Implement the Methods

package mobiles;

import java.awt.FontMetrics; import java.awt.Graphics2D; import java.awt.geom.AffineTransform; import java.awt.geom.Arc2D; import java.awt.geom.Line2D;

/** * A Mobile is either a Bob or Rod. * * A Bob is a Mobile consists of a weight hanging from a vertical wire. * * Here's a diagram, where W denotes a weight: * *

 * | * W * 

* * A Rod is a Mobile that consists of a horizontal rod that has one Mobile hanging from its left end and another Mobile * hanging from its right end. The rod is hanging from a vertical wire. The distance along the rod from the vertical * wire to the left end is called the left length, and the distance from the vertical wire to the right end is called * the right length. * * Here's a diagram: * *

 * _____|__________ * | | * L R * 

* * The left length is 5 and the right length is 10. L and R are the left and right Mobiles, respectively. */ public class Mobile { /** * True if the Mobile is a Bob; false if the Mobile is a Rod. */ private boolean isBob;

/** * If isBob is true, contains the weight of the Bob. */ private int weight;

/** * If isBob is false, contains the left length of the Rod. */ private int leftLength; /** * If isBob is false, contains the right length of the Rod. */ private int rightLength; /** * If isBob is false, contains the left Mobile of the Rod. */ private Mobile left; /** * If isBob is false, contains the right Mobile of the Rod. */ private Mobile right;

/** * Creates a Bob with the given weight. */ public Mobile (int weight) { this.isBob = true; this.weight = weight; }

/** * Creates a Rod of the given configuration. */ public Mobile (int leftLength, int rightLength, Mobile left, Mobile right) { this.isBob = false; this.leftLength = leftLength; this.left = left; this.rightLength = rightLength; this.right = right; }

// Formatting constants public final static double WIRE = 100; public final static double UNIT = 10; public final static double GAP = 2; public final static double TOP = 10; public final static int WIDTH = 1200; public final static int HEIGHT = 800;

/** * Draws this Mobile on g, beginning at point (x,y). */ public void display (Graphics2D g, double x, double y) { if (isBob) { FontMetrics fm = g.getFontMetrics(); int weightWidth = fm.stringWidth(weight + ""); int height = fm.getHeight(); g.draw(new Line2D.Double(x, y, x, y + WIRE)); g.draw(new Arc2D.Double(x - height, y + WIRE, 2 * height, 2 * height, 0, 360, Arc2D.OPEN)); g.drawString(weight + "", (float) (x - weightWidth / 2), (float) (y + WIRE + 1.25 * height)); }

else { // Get the widths of the labels FontMetrics fm = g.getFontMetrics(); int leftLabelWidth = fm.stringWidth(leftLength + ""); int rightLabelWidth = fm.stringWidth(rightLength + "");

// Show the mobile askew according to the degree of imbalance double leftTorque = left.weight() * leftLength; double rightTorque = right.weight() * rightLength; double theta = (rightTorque - leftTorque) / 100 * Math.PI / 6; theta = Math.min(theta, Math.PI / 6); theta = Math.max(theta, -Math.PI / 6);

// Draw the vertical wire g.draw(new Line2D.Double(x, y, x, y + WIRE));

// Compute the endpoints of the rod double leftX = x - Math.cos(theta) * (leftLength * UNIT); double leftY = y + WIRE - Math.sin(theta) * (leftLength * UNIT); double rightX = x + Math.cos(theta) * (rightLength * UNIT); double rightY = y + WIRE + Math.sin(theta) * (rightLength * UNIT);

// Compute the rotation AffineTransform at = new AffineTransform(); at.translate(x, y + WIRE); at.rotate(theta); g.setTransform(at);

// Draw the rod and display the text g.draw(new Line2D.Double(-leftLength * UNIT, 0, rightLength * UNIT, 0)); g.drawString(leftLength + "", (float) (-leftLength * UNIT / 2 - leftLabelWidth / 2), (float) -GAP); g.drawString(rightLength + "", (float) (rightLength * UNIT / 2 - rightLabelWidth / 2), (float) -GAP);

// Cancel the rotation at.setToRotation(0); g.setTransform(at);

// Display the left and right Mobiles left.display(g, leftX, leftY); right.display(g, rightX, rightY); } }

/** * Returns the total weight of all the Bobs in this Mobile. */ public int weight () {

IMPLEMENT METHOD return 0; }

/** * Reports whether all the Rods in this Mobile are completely horizontal. A Rod will be horizontal if the product of * its left length and the weight of its left Mobile equals the product of its right length and the weight of its * right Mobile. */ public boolean isBalanced () {

IMPLEMENT METHOD return false; }

/** * Returns the length of the longest path through this Mobile. There is one path for every Bob in the Mobile. Each * path leads from the top of the Mobile to a Bob, and its length is the number of Rods encountered along the way * plus one. */ public int depth () {

IMPLEMENT METHOD return 0; }

/** * Returns the number of Bobs contained in this Mobile. */ public int bobCount () {

IMPLEMENT METHOD return 0; }

/** * Returns the number of Rods contained in this Mobile. */ public int rodCount () {

IMPLEMENT METHOD return 0; }

/** * Returns the length of the longest Rod contained in this Mobile. If there are no Rods, returns zero. */ public int longestRod () {

IMPLEMENT METHOD return 0; }

/** * Returns the weight of the heaviest Bob contained in this Mobile. */ public int heaviestBob () {

IMPLEMENT METHOD return 0; } }