[Solved] why outer for loop variable can’t be used in inner for loop

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As defined in JLS, the first “part” of the for loop declaration, ForInit, is a list of statement expressions or a local variable declaration; j isn’t a statement expression (an assignment; a pre/post increment/decrement; a method invocation; a new class initialization) or a local variable declaration, so it’s invalid syntax.

Depending upon what you are trying to do, you can just omit it:

for (; j < 8; j++)

Note that all of the three “parts” of the for loop are optional: for instance, this is fine:

for (;;) {
}

(It’s just an infinite loop)

solved why outer for loop variable can’t be used in inner for loop