For Each Loop Editing Original 2D Array

Question

In the for each loop, the output is 6. However, I thought that the output would be 0 since, at least for one dimensional arrays, for each loops only traverse arrays. How is "g" being edited if "f" is only a local variable in the loop?

int[][] g = new int[7][7];

for(int[] f : g) {
    for(int h = 0; h < f.length; h++)
        f[h] = 6;
}

System.out.println(g[4][6]);

An `int[]` is a reference type, so your `int[][]` has elements that are of reference type. Thus you can modify the value. — Elliott Frisch, Apr 01 '16 at 03:04

score 2 · Accepted Answer · edited May 23 '17 at 11:59

Even though Java is pass-by-value, if the values you pass are references to mutable data types, they can be mutated.

As you know, f is the value that you're iterating over in an enhanced-for loop, but it represents each element contained inside of your two-dimensional array g.

In this scenario, it's your int[] that is mutable. You are actively editing the values in your two-dimensional array to another value entirely.

For Each Loop Editing Original 2D Array

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