ParticleVector { public void set(double vectorX, double vectorY) { list.set(0, vectorX); list.set(1, vectorY); } ParticleVector();  ParticleVector(double vectorX, double vectorY); void add(ParticleVector vector); void set(double vectorX, double vectorY); Double getX(); Double getY(); @Override boolean equals(Object object); @Override int hashCode();  }
@Test public void testSet() { ParticleVector vector1 = new ParticleVector(); Assert.assertEquals(new ParticleVector(), vector1); vector1.set(10, 10); Assert.assertEquals(new ParticleVector(10, 10), vector1); }