From 4c9ea991cc5edacd714fc566ce572a417181ce0c Mon Sep 17 00:00:00 2001
From: PRIFTI <dionis.prifti.sp@lhind.dlh.de>
Date: Tue, 15 Jan 2019 21:38:40 +0100
Subject: [PATCH] BAEL-2441: Providing example for Implementing simple State
 Machine with Java Enums.

---
 .../enumstatemachine/LeaveRequestState.java   | 46 +++++++++++++++++++
 .../LeaveRequestStateTest.java                | 41 +++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestState.java
 create mode 100644 algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestStateTest.java

diff --git a/algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestState.java b/algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestState.java
new file mode 100644
index 0000000000..5153c2e18e
--- /dev/null
+++ b/algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestState.java
@@ -0,0 +1,46 @@
+package com.baeldung.algorithms.enumstatemachine;
+
+public enum LeaveRequestState {
+
+    Submitted {
+        @Override
+        public LeaveRequestState nextState() {
+            System.out.println("Starting the Leave Request and sending to Team Leader for approval.");
+            return Escalated;
+        }
+
+        @Override
+        public String responsiblePerson() {
+            return "Employee";
+        }
+    },
+    Escalated {
+        @Override
+        public LeaveRequestState nextState() {
+            System.out.println("Reviewing the Leave Request and escalating to Department Manager.");
+            return Approved;
+        }
+
+        @Override
+        public String responsiblePerson() {
+            return "Team Leader";
+        }
+    },
+    Approved {
+        @Override
+        public LeaveRequestState nextState() {
+            System.out.println("Approving the Leave Request.");
+            return this;
+        }
+
+        @Override
+        public String responsiblePerson() {
+            return "Department Manager";
+        }
+    };
+
+    public abstract String responsiblePerson();
+
+    public abstract LeaveRequestState nextState();
+
+}
diff --git a/algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestStateTest.java b/algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestStateTest.java
new file mode 100644
index 0000000000..b209dcb2fb
--- /dev/null
+++ b/algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/enumstatemachine/LeaveRequestStateTest.java
@@ -0,0 +1,41 @@
+package com.baeldung.algorithms.enumstatemachine;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class LeaveRequestStateTest {
+
+    @Test
+    public void givenLeaveRequest_whenStateEscalated_thenResponsibleIsTeamLeader() {
+        LeaveRequestState state = LeaveRequestState.Escalated;
+
+        String responsible = state.responsiblePerson();
+
+        assertEquals(responsible, "Team Leader");
+    }
+
+
+    @Test
+    public void givenLeaveRequest_whenStateApproved_thenResponsibleIsDepartmentManager() {
+        LeaveRequestState state = LeaveRequestState.Approved;
+
+        String responsible = state.responsiblePerson();
+
+        assertEquals(responsible, "Department Manager");
+    }
+
+    @Test
+    public void givenLeaveRequest_whenNextStateIsCalled_thenStateIsChanged() {
+        LeaveRequestState state = LeaveRequestState.Submitted;
+
+        state = state.nextState();
+        assertEquals(state, LeaveRequestState.Escalated);
+
+        state = state.nextState();
+        assertEquals(state, LeaveRequestState.Approved);
+
+        state = state.nextState();
+        assertEquals(state, LeaveRequestState.Approved);
+    }
+}