Why printing "" + variables output each variable individually without spacing?

One of my assignments has this code:

    System.out.println("" + x + y + count);

that outputs the value of x, y and count individually without any spaces. I would like to know more about it online. However, I can't seem to find the right keywords to search it up online. Can someone please explain to me the logic behind this or perhaps point to me a name or keyword for such a situation?

I have always known the " " as a tool to print out a string so I'm confused by this.

Thanks in advance.

Or you can use String format like this:

System.out.printf("%d%d%d", x, y, count);

If we apply standard Java precedence rules, the statement:

System.out.println("" + x + y + count);

is equivalent to

System.out.println((("" + x) + y) + count);

Then we look at the meaning of +

• If the static types of both a and b are numeric types (either primitive numeric or their boxed types) then a + b is numeric addition.

• Otherwise, a + b is string concatenation. The two arguments are converted to strings and the strings are concatenated.

Based on this we can say that all of the + operators in the example will be treated as string concatenations.

If you want spaces between x, y and count you need to add some string literals; e.g.

System.out.println("" + x + " " + y + " " + count);

or, more simply:

System.out.println(x + " " + y + " " + count);

If you wanted x, y and count to be added (assuming that they are numeric), then you could write this:

System.out.println("" + (x + y + count));

or, more simply:

System.out.println(x + y + count);

The latter is using a different overload of println.

> I have always known the "" as a tool to print out a string so I'm confused by this.

Ummm ... it is actually an empty string literal. The usage "" + x is simply an idiom for converting x to a String. The empty string literal has other uses too. The main one is to represent a String with zero characters.

The "" is an empty String. In Java when you concatenate a String with other primitives that can be cast to String the result is a String. That means that the code

System.out.println("" + something);

is a different way to write

System.out.println(String.valueOf(something));

However in your scenario the "" + x + y + count means that the elements are converted to String and then concatenated - this means that if x==1, y==2, count==3 the result would be 123. If you wanted to just cast the result to String you would have to indicate that the computation should happen before casting to String for example by using brackets

System.out.println("" + (x+y+count));

The output of this would be 6.