JAVA Using to.String() methood to return a sting of a resistor network

Question

I'm a bit of a newbie to java and I'm having trouble with an assignment asking me to implement toString() method. The question asks that "write a method toString() which returns as a String the complete resistor network in the circuit and the resistance across the circuit. For example, the execution of the following piece of code:

SeriesCircuit s1 = new SeriesCircuit ( new Circuit( 2 ), new Circuit ( 3 ) );
ParallelCircuit p1 = new ParallelCircuit ( s1, new Circuit( 4 ) );
SeriesCircuit s2 = new SeriesCircuit ( p1, new Circuit( 1 ) );
ParallelCircuit p2 = new ParallelCircuit ( s2, new Circuit( 8 ) );
System.out.println( p2 + " = " + p2.getResistance() );

leads to the following output: ( ( ( ( 2.0 + 3.0 ) || 4.0 ) + 1.0 ) || 8.0 ) = 2.29702. Plus (+) stands for series while || represents parallel"

So far, ive made 2 subclasses one for SeriesCircuit

public class SeriesCircuit extends Circuit
{
      public Circuit a;
      public Circuit b;

    public double getResistance()
    {
        return resistance();
    }



    public SeriesCircuit(Circuit a, Circuit b)
    {
          this.a = a;
          this.b = b;
    }

    public double resistance() 
    {
           double rs1 =  a.resistance() + b.resistance();
           return rs1;
    }
}

Another for Parallel

public class ParallelCircuit extends Circuit
{

       public Circuit a;
       public Circuit b;

    public double getResistance()
    {
        return resistance();
    }



    public ParallelCircuit(Circuit a, Circuit b)
    {
          this.a = a;
          this.b = b;

    }

    public double resistance() 
    {
           double R1 = a.resistance();
           double R2 = b.resistance();
           double rp1 = 1.0 / (1.0 / R1  +  1.0 / R2);
           return rp1;
    }

}

While in the Circuit class, i don't have much going on at this time:

public class Circuit 
{


    public double resistance() 
    {
        return resistance();
    }


    public static void main(String[] args) 
    {


    }

}

Basically, I'm completely lost as to how I'm supposed to get the code the professor provided to execute and to have it output in a way he wants by using toString() method. Thanks.

Answer 1

In the class you need to write the toString() method for, try:

public String toString()
{
    String result = //build your string with whatever needs to be output
    return result;
}

As for the rest of your homework... you'll need to make more of an effort and come back with more specific questions.

Answer 2

Tips:

• Every class should have its own toString() method.
• A child class can often use the parent's toString() result as part of its own toString() result.
• A class that holds other objects by composition, such as an ArrayList or array of components, often uses the toString() results from the components it holds in its own toString(). This way a complex informative String can be returned via simple code.