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One of the common interview questions that occasionally comes up is What are the differences between the == and equals() methods for matching objects in Java? This topic is typically posed about strings since the equals() method and the == method provides different results when comparing strings. Along with other common String-related queries like StringBuffer vs StringBuilder, Because String is final, etc., I frequently encounter these. This article will attempt to comprehend this notion and distinguish between the == and equals methods in Java. Java is a purely object-oriented language, and each object has a single state and position in memory. Equals () and == are connected to the value and placement of the object.
What does the Java == operator and equals method do?
When comparing two objects in Java, both the equals() methods and the == operation are utilised. Equals() is a method, and == is an operator. But regardless of whether two objects in a heap point to the same address or not, the == operator checks their references or memory locations. Every time we construct an item using the new operator, a new memory is created for that object. Therefore, to determine if the memory address or location of two substances is the same or not, we utilise the == operator
The standard implementation of the equal() function, specified in the Object class, checks the object’s memory reference to see if it points to the same address. If it does, the two objects are considered equal. Since the object model is the parent of all other objects, each object has a default implementation; however, we can override the technique and provide our integration for determining whether two objects are equal. Most Java courses have their own equals method implementations that check the object’s components.
Considering java.lang. The string class overrides the equals() and the hashcode methods, and in the override methods, it is determined whether two strings contain the same data or character and, if so, whether they are equal. If not, they are not.
The distinction between Java's == and equals methods
It’s an opportunity to compare the objects now that we understand the equals function, how it checks objects, and what the equality operator (==) means. The following are some important distinctions between Java’s equals() function and == operator:
| == Operator | Equals() Method |
| In Java, == is regarded as an operator. | In Java, equals() is regarded as a method. |
| It is mostly used for comparing reference values and objects. | It is used to compare the object’s real content. |
| The == operator can be used with objects and primitives. | The equals method cannot be used with primitives. |
| Because the == operator cannot compare conflicting objects, the compiler reports a compile-time error. | The equals() method can be used to compare conflicting objects and returns “false.” |
| The operator == cannot be changed. | Equals() is a method that can be overridden. |
| we cannot alter the behaviour of the == operator. | we can always modify the equals() method and provide the criterion for the equal of the objects. |
Using Operators in Java
Using a single Java example, let’s explain all these variations between equals and the == operator:
String s1=new String(“hello”);
String s2=new String(“hello”);
We’ve constructed two strings, s1 and s2, and will now compare them using == or equals () methods to see if they’re equal. First, we compare using the equality operator ==, which only yields true if both reference variables refer to the same object.
if(s1==s2) {
System.out.println(“s1==s2 is TRUE”);
} else{
System.out.println(“s1==s2 is FALSE”);
}
Because we built two objects with distinct heap locations, the comparison’s output is FALSE because it can’t compare the reference or address locations of the objects, which would result in a false result. What will happen if we employ the equals technique to see whether they are equivalent now?
if(s1.equals(s2)) {
System.out.println(“s1.equals(s2) is TRUE”);
} else {
System.out.println(“s1.equals(s2) is FALSE”);
}
Because of java.lang, this comparison’s result is TRUE.
Since both have the value “hello,” these are equally based on the String class’s equals() function, which has already replaced the Object class’s equals() method.
