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--- java:inner_classes [2020/03/23 08:40] – gthanos
+++ java:inner_classes [Unknown date] (current) – external edit (Unknown date) 127.0.0.1
@@ Line 10: / Line 10: @@
 <code java LinkedList.java>
 /* A linked list with sentinels at head and tail.
  */
 public class LinkedList<E> {
   private Node<E> head, tail;
+  int size;
   public LinkedList() {
@@ Line 20: / Line 20: @@
     tail = new Node<>(null, head, null);
     head.setNext(tail);
+    size = 0;
   }
@@ Line 67: / Line 68: @@
   // append in the end
-  public void add(E elem) {
+  public boolean add(E elem) {
     Node<E> plus = new Node<E>(tail, tail.getPrev(), elem);
     tail.getPrev().setNext(plus);
     tail.setPrev(plus);
+    size++;
+    return true;
+  }
+  public boolean add(int index, E elem) {
+    if(index>size)
+      return false;
+    Node<E> curr = head.next;
+    for(int i=0; curr != tail && i<index; i++) {
+      curr = curr.next;
+    }
+    Node<E> plus = new Node<E>(curr, curr.prev, elem);
+    curr.prev.next = plus;
+    curr.prev = plus;
+    size++;
+    return true;
   }
@@ Line 93: / Line 110: @@
     }
     return -1;
+  }
+  int size() {
+    return size;
   }
 }
@@ Line 106: / Line 127: @@
   public static final int RANGE = 8 * SIZE;
-  public static void main(String[] args) {
+  static void print(LinkedList<Integer> list){
-    Random rand = new Random( new Date().getTime());
-    LinkedList<Integer> list = new LinkedList<>();
-    for(int i=0; i<SIZE; i++) {
-      list.add(rand.nextInt(RANGE));
-    }
     Iterator<Integer> it = list.iterator();
@@ Line 119: / Line 135: @@
     }
     System.out.println();
+  }
+  public static void main(String[] args) {
+    Random rand = new Random( new Date().getTime());
+    LinkedList<Integer> list = new LinkedList<>();
+    for(int i=0; i<SIZE; i++) {
+      int value = rand.nextInt(RANGE);
+      int pos = rand.nextInt(list.size()+1);
+      System.out.format("Adding %d at %d\n", value, pos);
+      list.add(pos,value);
+      print(list);
+    }
+    print(list);
     // Remove all elements less than RANGE/2
     System.out.println("Remove values < "+RANGE/2);
-    it = list.iterator();
+    Iterator<Integer> it = list.iterator();
     while(it.hasNext()) {
       int value = it.next();
@@ Line 131: / Line 160: @@
       }
     }
+    print(list);
-    // Print list
-    it = list.iterator();
-    while(it.hasNext()) {
-      System.out.print(it.next()+"  ");
-    }
-    System.out.println();
   }
 }