（JAVA）选项卡声明错误（在构造函数中使用类选项卡）

Question

I have a problem with a declaration of tab in Java, I'm declaring a new array tab in a class and I want to use it in the constructor and then return the constructor's tab in a method, but I have problem with the tab declaration ( compiler error ). What's wrong here ?

class pascal5 {
int[] tab;
int prev1, prev2;

pascal5(int n) {
    tab[]=new int[n+1];

    for(int i = 0; i <= n; i++) {
        for(int k = 0; k <= i; k++) {
            if (k == 0) {
                tab[k] = 1;
                prev2 = 1;
            } else {
                prev1 = tab[k-1] + tab[k];
                tab[k-1] = prev2;
                prev2 = prev1;
            }
        }
    }
}

   int wspolczynnik(int m) {
   return tab[m];
  }

Answer 1

you cannot use the brackets [] after declaring the array just use the name of array to assign a new Array

Replace this line tab[]=new int[n+1]; with tab = new int[n+1];

Answer 2

Your problem is with the statement:

tab[] = new int[n+1];

Instead, use:

tab = new int[n+1];

Answer 3

You are initialising your tab in wrong way inside the constructor,

Do it like this,

tab = new int[n+1];

For more info on Arrays, check here .

You can also declare your array like this:

int[] tab = new int[3];
int[] tab = {1,2,3};
int[] tab = new int[]{1,2,3};