Multidimensional Arrays lengths in Java

Question

How to find the lengths of a multidimensional array with non equal indices?

For example, I have int[][] pathList = new int[6][4]

Without actuall

Answer 1

This is for a 3 dimensional array.

 int x[][][]=new int[5][8][10];
        System.out.println(x.length+" "+x[1].length+" "+x[0][1].length);

OUTPUT : 5 8 10

Answer 2

You can find '4' by using pathlist[i].length

Please rectify me if I am wrong as I am a novice and would help me in understanding Java better. The following code may help you in understanding.

public class Main {

    public static void main(String[] args) {


        int num[][] = new int[1][3];
        for (int i = 0; i < num.length; i++) {
            for (int j = 0; j < num[i].length; j++) {
                num[i][j] = 10;
                System.out.println("num [" + i + "] [" + j + "] = " + num[i][j]);
            }
        }
    }
}

Answer 3

Java has "jagged" multidimensional arrays, which means that each "row" in your two-dimensional array can have a different number of components. If you can assume that each row has the same number of components, use:

pathList[0].length;

Otherwise, you will have to iterate:

int maxRowLength = 0;
for (int i = 0; i < pathList.length; i++) {
    if (maxRowLength < pathList[i].length) {
        maxRowLength = pathList[i].length;
    }
}

Answer 4

In java we can define array of arrays which we call multi dimensional arrays.By array of arrays we mean that a single elment of our array is again an array (in java can be of multiple length).To find length of multi array having all subarray of same size,we can use:

int[][]a=new int[3][3];//let a[][] be my array
a.length will work.   //a is an object of proxy class and length is its property.

However,if you have subarrays of different sizes then you have to iterate it.

for(i=0;i<a.length;i++)
        int cur_size=a[i].length;

Answer 5

This will give you the length of the array at index i

pathList[i].length

It's important to note that unlike C or C++, the length of the elements of a two-dimensional array in Java need not be equal. For example, when pathList is instantiated equal to new int[6][], it can hold 6 int [] instances, each of which can be a different length.

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So when you create arrays the way you've shown in your question, you may as well do

 pathList[0].length

since you know that they all have the same length. In the other cases, you need to define, specific to your application exactly what the length of the second dimension means - it might be the maximum of the lengths all the elements, or perhaps the minimum. In most cases, you'll need to iterate over all elements and read their lengths to make a decision:

for(int i = 0; i < pathList.length; i++)
{
    int currLen = pathList[i].length;
}

Answer 6

For 2 D array :-

int x[][] = new int[6][12];
System.out.println(x.length + " " + x[1].length);

OUTPUT : 6 12