Differences to Scratch

Probably the most noticeable differences to Scratch are the following:

• The coordinated start in the top left hand side corner and not in the center.
• There is not wait-block on a Sprite-level, you need to use Timers.

If you want to achieve something like this inside a Sprite:

when green flag clicked
forever
next costume
wait (1) seconds

You can use a timer.

public class Cat extends Sprite {
    // executes 60-times a second, if the sprite is added to a stage.
    public void run() {
        if (this.getTimer().everyMillis(1000)) {
            this.nextCostume();
        }
    }
}

• There is no Sprite library, you have to search the internet.
• There is no Sound library, you have to search the internet.
• There are no built-in editors, you have to use external tools like GIMP, Inkscape, Audacity and so on.
• If you want to share your project with others, you have to used external sharing platforms like Nextcloud, iCloud, Dropbox or better a code sharing platform like GitHub.
• You can not use a forever loop. This will halt you program.

If you want to achieve something like this inside a Sprite:

when green flag clicked
forever
move (10) steps

You can use the run-method of the Sprite-class.

public class Cat extends Sprite {
    // executes 60-times a second, if the sprite is added to a stage.
    public void run() {
        this.move(10);
    }
}

• If you want to have a variable for all sprites, you have to use a static attribute. Static attributes are available across all objects.

public class Cat extends Sprite {
    public static int hitCounter = 1;
}
 
public class MyProgram {
    public MyProgram() {
        Cat.hitCounter += 1;
    }
}