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Interesting JDK 12 Features to Watch Out For - Please ignore as it was for testing.

sujit
Regular Visitor

Switch Expressions

For example, you have an enum for the days of the week and you want to use a 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 bugs, as it could make the code harder to maintain. With switch expressions, you can write the switch as an expression. No default is needed in the switch statement.

Here is what the code should look like:

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

 

Records (currently not targeted to JDK 12 at the time of this writing)

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 replaces all POJO code with just one line:

 
record Point(double x, double y);
 

 

There are other cool features that you could expect in JDK 12 and beyond. I, personally, appreciate that the Java community is evolving and aiming to move Java forward. With the new 6 months release cycle, we should expect cool features to get out faster, which is cool!

 

I suggest you check this video out: https://www.youtube.com/watch?v=nKJbDYRsO0s

Version history
Last update:
March 2019
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