java - Accessing parent class instance variables from child class instances -

so right now, have preprocessor class generates bunch of instance variable maps, , service class has setpreprocessor(preprocessor x) method, instance of service class able access maps preprocessor generated.

at moment, service class needs call 3 methods in succession; sake of simplicity, let's call them executephaseone, executephasetwo, , executephasethree. each of these 3 methods instantiate/modify service instance variables, of pointers service instance's preprocessor object.

my code has structure right now:

preprocessor preprocessor = new preprocessor(); preprocessor.preprocess(); service service = new service(); service.setpreprocessor(preprocessor); service.executephaseone(); service.executephasetwo(); service.executephasethree(); 

to better organize code, want put each executephasexxx() call in own separate subclass of service, , leave common data structures phases in parent class service. then, want have execute() method in service parent class executes 3 phases in succession:

class servicechildone extends service {     public void executephaseone() {         // stuff     } }  class servicechildtwo extends service {     public void executephasetwo() {         // stuff     } }  class servicechildthree extends service {     public void executephasethree() {         // stuff     } } 

edit:

the problem is, how write execute() method in service parent class? have:

public void execute() {     servicechildone childone = new servicechildone();     servicechildtwo childtwo = new servicechildtwo();     servicechildthree childthree = new servicechildthree();     system.out.println(childone.preprocessor); // prints null     childone.executephaseone();     childone.executephasetwo();     childone.executephasethree(); } 

however, childone, childtwo, , childthree objects aren't able access preprocessor instance variable lives in parent class service... how past problem?

use protected modifier preprocessor instance variable of service, so:

public class service {     protected preprocessor preprocessor; } 

then each subclass of service has this.preprocessor.