// Counter.java: a class representing a counter object
public class Counter{
    // the value of the counter
    // myValue is an integer variable giving the counter value
    private int myValue;

    // constructor -- used when a new counter is created (starts at 0)
    public Counter(){
         myValue = 0;
    }

    // constructor -- this one starts at the parameter value
    public Counter(int init){
         myValue = init;
    }

    // accessor -- used to fetch the counter's value
    public int getValue(){
         return myValue;
    }

    // used to print the counter's value
    public void tellValue(){
         System.out.println("  From tellValue: I have value " + myValue);
    }

    // used to automatically print the counter's value   
    public String toString(){
         return "  From toString: I have value " + myValue;
    }

    // modifier -- used to increment the counter by 1
    public void incrementCounter(){
         myValue++;
    }

    // modifier -- used to increment the counter by parameter value
    public void incrementCounter(int incr){
         myValue += incr;
    }

    // modifier -- used to decrement the counter by 1
    public void decrementCounter(){
         myValue--;
    }

    // modifier -- used to decrement the counter by parameter value
    public void decrementCounter(int incr){
         myValue -= incr;
    }
}      



// CounterDemo.java: Test and demonstrate counter objects
 public class CounterDemo {

    public static void main(String args[]) {
        // create a counter, using the Counter() constructor
        int thisCounterValue;
        Counter thisCounter = new Counter();

        // first work with thisCounter
        System.out.println("After Constructing thisCounter");
        thisCounter.tellValue();

        System.out.println("Increment thisCounter");
        thisCounter.incrementCounter();
        thisCounter.tellValue();

        System.out.println("Increment thisCounter by 4");
        thisCounter.incrementCounter(4);
        thisCounter.tellValue();

        System.out.println("Decrement thisCounter");
        thisCounter.decrementCounter();
        thisCounter.tellValue();

        System.out.println("Decrement thisCounter by 8");
        thisCounter.decrementCounter(8);
        thisCounter.tellValue();

        System.out.println("Call to GetValue for thisCounter");
        thisCounterValue = thisCounter.getValue();    
        System.out.println("Current Value is: " + thisCounterValue);

        thisCounter.incrementCounter();
        System.out.println("Call to toString, after incrementing ");
        System.out.println( thisCounter );

        // we can create any number of separate counters
        // so try out another counter: anotherCounter, this one
        // uses the constructor Counter(int)
        Counter anotherCounter = new Counter(100);
        System.out.println("After constructing anotherCounter");
        anotherCounter.tellValue();
        // continue as before
    }
}

 
After Constructing thisCounter
  From tellValue: I have value 0
Increment thisCounter
  From tellValue: I have value 1
Increment thisCounter by 4
  From tellValue: I have value 5
Decrement thisCounter
  From tellValue: I have value 4
Decrement thisCounter by 8
  From tellValue: I have value -4
Call to GetValue for thisCounter
Current Value is: -4
Call to toString, after incrementing 
  From toString: I have value -3
After constructing anotherCounter
  From tellValue: I have value 100