8 More Concise try-with-resources Statements

If you already have a resource as a final or effectively final variable, you can use that variable in a try-with-resources statement without declaring a new variable. An "effectively final" variable is one whose value is never changed after it is initialized.

For example, you declared these two resources:

        // A final resource
        final Resource resource1 = new Resource("resource1");
        // An effectively final resource
        Resource resource2 = new Resource("resource2");

In Java SE 7 or 8, you would declare new variables, like this:

        try (Resource r1 = resource1;
             Resource r2 = resource2) {

In Java SE 9, you don’t need to declare r1 and r2:

// New and improved try-with-resources statement in Java SE 9
        try (resource1;
             resource2) {

There is a more complete description of the try-with-resources statement in The Java Tutorials (Java SE 8 and earlier).