStringDemo1.java

package com.sample.app.strings;

public class SubStringDemo1 {

	public static void main(String[] args) {
		String str1 = "hello world";
		String subStr1 = str1.substring(6); // Return world

		System.out.println("str1 : " + str1);
		System.out.println("subStr1 : " + subStr1);

		// Throws StringIndexOutOfBoundsException if beginIndex is negative or larger
		// than the length of this String object
		try {
			str1.substring(-1);
		} catch (StringIndexOutOfBoundsException e) {
			System.err.println(e);
		}

		try {
			str1.substring(100);
		} catch (StringIndexOutOfBoundsException e) {
			System.err.println(e);
		}

		String str2 = "Java is a high level programming language";
		String subStr2 = str2.substring(10, 14); // Return 'high'

		System.out.println("\nstr2 : " + str2);
		System.out.println("subStr2 : '" + subStr2 + "'");

		// throws StringIndexOutOfBoundsException, if the beginIndex is negative, or
		// endIndex is larger than the length of this String object, or beginIndex is
		// larger than endIndex.
		try {
			str2.substring(-1, 5);
		} catch (StringIndexOutOfBoundsException e) {
			System.err.println(e);
		}

		try {
			str2.substring(5, 100);
		} catch (StringIndexOutOfBoundsException e) {
			System.err.println(e);
		}

		try {
			str2.substring(5, 1);
		} catch (StringIndexOutOfBoundsException e) {
			System.err.println(e);
		}
	}

}

 

Output

str1 : hello world
subStr1 : world
java.lang.StringIndexOutOfBoundsException: begin -1, end 11, length 11
java.lang.StringIndexOutOfBoundsException: begin 100, end 11, length 11

str2 : Java is a high level programming language
subStr2 : 'high'
java.lang.StringIndexOutOfBoundsException: begin -1, end 5, length 41
java.lang.StringIndexOutOfBoundsException: begin 5, end 100, length 41
java.lang.StringIndexOutOfBoundsException: begin 5, end 1, length 41

 

References

https://docs.oracle.com/en/java/javase/18/docs/api/java.base/java/lang/String.html

 

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