Can't use an inherited class

[Unca Paddy]

Background: I am using Bruce Eckel's eBook, "Thinking in Java", 3rd ed.
Problem: I try to use inheritance to extend a class, but a method that *should* be available seems not to be:

class Cleanser {
private String s = new String("Cleanser");
public void append(String a) { s += a; }
public void dilute() { append(" dilute()"); }
public void apply() { append("apply()"); }
public void scrub() { append("scrub()"); }
public String toString() { return s; }
public static void main (String[] args) {
Cleanser x = new Cleanser();
x.dilute(); x.apply(); x.scrub();
System.out.println(x);
}
}

class Detergent extends Cleanser {
// change a method:
public void scrub() {
append ("Detergent.scrub()");
super.scrub();
}
// add methods to the interface:
public void foam() { append(" foam()"); }
// test the new class:
public static void main (String[] args) {
Detergent x = new Detergent();
x.dilute(); x.apply(); x.scrub(); x.foam();
System.out.println (x);
System.out.println ("Testing the base class" );
Cleanser.main(args);
}
}

//++++++++++
//
// my extension:
//
+++++++++++

public class Autoclave extends Detergent {
public void scrub() {
System.out.println("Autoclave Scrub");
}

public void sterilize() {
System.out.println ("Sterilizing");
}

public static void main (String[] args) {
Autoclave a = new Autoclave();
Cleanser.dilute();
a.apply(); a.scrub(); a.foam(); a.sterilize();
//System.out.println ("Calling Cleanser scrub()");
}
}

//++++++++++++++++++++++++

When I compile Autoclave.java , javac complains that it cannot find the symbol foam()

What am I doing wrong?

[prometheuzz]

public class Autoclave extends Detergent {

    public void scrub() {
        System.out.println("Autoclave Scrub");
    }
    
    public void sterilize() {
        System.out.println ("Sterilizing");
    }
    
    public static void main (String[] args) {
        Autoclave a = new Autoclave();
        a.dilute();   // it was: Cleanser.dilute(); 
        a.apply(); a.scrub(); a.foam(); a.sterilize();
    }
}

You were trying call Cleanser.dilute(), which is a non-static method, from a static context. Read http://mindprod.com/jgloss/static.html if you find this static-thing confusing.

Good luck.

[Norm]

Don't understand your reference to foam(). Was that just a test?

Autoclave.java(50,10) : error J0242: Cannot make static call to non-static method 'void dilute()'