CODEWITHSUNDEEP
javamethodsbooleanreturnequals
user3029345
user3029345

Reputation:

Whats wrong with this boolean method?

Hi I have this method which I created. Its job is to receive an Integer A, which can either be 10 or 30. It is meant to return TRUE if the value is ten, and false otherwise.

public static boolean checkStatus(int a){
        if(a.equals(10)){
              return true;
        }
      return false;
    }

For some reason I am getting a compilation error in the if(a.equals(10)) condition, which says INT CANNOT BE DEREFERNCED. If I'm not mistaken, isn't the .equals() method the way to go in this circumstance?

Thanks for your help!

Upvotes: 1

Views: 455

Answers (8)

SkyWalker
SkyWalker

Reputation: 29140

equals is used for non-primitives basically for Objects.

== is used for primitives.

So, you can use it

public static boolean checkStatus (int a) {
    if (a == 10)
        return true;
   return false;
}

Example 1: For object, if equals method are overridden, then "equals" method will return true.

public class Employee {
    int id;

    @Override
    public boolean equals(Object obj) {
        Employee e = (Employee) obj;
        return id == e.id;
    }

    Employee(int id) {
        this.id = id;
    }

    public static void main(String[] args) {
        Employee e1 = new Employee(5);
        Employee e2 = new Employee(5);
        System.out.println("e1.equals(e2) is: " + e1.equals(e2));
        System.out.println("(e1 == e2) is: " + (e1 == e2));
    }
}

Output:

e1.equals(e2) is: true

(e1 == e2) is: false

Example 2: For object, if equals method are not overridden, then "equals" method works as "=="

public class Employee {
    int id;

    Employee(int id) {
        this.id = id;
    }

    public static void main(String[] args) {
        Employee e1 = new Employee(5);
        Employee e2 = new Employee(5);
        System.out.println("e1.equals(e2) is: " + e1.equals(e2));
        System.out.println("(e1 == e2) is: " + (e1 == e2));
    }
}

Output:

e1.equals(e2) is: false

(e1 == e2) is: false

Here "equals" method works as "==". So, don't forget to override the equals method for object.

Upvotes: 1

Sukhmeet Singh
Sukhmeet Singh

Reputation: 29

You can of course wrap the integer up as :

Integer i = new Integer(a);

Then the equals function can be used with 'i', the new Integer object.

Upvotes: 0

paxdiablo
paxdiablo

Reputation: 881303

You can use equals for objects but an int is a primitive type (a), rather than an object.

Hence you need something like:

public static boolean checkStatus (int a) {
    if (a == 10)
        return true;
   return false;
}

or the shorter and more sensible (in this case):

public static boolean checkStatus (int a) {
    return (a == 10);
}

(a) The purists will argue this is proof that Java is not really an object-oriented language, but that's because they're raving loonies :-)

Upvotes: 5

Nauman Afzaal
Nauman Afzaal

Reputation: 1046

You can do something like this with Integer Class

  Integer x = 5;
  Integer y = 10;
  Integer z =5;
  Short a = 5;

  System.out.println(x.equals(y));  
  System.out.println(x.equals(z)); 
  System.out.println(x.equals(a));

Output: 

  false
  true
  false

Upvotes: 0

codeMan
codeMan

Reputation: 5758

int is a primitive in Java and primitives does not have behaviours a.k.a methods.

hence you cannot call .equals on int. So the options here are to use a == 

public static boolean checkStatus(Integer a){
  return (a==10);
}

or convert the int to Integer which is a wrapper class 

public static boolean checkStatus(Integer a){
    return a.equals(10);
}

Upvotes: 0

Ruchira Gayan Ranaweera
Ruchira Gayan Ranaweera

Reputation: 35557

equals() method belongs to Object class of Java and it has to override each and every Object classes like String, Integer and MyObject(implemented class). But int is not a Java Object and there is no equals() method there.

you can just use == with int values and you can simplify your code as bellow. 

public static boolean checkStatus(int a){
    return a==10;
}

Upvotes: 1

Pracede
Pracede

Reputation: 4361

You can use 

public static boolean checkStatus(int a){
        if(a==10){
              return true;
        }
      return false;
    }

or 

public static boolean checkStatus(Integer a){

        if(a.equals(new Integer(10))){
              return true;
        }
      return false;
    }

Upvotes: 1

Kon
Kon

Reputation: 10810

Primitives in Java (int, long, float, etc..) don't have member methods, so the call

if (a.equals(10))

will not compile, as you're trying to de-reference a primitive. Instead, you want to use the == operator to compare primitive values:

if (a == 10)

and reserve the use of the equals() method for non-primitive Objects

Upvotes: 8

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