// Purpose. Template Method design pattern

// 1. Standardize the skeleton of an algorithm in a base class "template" method
// 2. Common implementations of individual steps are defined in the base class
// 3. Steps requiring peculiar implementations are "placeholders" in base class
// 4. Derived classes can override placeholder methods
// 5. Derived classes can override implemented methods
// 6. Derived classes can override and "call back to" base class methods

abstract class Generalization {
// 1. Standardize the skeleton of an algorithm in a "template" method
public void findSolution() {
stepOne();
stepTwo();
stepThr();
stepFor();
}
// 2. Common implementations of individual steps are defined in base class
protected void stepOne() { System.out.println( "Generalization.stepOne" ); }
// 3. Steps requiring peculiar impls are "placeholders" in the base class
abstract protected void stepTwo();
abstract protected void stepThr();
protected void stepFor() { System.out.println( "Generalization.stepFor" ); }
}

abstract class Specialization extends Generalization {
// 4. Derived classes can override placeholder methods
// 1. Standardize the skeleton of an algorithm in a "template" method
protected void stepThr() {
step3_1();
step3_2();
step3_3();
}
// 2. Common implementations of individual steps are defined in base class
protected void step3_1() { System.out.println( "Specialization.step3_1" ); }
// 3. Steps requiring peculiar impls are "placeholders" in the base class
abstract protected void step3_2();
protected void step3_3() { System.out.println( "Specialization.step3_3" ); }
}

class Realization extends Specialization {
// 4. Derived classes can override placeholder methods
protected void stepTwo() { System.out.println( "Realization .stepTwo" ); }
protected void step3_2() { System.out.println( "Realization .step3_2" ); }
// 5. Derived classes can override implemented methods
// 6. Derived classes can override and "call back to" base class methods
protected void stepFor() {
System.out.println( "Realization .stepFor" );
super.stepFor();
} }

class TemplateMethodDemo {
public static void main( String[] args ) {
Generalization algorithm = new Realization();
algorithm.findSolution();
} }

// Generalization.stepOne
// Realization .stepTwo
// Specialization.step3_1
// Realization .step3_2
// Specialization.step3_3
// Realization .stepFor
// Generalization.stepFor