Weird behavior of println() method in Java

Question

class W {
    static int count=0;

    W() {
        count++;
        System.out.print("c ");
    }

    public static void main(String[] args) {
        System.out.println(new W().count+" "+new W().count);
    }
}

Expected output

c 1 c 2

Actual output

c c 1 2

Why?

Answer 1

The actual order of things executed by the JVM is as follows:

1. 1st W object is instantiated and its count property read.

   Here the first c is send to output.

2. 2nd W object is instantiated and its count property read.

   Here the second c is send to output.

3. The string argument for System.out.println() is built. ( == "1 2")

4. The string argument is sent to the output.

Thus the output results to c c 1 2.

Answer 2

In this line:

System.out.println(new W().count+" "+new W().count);

The instances of W are instantiated prior to the evaluation of the rest of the statement.

The order of operations is:

1. Instantiate first new W(), causing c to be printed
2. Evaluate first new W().count
3. Instantiate second new W(), causing c to be printed
4. Evaluate second new W().count
5. Concatenate the result and print.