How do i use temp variable?

Answer 1

int i = 14; // some variable

int temp = i;
// A variable used only to store something for a short period of time

The question is sort of to vague, you use the temp variable the same way you use a variable. Depends on what it's purpose is in the program.

Answer 2

int i, j, k; <<declared i,j,k to a data type int

i = 2; <<initialized one of the declared variables

System.out.println(i);

Answer 3

declare a variable,
name it temp (or anything else)