Question

The following code must be written and run with no errors in java eclipse

Description of the code to be written:

A resistor is an electronic part colour-coded with three coloured bands to indicate its resistance value. This program returns the resistance of a Resistor object instantiated with three Strings, representing the three colour bands of a real resistor.

Start by creating an abstract class 'AbstractResistor' that implements the Comparable interface. This class should have the following three private methods:

-firstBand: String
-secondBand: String
-thirdBand: String

along with public setters and getters for each String.

Now add a concrete class, Resistor, that extends from AbstractResistor. This class should have three public methods:

+getValue(colour: String): int
+getResistance(): int
+compareTo(obj:Object): int

along with a Resistor constructor that takes, and sets, the three String parameters corresponding to the three bands indicated above.

The first of the three methods, getValue(), takes in a single String as its parameter. The String will always be one of the following Strings, and you code must return the integer next to it:
   "Black"   0
   "Brown"   1
   "Red"   2
   "Orange"   3
   "Yellow"   4
   "Green"   5
   "Blue"   6
   "Violet"   7
   "Grey"   8
   "White"   9

To implement this, you must declare an ArrayList of type String and load it with the 10 Strings listed; the index of the String should return the value associated with the String passed as a parameter. Thus getValue("Red") returns '2'.

The second method, getResistance(), returns the resistance of the current Resistor object based on the colour of the three bands. The equation for the resistance is:

(firstBandValue * 10 + secondBandValue) * (10 ^ (thirdBandValue))

where the band values are just the integer values returned by getValue() for the colour String input. Thus for a Resistor instantiated with the three Strings "Brown", "Red", "Red", the value returned by getResistance() would be :

(1 (Brown) * 10 + 2 (Red)) * (100) (i.e. 10 raised to the power of "Red" = 2) = 1200.

You can use Math.power(10, getValue(getThirdBand())) for the last part of the calculation.

Finally, the third method, compareTo(), must return a number less than, greater than, or equal to 0, suitable for use in searching and sorting. (You'll want to use the getResistance() method to do this correctly.)

Now add the following third class to your program and run it.

import java.util.ArrayList;
import java.util.Collections;

public class ResistorTester {
   public static void main(String[] args) {
   ArrayList<Resistor> arResistors = new ArrayList<>();
   arResistors.add(new Resistor("Grey", "Green", "Brown")) ;   //850
   arResistors.add(new Resistor("Red", "Black", "Black")) ;    //20
   arResistors.add(new Resistor("Brown", "Black", "Red")) ;    //1000
   Collections.sort(arResistors);
   for (Resistor r: arResistors) System.out.println(r.getResistance());
   }
}

You should see the numbers 20, 850, and 1000 output, in that order.

Answer 1

first we are use three private methods :

1] firstBand: String

2] secondBand: String

3] thirdBand: String

then we add concrete class and use three public methods

1] getValue(colour: String): int

2] getResistance(): int

3] compareTo(obj:Object): int

then we use 10 strings and interger number of this string

"Black"   0
   "Brown"   1
   "Red"   2
   "Orange"   3
   "Yellow"   4
   "Green"   5
   "Blue"   6
   "Violet"   7
   "Grey"   8
   "White"   9

then we use first public method

getValue("Red") returns '2';

the resistent equation is :

(firstBandValue * 10 + secondBandValue) * (10 ^ (thirdBandValue))

the Resistor instantiated with the three Strings "Brown", "Red", "Red", the value returned by getResistance() method

(1 (Brown) * 10 + 2 (Red)) * (100) (i.e. 10 raised to the power of "Red" = 2) = 1200

or

You can use Math.power(10, getValue(getThirdBand())) for the last part of the calculation

finally we use compareTo() method and return the number less than or greater than or equal to zero

import java.util.ArrayList;
import java.util.Collections;

public class ResistorTester

{
   public static void main(String[] args)

{
   ArrayList<Resistor> arResistors = new ArrayList<>();
   arResistors.add(new Resistor("Grey", "Green", "Brown")) ;   //850
   arResistors.add(new Resistor("Red", "Black", "Black")) ;    //20
   arResistors.add(new Resistor("Brown", "Black", "Red")) ;    //1000
   Collections.sort(arResistors);
   for (Resistor r: arResistors) System.out.println(r.getResistance());
   }
}

the output is

850

20

1000