What's the syntax for mod in java

Instead of the modulo operator, which has slightly different semantics, for non-negative integers, you can use the remainder operator %. For your exact example:

if ((a % 2) == 0)
{
    isEven = true;
}
else
{
    isEven = false;
}

This can be simplified to a one-liner:

isEven = (a % 2) == 0;

Here is the representation of your pseudo-code in minimal Java code;

boolean isEven = a % 2 == 0;

I'll now break it down into its components. The modulus operator in Java is the percent character (%). Therefore taking an int % int returns another int. The double equals (==) operator is used to compare values, such as a pair of ints and returns a boolean. This is then assigned to the boolean variable 'isEven'. Based on operator precedence the modulus will be evaluated before the comparison.

Since everyone else already gave the answer, I'll add a bit of additional context. % the "modulus" operator is actually performing the remainder operation. The difference between mod and rem is subtle, but important.

(-1 mod 2) would normally give 1. More specifically given two integers, X and Y, the operation (X mod Y) tends to return a value in the range [0, Y). Said differently, the modulus of X and Y is always greater than or equal to zero, and less than Y.

Performing the same operation with the "%" or rem operator maintains the sign of the X value. If X is negative you get a result in the range (-Y, 0]. If X is positive you get a result in the range [0, Y).

Often this subtle distinction doesn't matter. Going back to your code question, though, there are multiple ways of solving for "evenness".

The first approach is good for beginners, because it is especially verbose.

// Option 1: Clearest way for beginners
boolean isEven;
if ((a % 2) == 0)
{
  isEven = true
}
else
{
  isEven = false
}

The second approach takes better advantage of the language, and leads to more succinct code. (Don't forget that the == operator returns a boolean.)

// Option 2: Clear, succinct, code
boolean isEven = ((a % 2) == 0);

The third approach is here for completeness, and uses the ternary operator. Although the ternary operator is often very useful, in this case I consider the second approach superior.

// Option 3: Ternary operator
boolean isEven = ((a % 2) == 0) ? true : false;

The fourth and final approach is to use knowledge of the binary representation of integers. If the least significant bit is 0 then the number is even. This can be checked using the bitwise-and operator (&). While this approach is the fastest (you are doing simple bit masking instead of division), it is perhaps a little advanced/complicated for a beginner.

// Option 4: Bitwise-and
boolean isEven = ((a & 1) == 0);

Here I used the bitwise-and operator, and represented it in the succinct form shown in option 2. Rewriting it in Option 1's form (and alternatively Option 3's) is left as an exercise to the reader. ;)

Hope that helps.