CODEWITHSUNDEEP
javasyntax
Mike Mirabelli
Mike Mirabelli

Reputation: 410

What is the meaning of 'x = x + 2;' in this code snippet?

I am having trouble interpreting a piece of code within the class. The code is:

class PoolPuzzleOne {
    public static void main(String[] args) {
        int x = 0;
        while (x < 4) {
            System.out.print("a");
            if (x < 1) {
                System.out.print(" ");
            }
            System.out.print("n");

            if (x > 1) {
                System.out.print("oyster");
                x = x + 2;
            }
            if (x == 1) {
                System.out.print("noys");
            }
            if (x < 1) {
                System.out.print("oise");
            }
            System.out.println("");
            x = x + 1;
        }
    }
}

Result is:

% java PoolPuzzleOne
a noise
annoys
an oyster

I am confused as to what the x = x + 2; means after the "oyster" printout. Does this mean that this will text x in increments of '2' instead of the traditional increment of '1' for the particular test of x > 1?

Upvotes: 1

Views: 1631

Answers (2)

nick zoum
nick zoum

Reputation: 7295

When you use an operation like: x = x + 2; then you are adding that value to that variable.

In the case that x is a number (int, double, float, Integer, etc) then, regardless of how you order it the result will always be the same.

For example:

x = x + 2; is the same as x = 2 + x; and the same as x += 2;.

This is almost the same for strings.

If you have this code:

String text = "test";
text = text + 1;
System.out.println(text);

The output will be "test1"

For this code:

String text = "test";
text = text + "1";
System.out.println(text);

The output will also be "test1"

For this code:

String text = "test";
text += "1";
System.out.println(text);

The output will also be "test1"

But this code:

String text = "test";
text = "1" + test;
System.out.println(text);

Will output "1test"

Also, when you increment a number then instead of x = x + 1; you can use x++; or ++x; and when you decrement a number then instead of x = x - 1; you can use x--; or --x;

The difference between x++; and ++x; is when the addition will happen. x++ means that the addition will happen after the current operation whereas ++x means that the addition will happen before the current operation.

To explain what this means: if we have the statement System.out.println(x++); then x will be printed first and then will be incremented whereas if we use System.out.println(++x); the value of x will change and then it will be printed.

This means that for this code:

int x = 1;
int y = 1;
System.out.println(x++);
System.out.println(x);
System.out.println(y++);
System.out.println(y);

The output will be:

1
2
2
2

The same applies for the -- operation except that instead of adding 1 we subtract 1.

Upvotes: 1

LumberSzquatch
LumberSzquatch

Reputation: 1083

The x = x + 2 is used to terminate your while loop. If you notice your while loop only loops while x < 4 but in the case of printing "oyster" x must be at least greater than one. Nothing else seems to be printed out after oyster so, you add 2 to x to make the loop terminate.

Upvotes: 0

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