// Comma used to separate a list of variable declarations

int a=20, b=30, c=80;



// Comma used to separate a list of values assigned to an array

int[] d = { 20, 60, 80 };



// Comma used to separate a list of parameters passed to a function

line(a, b, c, b);

line(d[0], d[1], d[2], d[1]);