Solved Task 4

src/ch/zhaw/ads/ADS2_4_test.java

@@ -16,7 +16,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
  * @author
  * @version 1.00 2017/8/30
  */
-/**
+
 public class ADS2_4_test {
     MySortedList list;
 
@@ -79,4 +79,3 @@ public class ADS2_4_test {
         }
     }
 }
-*/

src/ch/zhaw/ads/MyList.java

@@ -133,7 +133,7 @@ public class MyList extends AbstractList {
         throw new UnsupportedOperationException("Method not implemented!");
     }
 
-    private class MyNode {
+    public class MyNode {
         private MyNode nextNode;
         private MyNode previousNode;
         private Object data;

src/ch/zhaw/ads/MySortedList.java

@@ -0,0 +1,42 @@
+package ch.zhaw.ads;
+
+public class MySortedList extends MyList {
+
+    @Override
+    public boolean add(Object o) {
+        if (!(o instanceof Comparable)) {
+            throw new IllegalArgumentException("Object is not comparable!");
+        }
+        if (head == null) {
+            head = new MyNode(null, null, o);
+            tail = head;
+        } else {
+            Comparable newData = (Comparable)o;
+            MyNode actual_Node = head;
+            while(newData.compareTo(actual_Node.getData()) > 0){
+                if(actual_Node.getNextNode() != null){
+                    actual_Node = actual_Node.getNextNode();
+                } else {
+                    //insert after actual
+                    MyNode newNode = new MyNode(null, actual_Node, o);
+                    actual_Node.setNextNode(newNode);
+                    tail = newNode;
+                    return true;
+                }
+            }
+            //insert before actual
+            MyNode newNode = new MyNode(actual_Node, actual_Node.getPreviousNode(), o);
+            if(actual_Node.getPreviousNode() != null) {
+                actual_Node.getPreviousNode().setNextNode(newNode);
+            }
+            actual_Node.setPreviousNode(newNode);
+            if(actual_Node == head)
+            {
+                head = newNode;
+            }
+        }
+        return true;
+    }
+
+
+}