Function Description

The Java String class contains() method is used to verify/search a specified sequence of characters in the string. It is case sensitive and checks the sequence of character as well as the case of the character(s). It returns true if the specified sequence of character(s) found in the string otherwise false.

Method Signature

public boolean contains(CharSequence charseq)

Parameters

charseq : sequence of characters to be verified in string.

Return Type

Boolean (true/false).  Return true if the sequence of characters and case (lowercase/ uppercase) of the characters exists otherwise false.

Example Of Java String Class contains() Method

package com.java.test;
 
public class ExampleStringContains {
   
    public static void main(String[] args) {

    String str = "Welcome to String contains function learning";
         
    //return true as str object contains ‘learning’ charsequence
          
    boolean isContainsLearning = str.contains("learning");
         
    System.out.println("Return true if String contains learning charsequence : "+isContainsLearning);
         
    //return false as str object does not contain uppercase 'L' ‘Learning’ charsequence

    isContainsLearning = str.contains("Learning");
         
     System.out.println("Return false if String does not contain uppercase 'L' Learning charsequence : "+isContainsLearning);
         
    }
 
}
 
Output :

Return true if String contains learning charsequence : true

Return false if String does not contain uppercase 'L' Learning charsequence : false

Other Methods of String Class

Sequence	Method	Description
1	char charAt(int index)	This method is used to return the character of the string at specified index. First character is at index 0 while last is at string length-1 . StringIndexOutOfBounds Exception is thrown if valid index value is not passed.
2	int length()	Returns the number of characters count  in  a string.
3	static String format(String format, Object… args)	Return the formatted String. It is a static method and formats the string as per passing format and argument(s).
4	static String format(Locale l, String format, Object… args)	Return the formatted String. It is a static method and formats the string as per passing format and argument(s) and locale.
5	String substring(int beginIndex)	Returns substring from the given index position to the end index of the string.
6	String substring(int beginIndex, int endIndex)	Returns substring from the specified begin index to the specified end index.
7	static String join(CharSequence delimiter, CharSequence… elements)	Returns joined string. This method joins each passing String using the specified delimiter. It is a static method.
8	static String join(CharSequence delimiter, Iterable<? extends CharSequence> elements)	Returns the joined string. This method joins each passing string object of an iterate object using the specified delimiter and returns the concatenated string. It is a static method.
9	boolean equals(Object another)	Returns boolean value(true/false). It checks the equality of string with the passing object.
10	boolean isEmpty()	Returns boolean value(true/false). It returns true if the string is empty otherwise returns false.
11	String concat(String str)	Returns the concatenating string. It concatenates the passing string at the end of the string.
12	String replace(char old, char new)	Return the replaced string. It replaces all occurrences of the specified character with the new character.
13	String replace(CharSequence old, CharSequence new)	Return the replaced string. It replaces all occurrences of the specified Character sequence with the specified new Character sequence.
14	String replaceAll(String regex, String replacement)	Returns the replaced string. It replaces all occurrences of the sequence of characters with the given replacement string that are matching with the given regular expression.
15	String replaceFirst(String regex, String replacement)	Returns the replaced string. It replaces the first matching sequence of characters with the replacement string that matches with the given regular expression.
16	static boolean equalsIgnoreCase(String another)	Returns the boolean (true/false) value. It compares the passing string with string by ignoring the case. It  compares the content irrespective of lowercase or uppercase of the character(s).
17	String[] split(String regex)	Returns the array of strings resulting from splitting of the string     around matches of the given regular expression. String is breaked into strings from all  the matching regular expressions.
18	String[] split(String regex, int limit)	Returns the array of strings resulting from splitting of the string     around matches of the given regular expression. It breaks the string from all the matching regular expression upto the given limit.
19	String intern()	Returns an interned string. This method helps to compare two objects using == operator and checks in a string constant pool. it is faster for comparison.
20	int indexOf(int ch)	Returns the index value of first occurrence of the specified character within the string
21	int indexOf(int ch, int fromIndex)	Returns the index value of first occurrence of the specified character from the substring starting from specified index
22	int indexOf(String substring)	Returns the index value of first occurrence of the specified substring within the string.
23	int indexOf(String substring, int fromIndex)	Returns the index value of the first occurrence of the specified string within the substring starting from specified index to end of the string index.
24	int lastIndexOf(int ch)	Returns the index value of last occurrence of the specified character
25	int lastIndexOf (int ch, int fromIndex)	Returns the index value of last occurrence of the specified character, search starts at given fromIndex.
26	int lastIndexOf (String str)	Returns the index value of last occurrence of the specified string.
27	int lastIndexOf (String str, int fromIndex	Returns the index value of last occurrence of the specified string, searches start from given fromIndex
28	String toLowerCase()	Returns all the characters of the string in lowercase .
29	String toLowerCase(Locale l)	Returns all the characters of the string in lowercase using specified locale.
30	String toUpperCase()	Returns all the characters of the string in uppercase.
31	String toUpperCase(Locale l)	Returns all the characters of the string in uppercase using specified locale.
32	String trim()	Returns the string after removing the white space from the beginning and end of the string.
33	static String valueOf(int value)	Return the converted string. It converts the objects and all primitive types of values into string. It is a static method.

In this article, we learned all about contains() method of String class with examples. Apart from contains() method we got an idea about other String methods too. We will come up with more articles explaining other String methods with examples. For more details please click on the respective methods link.