refactor: Made Task::id nullable/Optional for semantic reasons

better use of builder semantics in task and crop creation

src/main/java/ch/zhaw/gartenverwaltung/io/JsonTaskList.java

@@ -103,10 +103,9 @@ public class JsonTaskList implements TaskList {
         if(taskMap.isEmpty()) {
             loadTaskListFromFile();
         }
-        if(task.getId() == 0) {
-            task.withId(idProvider.incrementAndGet());
-        }
-        taskMap.put(task.getId(), task);
+        long id = task.getId().orElse(idProvider.incrementAndGet());
+
+        taskMap.put(id, task.withId(id));
         writeTaskListToFile();
     }
 
@@ -122,8 +121,9 @@ public class JsonTaskList implements TaskList {
         if(taskMap.isEmpty()) {
             loadTaskListFromFile();
         }
-        if(taskMap.containsKey(task.getId())){
-            taskMap.remove(task.getId());
+        Long taskId = task.getId().orElseThrow(IOException::new);
+        if(taskMap.containsKey(taskId)){
+            taskMap.remove(taskId);
             writeTaskListToFile();
         }
     }
@@ -163,7 +163,7 @@ public class JsonTaskList implements TaskList {
 
             taskMap = result.stream()
                     .collect(HashMap::new,
-                        (res, task) -> res.put(task.getId(), task),
+                        (res, task) -> res.put(task.getId().orElse(0L), task),
                         (existing, replacement) -> {});
         }
 

src/main/java/ch/zhaw/gartenverwaltung/types/Task.java

@@ -9,7 +9,7 @@ import java.util.Optional;
  * May be created using the builder pattern.
  */
 public class Task {
-    private long id;
+    private Long id;
     private final String name;
     private final String description;
     private final LocalDate startDate;
@@ -62,7 +62,7 @@ public class Task {
     }
 
     // Getters
-    public long getId() { return id; }
+    public Optional<Long> getId() { return Optional.ofNullable(id); }
     public String getName() { return name; }
     public String getDescription() { return description; }
     public LocalDate getStartDate() { return startDate; }

src/main/java/ch/zhaw/gartenverwaltung/types/TaskTemplate.java

@@ -34,6 +34,7 @@ public class TaskTemplate {
     public void setRelativeEndDate(Integer relativeEndDate) {
         this.relativeEndDate = relativeEndDate;
     }
+
     public void setInterval(Integer interval) {
         this.interval = interval;
     }
@@ -45,13 +46,10 @@ public class TaskTemplate {
     }
 
     public Task generateTask(LocalDate realStartDate, long cropId) {
-        Task task = new Task(name, description, realStartDate.plusDays(relativeStartDate), cropId);
-        if (relativeEndDate != null) {
-            task.withEndDate(realStartDate.plusDays(relativeEndDate));
-        }
-        if (interval != null) {
-            task.withInterval(interval);
-        }
-        return task;
+        LocalDate endDate = relativeEndDate != null ? realStartDate.plusDays(relativeEndDate) : null;
+
+        return new Task(name, description, realStartDate.plusDays(relativeStartDate), cropId)
+                .withInterval(interval)
+                .withEndDate(endDate);
     }
 }