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"===" equivalent in Java

While comparing two values in Java, how do you test if both, the type and the value, are equivalent?

I know in JavaScript === can be used to accomplish this, so I tried that in Java, but it didn’t work.

I know this is a simple question, but I tried looking it up and I couldn’t find out what it was.

Answer*

**TL;DR**

In Java there is not such a comparison operator: `===`, but `==` or `equals`

**A longer explanation**

In _weakly typed_ languages such as JavaScript you can use the strict comparison operator (`===`) because the language allows comparison between variables which have different _types_.

For example, in JavaScript, you won't get a _compile error_ if you do this:

 var x = 10;
 var y = 'foo';
 console.log(x == y); // false


And it is useful, when you want to compare variables which may hold values that are "equals" but may be of different types.

For example

 var x = 10;
 var y = '10';
 console.log(x == y) // true
 console.log(x === y) // false

In _strongly typed_ languages such as Java, you don't need to use a strict comparison operator because the language already "handles" the type comparison.

For example:

 int x = 10;
 String y = "10";
 System.out.println("10" == y); // true
 System.out.println(x == y); // compile error : Incompatible operand types int and String

So, basically, in Java, there is no need for checking for strictness using `===` (a *syntax error* is reported).

In the first place, the compiler will complain when you compare values of different types using the `==` operator and [conversion][1] cannot be performed.

In the previous example of Java code, if you want to make a comparison between `x` and `y` you could use `equals`:

 int x = 10;
 String y = "10";
 System.out.println(y.equals(x)); // compile warning: Unlikely argument type for equals(): int seems to be unrelated to String

As a side note, notice the [`equals`][2] method cannot be called on primitive types.

Some useful readings are:

- [15.21. Equality Operators][3]
- https://stackoverflow.com/questions/2690544/what-is-the-difference-between-a-strongly-typed-language-and-a-statically-typed
- [What issues should be considered when overriding equals and hashCode in Java?][4]


 [1]: https://docs.oracle.com/javase/specs/jls/se8/html/jls-5.html#jls-5.1.8
 [2]: https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#equals(java.lang.Object)
 [3]: https://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.21
 [4]: https://stackoverflow.com/q/27581/5640649

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What about in Java 10 where you can now use var?

Nexevis
– Nexevis

2019年06月20日 12:04:14 +00:00
Commented Jun 20, 2019 at 12:04
1

@lealceldeiro JavaScript doesn't have doubles or integers. Just "Numbers" which are essentially doubles. So 10 and 10.0 are both the same.

Ivar
– Ivar

2019年06月20日 12:26:16 +00:00
Commented Jun 20, 2019 at 12:26
1

@JavaCakes They write the same thing for me (1, 2).

Ivar
– Ivar

2019年06月20日 17:40:27 +00:00
Commented Jun 20, 2019 at 17:40
2

@Nexevis var in Java 10 is pure syntactic sugar to avoid writing the declaration type of the variable when it can be inferred from the created instance. The language is still strongly-typed.

M A
– M A

2019年06月24日 19:30:54 +00:00
Commented Jun 24, 2019 at 19:30
1

TL;DR: === in Java is .equals()

Cees Timmerman
– Cees Timmerman

2023年04月17日 08:07:56 +00:00
Commented Apr 17, 2023 at 8:07

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"===" equivalent in Java

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