final?

[matt271]

from my understanding, in java, final means constant.

like:

Java:

public static final String eh = "the";

but i tried to created a nested thread like this:

Java:

public void test(final String eh) {         new Thread() {             @Override             public void run() {                 System.out.println(eh);             }         }.start();     }

and netbeans told me to "make String eh final" so i am curious what this final means in this case. how can it be a constant if its an argument?

public void test(final String eh) {

ty

[Vermette]

Declaring method parameters to be final is a defensive programming strategy to help avoid unintended side effects. If the method has no need to modify a passed value, the final keyword prevents you from doing so.

Java:

//changing final values is illegal at compile time public int foo(final int a) {     //....   return ++a; } //Changing final references is also illegal public void bar(final SomeObj A) {   SomeObj B = new SomeObj();   //....   A = B; } //however, manipulating objects is still legal public void baz(final SomeObj B) {   int x = 42;   //....   B.y = x; }

Another thing to keep in mind is that using final does not alter the method signature when resolving a call, so foo(int a) and foo(final int a) are identical from an overloading perspective.

[DemonWasp]

It's also worthy of note that in Java, the String class is final itself. That means that even though it's technically an object, you can't change it once it's created - all the mutator methods create a new String.

[matt271]

ok i get it. ty ty