How to Use Java String Class equals() Method

Page Contents

Function Description

This method is used to compare the Java String with the specified object. It returns boolean true/false value. It is case sensitive during comparison. Both String objects will be equal only if both have the same sequence of characters as well as the same character case(lowercase/uppercase).

For Example: If you have 4 String objects str1, str2, str3, and str4 with values respectively “example”, “EXAMPLE” “Example” and “example”, then only str1 and str4 will be equal by this function, because these two objects have the same sequence of characters as well as same lowercase characters.

//string in lowercase

String str1 = "example";

// string in uppercase

String str2 = "EXAMPLE";

// string in camelcase

String str3 = "Example";

// string in lowercase

String str4 = "example";

Method Signature

public boolean equals(Object anObject)

Parameter

anObject : object to be compared with string.

Return Type

The Return Type is Boolean. It returns true if the passing object is not null, a string object and has the same sequence of characters. It is case sensitive during comparison.

Example of Java String Class equals() Method

public class ExampleStringEquals {
 
    private void areStringsEquals(String stringParam) {

          // string in lowercase

          String str1 = "example";

          // string in uppercase

          String str2 = "EXAMPLE";

          // string in camelcase

          String str3 = "Example";
 
          // Both strings are in lowercase, check for equality

          System.out.println("Both strings are in lowercase. check if both are equal : " + stringParam.equals(str1));
 
          // One string in lowercase and one in uppercase. check equality
          
          System.out.println(
          
              "One string in lowercase and one in uppercase.check if both are equal : " + stringParam.equals(str2));
 
          // One string in lowercase and one in camelcase. check equality

          System.out.println(
                       
               "One string in lowercase and one in camelcase. check if both are equal : " + stringParam.equals(str3));
 

    }
 
    public static void main(String[] args) {

          String str = "example";

          ExampleStringEquals example = new ExampleStringEquals();

          example.areStringsEquals(str);

    }
 
}

 
Output:

Both strings are in lowercase. check if both are equal : true

One string in lowercase and one in uppercase.check if both are equal : false

One string in lowercase and one in camelcase. check if both are equal : false

Example to compare with null object

public class ExampleStringEquals {

public static void main(String[] args) {


String str = "example";

System.out.println("comparing with null object : " + 

str.equals(null));

}

}


Output:

comparing with null object : false

Example to check equals() bypassing any other object

public class ExampleStringEquals {


public static void main(String[] args) {

String str = "example";

Integer testValue = new Integer(12);

System.out.println("comparing with Integer object : " + 

str.equals(testValue));

}

}

Output: 
comparing with Integer object : 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	boolean contains(CharSequence s)	Returns boolean value(true/false). It searches the given sequence of characters within the string and returns true/false accordingly. Characters will be case sensitive while searching in string.
8	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.
9	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.
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 the equals() method of String class with examples. Apart from the equals() 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.