编译程序时出现错误（线程“ main”中的异常java.lang.ArrayIndexOutOfBoundsException）

Question

Hi Everyone i was practicing Java Language. And i faced this problem. I'm beginner in this language. i'm studying it, in my collage. Here is the question.

"Create A java program that will derive the sum of a number. For example, an input of 5 will produce(1+2+3+4+5=15)"

i know the answer but i was trying to solve it in another way.

    public class Sum11 {
    static int i;

     static int[] S = new int[5];
     static int  j;
     static int Sum = 0;

    Sum11(int i,int S[],int j){
    this.S=S;
    this.i=i;
    this.j=j;

    }


    public static void main(String[] args){
        Scanner s1 = new Scanner(System.in);
        for(i=1;i<=5;i++){
            System.out.println("Enter FIve Number");
           S[i]= s1.nextInt();
        }
        for(int num : S){
            Sum = Sum+num;
        }
        System.out.println("The Result IS: "+Sum);
    }

}

Answer 1

Array indices in java start in 0, so your input loop should be :

System.out.println("Enter Five Numbers");
for(i=0;i<S.length;i++) {
    S[i]= s1.nextInt();
}

Answer 2

The problem with the array index S[5] in an array of 5 elements is one problem. Another problem is that I think you misunderstood the exercise.

"Create A java program that will derive the sum of a number. For example, an input of 5 will produce(1+2+3+4+5=15)"

It asks for "the of a number ", not "number s ", and it seems the input is a single number, for example the number 5.

The solution of that using a loop could be for example:

int num = scanner.nextInt();
int sum = 0;
for (int i = 1; i <= num; ++i) {
    sum += i;
}

There is also a math solution with a simple formula:

int num = scanner.nextInt();
int sum = num * (num + 1) / 2;

Answer 3

The array S is initialized as:

 static int[] S = new int[5]; 

And then in the main function you loop from 1 until 5:

 for(i=1;i<=5;i++){ System.out.println("Enter FIve Number"); S[i]= s1.nextInt(); } 

Attempting to set values at indexes 1, 2, 3, 4, 5. But in Java array's are 0-based, so the indexes in this example should be 0, 1, 2, 3, 4.

You were prone to such problems because S is declared and initialized so far away from where it's actually used. And you don't actually need it at all. You could calculate the sum on the fly, without fumbling with an array:

int sum = 0;
for(i=1;i<=5;i++){
    System.out.println("Enter FIve Number");
    sum += s1.nextInt();
}

Answer 4

Java数组的起始索引为0。您必须执行以下操作：

for(i=0;i<5;i++){