打印多维数组Java

Question

I just wanna print my empty array by for loops.

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 10

What is wrong?

int NYEARS = 5;
int NRATES = 3;

double[][] balancee = new double[NYEARS][NRATES];
for (int i = 0; i < NYEARS; i++) {
    for (int j = 0; j < NRATES; j++) {
        System.out.print(balance[NYEARS][NRATES] + " ");
        System.out.println();
    }
}

Answer 1

You should be using the loop indices to access the array elements, not the array dimensions:

for (int i = 0; i < NYEARS; i++) {
    for (int j = 0; j < NRATES; j++) {
        System.out.print(balance[i][j] + " ");
        System.out.println();
    }
}

Answer 2

Your solution will cause java.lang.ArrayIndexOutOfBoundsException: 5 you have also a typo balance instead you mean balancee :

So Instead you have to use balancee.length and balancee[i].length and not balance[NYEARS][NRATES] , so you have to use balancee[i][j] like this :

for (int i = 0; i < balancee.length; i++) {
    for (int j = 0; j < balancee[i].length; j++) {
        System.out.print(balancee[i][j] + " ");
        System.out.println();
    }
}

Answer 3

I would prefer generally foreach when I don't need making arithmetic operations with their indices

for (double[] x : balancee) { 
    for (double y : x) { 
        System.out.print(y + " ");
 }        
    System.out.println(); 
 }

More importantly, I hope you get why you cannot use balance[NYEARS][NRATES] .

Answer 4

Just use the built-in Arrays.deepToString()

int[][] foo = { null, {}, { 1 }, { 2, 3 } };
System.out.println(Arrays.deepToString(foo));

Output

[null, [], [1], [2, 3]]

Answer 5

int NYEARS = 5; //This is the size
int NRATES = 3; //This is the size

double[][] balancee = new double[NYEARS][NRATES]; //<-- balancee vs balance



for (int i = 0; i < NYEARS; i++) {
for (int j = 0; j < NRATES; j++) {
    System.out.print(balance[NYEARS][NRATES] + " "); //<-- use i and j instead of size. 
    System.out.println();
    }
}