String Equals vs == Operator Example in Java

Introduction

Comparing strings is one of the most common tasks in Java, but beginners often confuse the == operator with the equals() method. This program demonstrates both and explains when each is appropriate.

Key Difference

Example Program

public class StringCompareDemo {
    public static void main(String[] args) {
        String a = new String("Java");
        String b = new String("Java");
        String c = "Java";
        String d = "Java";

        System.out.println("a == b        : " + (a == b));
        System.out.println("a.equals(b)   : " + a.equals(b));
        System.out.println("c == d        : " + (c == d));
        System.out.println("c.equals(d)   : " + c.equals(d));

        String s1 = "hello";
        String s2 = "HELLO";
        System.out.println("s1.equals(s2)            : " + s1.equals(s2));
        System.out.println("s1.equalsIgnoreCase(s2)  : " + s1.equalsIgnoreCase(s2));
    }
}

Sample Output

a == b        : false
a.equals(b)   : true
c == d        : true
c.equals(d)   : true
s1.equals(s2)            : false
s1.equalsIgnoreCase(s2)  : true

How It Works

• new String("Java") creates distinct objects on the heap, so a == b is false even though the text matches.
• String literals "Java" are interned in the string pool; c and d refer to the same pooled object, so c == d is true.
• For content comparison, always prefer equals() or equalsIgnoreCase().

Best Practices

• Use equals() for almost all String content checks.
• Use Objects.equals(a, b) when either operand may be null.
• Never use == to compare user-entered or dynamically built strings.

Common Mistakes

• Using == after reading input with Scanner and expecting content equality.
• Calling equals() on a literal with a possibly-null variable — reverse the call: "fixed".equals(variable).