final_arguments.md

Final Arguments

Just like normal variable declarations, arguments can be marked final. This makes it so that they cannot be reassigned.

void eat(final String food) {
    System.out.println("I ate " + food);
}

void main() {
    eat("Welsh Rarebit");
}

If you try to reassign a final argument, Java will not accept your program.

void eat(final String food) {
    System.out.println("I ate " + food);
    // Will not work
    food = "toast";
    System.out.println(food);
}

void main() {
    eat("Welsh Rarebit");
}

This has the same use as regular final variables. If there are lots of lines of code where a variable might be reassigned, it can be useful to not have to read all that code to know that it does happen.¹

Footnotes

1. Adding final to all arguments can make it harder to read the code, simply because of visual noise. ↩