How to fix 'cannot be resolved to a variable' error in Java

Question

I'm trying to implement a very simple sorting method that takes int array and sorts elements in ascending order, but I'm stuck with errors about variables

    public int[] sort1(int[] a){
        for (int i=0; i<a.length;i++)
            for(int j=i+1; j<a.length; j++)
                int min = a[i];
                if (a[j] < min) {
                    a[i] = a[j];
                    a[j] = min;
                    min = a[i];
                }
        return a;
    }

i cannot be resolved to a variable j cannot be resolved to a variable min cannot be resolved to a variable

I don't know why these errors come up and how to fix them.

You are missing a { after for(int j=i+1; j<a.length; j++) (and } later) — f1sh
– f1sh, Commented Sep 16, 2019 at 8:57
You definitely should always use braces, even if the body of the for or if statements contain a single statement. It'll save you from errors exactly like this. — MC Emperor
– MC Emperor, Commented Sep 16, 2019 at 9:02

Eran · Accepted Answer · 2019-09-16 08:56:18Z

8

You are missing curly braces:

public int[] sort1(int[] a){
    for (int i=0; i<a.length;i++) {
        for(int j=i+1; j<a.length; j++) {
            int min = a[i];
            if (a[j] < min) {
                a[i] = a[j];
                a[j] = min;
                min = a[i];
            }
        }
    }
    return a;
}

The inner loop has multiple statements, so you must enclose them with curly braces.

While the outer loop has only one statement, it is still advisable to enclose it with curly braces too.

answered Sep 16, 2019 at 8:56

Eran

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Comments

Michael · Accepted Answer · 2019-09-16 09:01:47Z

3

To complement Eran's answer, to the compiler this block

for (int j=i+1; j<a.length; j++)
    int min = a[i];
    if (a[j] < min) {
        a[i] = a[j];
        a[j] = min;
        min = a[i];
    }

is really something more like this

for (int j=i+1; j<a.length; j++) int min = a[i];
if (a[j] < min) {
    a[i] = a[j];
    a[j] = min;
    min = a[i];
}

Remember, Java is not a whitespace-aware language like Python, for example.

The first line here is also illegal. You can't perform assignment in a for-loop without braces - probably because there is no way to access the variable after the assignment since it is immediately out of scope.

answered Sep 16, 2019 at 9:01

Michael

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