preincrement / postincrement in java

Question

Can someome help me to understand why:

int i=1;
int j=1;
int k=1;
int l=1;

System.out.println(i++ + i++);  
System.out.println(++j + ++j);  
System.out.pri         


        

Answer 1

As the name indicates, a post increment increments the value of the variable AFTER the variable has been processed (read) while the pre incrment increments the value BEFORE.

For i, that means that first i is incremented by 1, but read as 1, then incremented by 1 again (already being 2 now from the first increment), thus incremented to 3, but read as 2. This results in 1+2 = 3 and the value of i will be 3 as well...