Question

When I try to compile this:

public static Rand searchCount (int[] x)
{
    int a ;
    int b ;

    ...

    for (int l= 0; l<x.length; l++)
    {
        if (x[l] == 0)
        a++ ;
        else if (x[l] == 1)
        b++ ;
    }

    ...

}

I get these errors:

Rand.java:72: variable a might not have been initialized
                a++ ;
                ^
Rand.java:74: variable b might not have been initialized
                b++ ;
                ^
2 errors

It seems to me that I initialized them at the top of the method. What’s going wrong?

Answer 1

You declared them, but you didn’t initialize them. Initializing them is setting them equal to a value:

int a;        // This is a declaration
a = 0;        // This is an initialization
int b = 1;    // This is a declaration and initialization

You get the error because you haven’t initialized the variables, but you increment them (e.g., a++) in the for loop.

Java primitives have default values but as one user commented below

Their default value is zero when declared as class members. Local variables don’t have default values