Exception in thread "main"

Question

I don't know why program will be e [ab] [ac] where an error. I am a beginner, strives for the answer
This is the code：
public class test
{
public static void main(String[] args) {
System.out.print("this is a test java ,it can realize some intersting function ,and so on. "+"\n");
int A=0;
int B=0;
int[] maths;
maths=new int [4];
int[][]e=new int [4][4];
int ab=-1;
int ac=-1;
for(int a=0;a<=4;a++) {
ab++;
for(int c=0;c<=4;c++){
B++;
ac++;
e[ab][ac]=B;
System.out.println(e[ab][ac]);
//there，it is wrong.
}
}
if(A<10){
for(int a=0;a<=5;a++){
A++;
System.out.println("the nember is "+A);
}
}
}
}

Answer 1

Fix two places
1. Array size is 4, so for loop should start from 0 to 3. The code is from 0 to 4.
2. After inner loop(loop c), variable "ac" value need to be reset to -1. So add line ac = -1;

Answer 2

oh, thank you, I've been solved:-)

Answer 3

first, make sure your variables are all the same case every time you use them. Next on your last line of code tou have +A, try changing that to ++A.

Answer 4

wow i didnt know that first one, u thought you had to keep it between 0 and you choice of number. :) cool good to know