Determining even/odd numbers (integers)?

It's not android specific, but a standard function would be:

boolean isOdd( int val ) { return (val & 0x01) != 0; }

Many compilers convert modulo (%) operations to their bitwise counterpart automatically, but this method is also compatible with older compilers.

if ((n % 2) == 0) {
    // number is even
}

else {
    // number is odd
}