Thank you for the answer 
I would have something like this then:
static class MyVector {
final PApplet pa;
float v1, v2;
MyVector(final PApplet pa, float v1, float v2) {
this.v1 = v1;
this.v2 = v2;
this.pa = pa;
}
public static MyVector createUnitVector(final PApplet pa) {
return new MyVector(pa, 1, 0);
}
public static MyVector createRandomVector(final PApplet pa) {
return new MyVector(pa, pa.random(1), pa.random(1));
}
public void randomize() {
v1 = pa.random(1);
v2 = pa.random(1);
}
}