In java please. Test code is:

public static void main(String[] args) { double r1 = 4; double r2 = 20; ArrayList amplifiers = new ArrayList();

amplifiers.add(new InvertingAmplifier(r1, r2)); amplifiers.add(new NoninvertingAmplifier(r1, r2)); amplifiers.add(new VdivAmplifier(r1, r2)); for (int i = 0; i Part (a) of the figure below shows a symbolic representation of an electric circuit known as the amplifier. The input to the amplifier is the voltage vi and the output is the voltage vo. The output of an amplifier is proportional to the input. The constant of proportionality is called the "gain" of the amplifier b) Inverting amplifier (a) Amplifier (d) Voltage divider (C) Noninverting R. R2 Parts (b), (c), and (d) show schematics of three specific amplifier types: the inverting amplifier, the noninverting amplifier, and the voltage divider amplifier. Each of these three amplifiers consists of two resistors and an operational amplifier. The value of the gain of each amplifier depends on the values of its resistances. In particular, the gain, g, of the inverting amplifier is given by g Similarly, the gains of the noninverting amplifier and the voltage divider amplifier are given by g = 1 and g = R +R-, r Write a Java program that represents the amplifier as a superclass and represents the inverting, noninverting, and voltage divider amplifiers as subclasses. Add the methods getGain and getDescription to the superclass. Each subclass should have a constructor with two arguments: the resistances R1 and R2 of the amplifier. The subclasses must override the getGain and getDescription methods of the superclass. Your classes should be compatible with the supplied AmplifiersApp main class. A sample output of running this application is here Inverting Amplifier: R1-4.0, R2-20.0 Gain: -5.0 Noninverting Amplifier: R1-4.0, R2-20.0 Gain: 6.0 Voltage Divider and Voltage Follower: R1-4.0, R2- 20.0 Gain: 0.8333333333333334