i need to complete the method moveRocketBy(). marked in bold. The method should move the rocket upwards by the amount given by the method's argument. In other words, the method needs to change the y-positions of the parts of the rocket.

To do this, first set the nose position, and then set the body and jet positions relative to the nose and body, respectively. You must make use of the methods you wrote for part a., as well as other methods.

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public class Rocket { private Triangle nose; // represents the rocket's nose cone private Square body; // represents the rocket's body private Circle jet; // represents the blast from the rocket's engine

/** * Constructor for objects of class Rocket */ public Rocket(Triangle t, Square s, Circle c) { //first, we store references to the workspace shape objects this.nose = t; this.body = s; this.jet = c;

//sets the initial positions of the nose. //The other parts need to be set relative to these positions. this.nose.setXPos(50); this.nose.setYPos(300);

//sets the body relative to the nose, using the helper methods this.body.setXPos(getBodyXPos()); this.body.setYPos(getBodyYPos());

//The jet is invisible to begin with, because it uses //the background colour of WHITE, but you can use BLACK //to help you see it while testing this.jet.setColour(OUColour.WHITE); this.jet.setDiameter(10);

//sets the jet position relative to the body, using the helper methods this.jet.setXPos(getJetXPos()); this.jet.setYPos(getJetYPos()); }

private int getBodyXPos() { //to be written in Q1(a)(i) return this.body.getXPos(); }

private int getBodyYPos() { //to be written in Q1(a)(ii) return this.body.getYPos(); } private int getJetXPos() { //to be written in Q1(a)(iii) return this.jet.getXPos(); }

private int getJetYPos() { //to be written in Q1(a)(iv) return this.jet.getYPos(); }

/** * Moves the nose of the receiver * by anInt units. * Moves other rocket components relative to the * position of the nose. */ public void moveRocketBy(int anInt) { //to be written in Q1(b) }

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