Interesting JDK 12 features to watch out for.

With the new 6 months Java release cycle, you should expect cool features to get to developers at a faster rate. I have seen some cools features which you could expect to see in the JDK 12 release next year. You can get the Open JDK 12 early access build and try these preview features out.

Switch expressions

For example, you have an enum for the days of the week and you want to use switch statement to return the number of letters in the string. There are better ways to do this but we are going to use Switch statements to demonstrate this.

Here is the enum:

enum DayOfWeek{
MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
}

With what we know in Java this would probably be the solution:

      int numLetters;
        switch(day){
            case MONDAY: case FRIDAY: case SUNDAY:
                numLetters=6;
                break;
            case TUESDAY:
                numLetters=7;
                break;
            case THURSDAY: case SATURDAY:
                numLetters=9;
                break;
            case WEDNESDAY:
                numLetters=10;
                break;
            default:
                throw new NoSuchDayException(day);

        }

This could really trigger some bugs as it could make the code hard to maintain.
With Switch Expressions, you could write the Switch as an expression. No default is needed in the Switch statement.

Here is how the code would look like:

int numLetters=switch(day)
        {
            case MONDAY, FRIDAY, SUNDAY -> 6;
            case TUESDAY -> 7;
            case THURSDAY, SATURDAY -> 8;
            case WEDNESDAY -> 9;
        };

Records

We all know our POJOs (plain old Java object), they come with a lot of boilerplate code, for example here is a classic POJO:

class Point {
    double x;
    double y;

    Point(double x, double y) {
        this.x = x;
        this.y = y;
    }

    public void setX(double x) {
        this.x = x;
    }

    public double getX() {
        return x;
    }

    public void setY(double y) {
        this.y = y;
    }

    public double getY() {
        return y;
    }

    @Override
    public int hashCode() {
        return super.hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        return super.equals(obj);
    }


    @Override
    public String toString() {
        return super.toString();
    }
}

Well, Records (currently not targeted to JDK 12 at the time of this writing) replace all that POJO code with just one line:

 record Point(double x, double y);

There are other cool features to expect in JDK 12 and beyond, I personally appreciate the fact that the Java community is responding and aiming to move Java forward.

In case you are interested in learning way more you could check out this video:

Blog

Interesting JDK 12 features to watch out for.

Lemuel Ogbunude

Switch expressions

Records

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