Add State

src/decorator/ComplexTaxTest.java → src/decorator/ComplexTaxMain.java

@@ -1,6 +1,6 @@
 package decorator;
 
-public class ComplexTaxTest {
+public class ComplexTaxMain {
 
 	public static void main(String[] args) {
 		System.out.println("--------------------------------------------- Begin Test for Complex Tax");

src/state/Annotation.txt

@@ -0,0 +1,25 @@
+##############################
+#           State            #
+##############################
+
+
+
+
+
+##### Language - EN
+
+- When we have states and we want to change some implementation according to the state, or even block the state by going to a state that it shouldn't.
+
+- The main situation that gives rise to the Design Pattern State is the need to implement a state machine. Usually,
+the control of possible transitions are several and complex, making the implementation not simple.
+The State helps to keep track of the states simple and organized by creating classes that represent each state and know how to control the transitions.
+
+
+
+##### Language - PT-BR
+
+- Quando temos estados e queremos alterar alguma implementação de acordo com o estado, ou até mesmo bloquear o estado indo para um estado que não deve.
+
+- A principal situação que faz emergir o Design Pattern State é a necessidade de implementação de uma máquina de estados. Geralmente, 
+o controle das possíveis transições são vários e complexos, fazendo com que a implementação não seja simples. 
+O State auxilia a manter o controle dos estados simples e organizados através da criação de classes que representem cada estado e saiba controlar as transições.

src/state/Approved.java

@@ -0,0 +1,25 @@
+package state;
+
+public class Approved implements StateOfBudget {
+
+	@Override
+	public void applyExtraDiscount(Budget budget) {
+		budget.value -= budget.value * 0.02;
+	}
+
+	@Override
+	public void toApprove(Budget budget) {
+		throw new RuntimeException("Budget is already approved.");
+	}
+
+	@Override
+	public void toDisapprove(Budget budget) {
+		throw new RuntimeException("Budget is already disapprove.");
+	}
+
+	@Override
+	public void toFinish(Budget budget) {
+		budget.currentState = new Finished();
+	}
+
+}

src/state/Budget.java

@@ -0,0 +1,51 @@
+package state;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import templateMethod.Item;
+
+public class Budget {
+
+	protected double value;
+	private final List<Item> items;
+
+	protected StateOfBudget currentState;
+
+	public Budget(double value) {
+		super();
+		this.value = value;
+		items = new ArrayList<Item>();
+		currentState = new OnApproval(); //State Initial
+	}
+
+	public double getValue() {
+		return value;
+	}
+
+	public void addItem(Item item) {
+		items.add(item);
+	}
+
+	public List<Item> getItems() {
+		return Collections.unmodifiableList(items);// unmodifiableList -> Return a List immutable.
+	}
+
+	public void applyExtraDiscount() {
+		currentState.applyExtraDiscount(this); // this -> we pass the object itself, because this is where we want to make the changes
+	}
+
+	public void toApprove() {
+		currentState.toApprove(this);
+	}
+
+	public void toDisapprove() {
+		currentState.toDisapprove(this);
+	}
+
+	public void toFinish() {
+		currentState.toFinish(this);
+	}
+
+}

src/state/Disapproved.java

@@ -0,0 +1,25 @@
+package state;
+
+public class Disapproved implements StateOfBudget {
+
+	@Override			
+	public void applyExtraDiscount(Budget budget) {
+		throw new RuntimeException("Disapproved budget does not receive extra discounts."); 
+	}
+
+	@Override
+	public void toApprove(Budget budget) {
+		throw new RuntimeException("Disapproved budgets cannot be approved.");
+	}
+
+	@Override
+	public void toDisapprove(Budget budget) {
+		throw new RuntimeException("Budget is already disapprove.");
+	}
+
+	@Override
+	public void toFinish(Budget budget) {
+		budget.currentState = new Finished();
+	}
+
+}

src/state/Finished.java

@@ -0,0 +1,25 @@
+package state;
+
+public class Finished implements StateOfBudget {
+
+	@Override
+	public void applyExtraDiscount(Budget budget) {
+		throw new RuntimeException("Finalized budget do not receive extra discounts.");
+	}
+
+	@Override
+	public void toApprove(Budget budget) {
+		throw new RuntimeException("Budgets already finalized.");
+	}
+
+	@Override
+	public void toDisapprove(Budget budget) {
+		throw new RuntimeException("Budgets already finalized.");
+	}
+
+	@Override
+	public void toFinish(Budget budget) {
+		throw new RuntimeException("Budgets already finalized.");
+	}
+
+}

src/state/OnApproval.java

@@ -0,0 +1,25 @@
+package state;
+
+public class OnApproval implements StateOfBudget {
+
+	@Override
+	public void applyExtraDiscount(Budget budget) {
+		budget.value -= budget.value * 0.05;
+	}
+
+	@Override
+	public void toApprove(Budget budget) {
+		budget.currentState = new Approved();
+	}
+
+	@Override
+	public void toDisapprove(Budget budget) {
+		budget.currentState = new Disapproved();
+	}
+
+	@Override
+	public void toFinish(Budget budget) {
+		throw new RuntimeException("Approving budgets, so they can't go straight to finalized.");
+	}
+
+}

src/state/StateMain.java

@@ -0,0 +1,30 @@
+package state;
+
+public class StateMain {
+
+	public static void main(String[] args) {
+		System.out.println("--------------------------------------------- Begin Test State");
+
+
+		Budget budgetExtra = new Budget(500);
+
+		// Current State = OnApproval = 0.05
+		budgetExtra.applyExtraDiscount();
+		System.out.println("Aplly Extra Discount: " + budgetExtra.getValue()); // 500 -= 500 * 0.05 ->>> 475.0
+
+
+		// Current State HERE = Approve = 0.02
+		budgetExtra.toApprove();
+		budgetExtra.applyExtraDiscount();
+		System.out.println("Aplly Extra Discount with 'approve': " + budgetExtra.getValue()); // 475.0 -= 475.0 * 0.02 ->>> 465.0
+
+
+		// the code below will generate an error, as we cannot apply a discount for this state ''
+		budgetExtra.toFinish(); //OK - PROCESS FINISH
+		//budgetExtra.applyExtraDiscount(); //Error
+
+
+		System.out.println("--------------------------------------------- End Test State");
+	}
+
+}

src/state/StateOfBudget.java

@@ -0,0 +1,12 @@
+package state;
+
+public interface StateOfBudget {
+
+	void applyExtraDiscount(Budget budget);
+
+	// Apply State
+	void toApprove(Budget budget);
+	void toDisapprove(Budget budget);
+	void toFinish(Budget budget);
+
+}