Does Java implicitly convert int to String when using the "+" operator on int + String operation?

I have the following code:

    System.out.println("12" + 34);    // prints "1234"

	System.out.println(1 + 2 + "34"); // prints "334"

I was expecting an error, instead, my int values got concatenated to the String without error.

Can someone explain in detail what goes on above?

1. Does Java implicitly convert int to String type when it notices an int AND String data type in a "+" operation?

2. Why isn't there an error thrown due to wrong data types when using the + operator?

3. If there were indeed implicit conversion going on, why does Java do that and not throw an error?

This answer addresses your second example:

 System.out.println(1 + 2 + "34"); // prints "334"

What is happening here is that the expression 1 + 2 is happening first, due to the left-to-right precedence of the + operator. Actually, any operator has left to right precedence all other things being of the same precedence. So, first 1 + 2 evaluates as integer addition to 3, leaving us with:

 System.out.println(3 + "34"); // prints "334"

Next, 3 + "34" evaluates as string concatenation, similar to your first example, printing "334".

It is java concatenate. please refer the link.

> https://stackoverflow.com/questions/12028779/concatenating-string-and-numbers-java