public static void main(String[] args){
int x = 4;
int y = 5;
int z;
z = A(x,y);
System.out.println("z1=" + z);
z = B(A(x,y),y);
System.out.println("z2=" + z);
z = A(++x,B(x,y));
System.out.println("z3=" + z);
} // end main
private static int A(int a,int b){
int i = b - a;
if (b < 3) i-=b;
return i;
} // end A
private static int B(int c,int d){
int j = c + d;
if (c > 3) j += d;
return j;
} // end B
}// end class

First we declare the parameters...

x=4
y=5
z=0


Then off we go:

------

z=A(4,5); <---- Call to function A();
i=5-4;
if (5<3) ...do nothing.
i=1;

display ("1");

------

z=B(1,5); <---- Call to function B(); for how I got the first parameter, see right above ^_^
j = 1 + 5;
if (1>3) ...nope, do nothing.
j=6

display ("6");


------


Third call - break it down to A(++param1, functB());

functB() --V
B(5,5); <----- first parameter has already been incremented (++4 = 5)!!!
j = 5+5;
if (5>3) then, yes, j = 10 + 5;
return 15;


z = A(5, 15);
i = 15-5;
if (10<3) ...nope, do nothing
i=10;

display ("10");


Final output:
z1=1
z2=6
z3=10

Let's write some code:

int var = 4;
System.out.println("1: "+var);
System.out.println("2: "+ ++var);
System.out.println("3: "+var);

System.out.println("---");

var = 4;
System.out.println("1: "+var);
System.out.println("2: "+ var++);
System.out.println("3: "+var);



And let's execute all of that - and read the output:

1: 4
2: 5 <---- var has already been rewritten!
3: 5
---
1: 4
2: 4 <---- not yet rewritten - that will happen AFTER this line of code is executed.
3: 5

See the difference? It all depends on WHEN the incremented value is written back to the variable.