Question

Use java, you are to create a brand new base class called NSpaceCoordinate in a file called nspace/NSpaceCoordinate.java. It has the following requirements:

1. It must have a single private field, an ArrayList specialized (using the generics feature discussed in the lecture) to holding values of type double (actually, Double).

2. Provide a constructor that takes a double[] and sets up the ArrayList field to have those same values.

3. Provide a method called getNthCoordinate(int i).

4. Implement the Comparable interface and set up the compareTo method to implement a dictionary ordering. Example: (1, -2.5, -3) < (1, -2.5, 9) (because -3 < 9) (1, -2.5) < (1, -2.5, 9) (because there is no third coordinate in the value on the left hand side)

5. Implement the magnitude and toString methods. toString should print out coordinates by enclosing them in parentheses and with components separated by commas. Next, copy over the twospace/TwoSpaceCoordinate.java, twospace/Complex.java, twospace/PolarComplex.java and twospace/StandardComplex.java files from the Lecture 11 demo. Change twospace.TwoSpaceCoordinate so that it extends nspace.NSpaceCoordinate. Make changes to TwoSpaceCoordinate so that it makes "maximum use" of the NSpaceCoordinate base class. The public interface for TwoSpaceCoordinate should not change. Basically, the TwoSpaceCoordinate file should get a lot shorter as you eliminate redundant/unnecessary code inside the implementation. Do not change any of the *Complex.java files. Finally, write a test driver (app/Main.java) and have its main method do the following:

1. Create an ArrayList containing 3 StandardComplex objects whose values are taken from the command line parameters. For example, calling your app.Main driver as follows should create an array with values 2+i, 2-i, and 2: java app.Main 2 1 2 -1 2 0

2. Use Collections.sort to sort the array.

3. For each element in the array (after sorting), print a single line containing the element's value (you can rely on StandardComplex's normal toString method) and the element's absolute value (call the abs() method), separated by a comma. So in this example you should be printing something similar to the following (might have different spacing/precision but in the same order): 2-i,2.23

2,2

2+i,2.23

mentioned class in step 5:

1.

package twospace;

public interface Complex {
public double re();
public double im();
public double r();
public double th();

public Complex plus(Complex b);
public Complex minus(Complex b);
public Complex times(Complex b);
public double abs();
}

2.

package twospace;

public class PolarComplex implements Complex {
public double r;
public double th;

public PolarComplex(double r, double th) {
this.r = r;
this.th = th;
}

public double re() {
return r * Math.cos(th);
}

public double im() {
return r * Math.sin(th);
}

public double r() {
return r;
}

public double th() {
return th;
}

// return a new Complex object whose value is (this + b)
public Complex plus(Complex b) {
double real = this.re() + b.re();
double imag = this.im() + b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this - b)
public Complex minus(Complex b) {
Complex a = this;
double real = a.re() - b.re();
double imag = a.im() - b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this * b)
public Complex times(Complex b) {
return new PolarComplex(this.r() * b.r(), this.th() + b.th());
}

public double abs() {
return Math.abs(r);
}

public String toString() {
double im = this.im();
double re = this.re();
if (im == 0) return re + "";
if (re == 0) return im + "i";
if (im < 0) return re + " - " + (-im) + "i";
return re + " + " + im + "i";
}
}

3.

package twospace;

public class StandardComplex extends TwoSpaceCoordinate implements Complex {
// private final double real;
// private final double imag;
public StandardComplex(double real, double imag) {
// this.real=real;
// this.imag=imag;
super(real, imag);
}

// return a string representation of the invoking Complex object
public String toString() {
if (this.im() == 0) return this.re() + "";
if (this.re() == 0) return this.im() + "i";
if (this.im() < 0) return this.re() + " - " + (-this.im()) + "i";
return this.re() + " + " + this.im() + "i";
}

// return abs/modulus/magnitude
public double abs() {
return magnitude();
}

public double r() {
return abs();
}

public double th() {
return Math.atan2(this.im(), this.re());
}

// return a new Complex object whose value is (this + b)
public Complex plus(Complex b) {
double real = this.re() + b.re();
double imag = this.im() + b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this - b)
public Complex minus(Complex b) {
Complex a = this;
double real = a.re() - b.re();
double imag = a.im() - b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this * b)
public Complex times(Complex b) {
Complex a = this;
double real = a.re() * b.re() - a.im() * b.im();
double imag = a.re() * b.im() + a.im() * b.re();
return new StandardComplex(real, imag);
}

// return the real or imaginary part
public double re() { return getFirstCoordinate(); }
public double im() { return getSecondCoordinate(); }

public boolean equals(Object x) {
if (x == null || !(x instanceof Complex)) return false;
Complex that = (Complex) x;
return (this.re() == that.re()) && (this.im() == that.im());
}
}

4.

package twospace;

public class TwoSpaceCoordinate {
private final double first;
private final double second;

public TwoSpaceCoordinate(double first, double second) {
this.first = first;
this.second = second;
}

public final double getFirstCoordinate() {
return this.first;
}

public final double getSecondCoordinate() {
return this.second;
}

public final double magnitude() {
return Math.sqrt(this.first * this.first + this.second * this.second);
}
}

Answer 1

package twospace;

public interface Complex {
public double re();
public double im();
public double r();
public double th();

public Complex plus(Complex b);
public Complex minus(Complex b);
public Complex times(Complex b);
public double abs();
}

2.

package twospace;

public class PolarComplex implements Complex {
public double r;
public double th;

public PolarComplex(double r, double th) {
this.r = r;
this.th = th;
}

public double re() {
return r * Math.cos(th);
}

public double im() {
return r * Math.sin(th);
}

public double r() {
return r;
}

public double th() {
return th;
}

// return a new Complex object whose value is (this + b)
public Complex plus(Complex b) {
double real = this.re() + b.re();
double imag = this.im() + b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this - b)
public Complex minus(Complex b) {
Complex a = this;
double real = a.re() - b.re();
double imag = a.im() - b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this * b)
public Complex times(Complex b) {
return new PolarComplex(this.r() * b.r(), this.th() + b.th());
}

public double abs() {
return Math.abs(r);
}

public String toString() {
double im = this.im();
double re = this.re();
if (im == 0) return re + "";
if (re == 0) return im + "i";
if (im < 0) return re + " - " + (-im) + "i";
return re + " + " + im + "i";
}
}

3.

package twospace;

public class StandardComplex extends TwoSpaceCoordinate implements Complex {
// private final double real;
// private final double imag;
public StandardComplex(double real, double imag) {
// this.real=real;
// this.imag=imag;
super(real, imag);
}

// return a string representation of the invoking Complex object
public String toString() {
if (this.im() == 0) return this.re() + "";
if (this.re() == 0) return this.im() + "i";
if (this.im() < 0) return this.re() + " - " + (-this.im()) + "i";
return this.re() + " + " + this.im() + "i";
}

// return abs/modulus/magnitude
public double abs() {
return magnitude();
}

public double r() {
return abs();
}

public double th() {
return Math.atan2(this.im(), this.re());
}

// return a new Complex object whose value is (this + b)
public Complex plus(Complex b) {
double real = this.re() + b.re();
double imag = this.im() + b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this - b)
public Complex minus(Complex b) {
Complex a = this;
double real = a.re() - b.re();
double imag = a.im() - b.im();
return new StandardComplex(real, imag);
}

// return a new Complex object whose value is (this * b)
public Complex times(Complex b) {
Complex a = this;
double real = a.re() * b.re() - a.im() * b.im();
double imag = a.re() * b.im() + a.im() * b.re();
return new StandardComplex(real, imag);
}

// return the real or imaginary part
public double re() { return getFirstCoordinate(); }
public double im() { return getSecondCoordinate(); }

public boolean equals(Object x) {
if (x == null || !(x instanceof Complex)) return false;
Complex that = (Complex) x;
return (this.re() == that.re()) && (this.im() == that.im());
}
}

4.

package twospace;

public class TwoSpaceCoordinate {
private final double first;
private final double second;

public TwoSpaceCoordinate(double first, double second) {
this.first = first;
this.second = second;
}

public final double getFirstCoordinate() {
return this.first;
}

public final double getSecondCoordinate() {
return this.second;
}

public final double magnitude() {
return Math.sqrt(this.first * this.first + this.second * this.second);
}
}