equals and equalsIgnoreCase

Learn string comparison with equals().

equals and equalsIgnoreCase

To compare the content of two Strings use equals. The == operator compares references, so for Strings equals is preferred.

String a = "Hello";
String b = "Hello";
System.out.println(a.equals(b));         // true
System.out.println(a.equalsIgnoreCase(b)); // true (case insensitive)

equalsIgnoreCase ignores case differences. "JAVA".equalsIgnoreCase("java") returns true.

The most common mistake in String comparison is using ==.

Exercise Compare with equals

Write a Main class with a main method. Assign "Hello" to String a and "hello" to String b. Print a.equals(b) and a.equalsIgnoreCase(b) with println.

Show example solution

public class Main {
    public static void main(String[] args) {
        String a = "Hello";
        String b = "hello";
        System.out.println(a.equals(b));
        System.out.println(a.equalsIgnoreCase(b));
    }
}

Why does == not work?

Strings are reference types. == checks whether two variables point to the same object, not whether their content matches.

String a = "Hello";
String b = new String("Hello");
System.out.println(a == b);       // false!
System.out.println(a.equals(b)); // true

Java pools (interns) some Strings, so == may sometimes return true. But this is not reliable; always use equals.

Test yourself

Match the methods

equals

Content equal
equalsIgnoreCase

Case insensitive
==

Reference compare
!=

Not equal
What does "JAVA".equalsIgnoreCase("java") return?
- false
- true
- null
- Error
Show answer

true — equalsIgnoreCase ignores case differences.

Complete the equals call

boolean same = a.____(b);

Show answer

boolean same = a.equals(b);

Next lesson: indexOf and substring

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