finished uebung09

src/uebung09/chess/Board.java

@@ -3,6 +3,7 @@ package uebung09.chess;
 import java.util.Iterator;
 
 import uebung09.iterator.Array2dIterator;
+import uebung09.iterator.SkipNullIterator;
 
 
 public class Board implements Iterable<Piece>{
@@ -50,22 +51,21 @@ public class Board implements Iterable<Piece>{
     }
 
     public String toString() {
-        // StringBuilder s = new StringBuilder("[");
+        StringBuilder s = new StringBuilder("[");
 
-        // for(Piece p : this) {
+        for(Piece p : this) {
-        //     s.append(p.toString());
+            s.append(p.toString());
-        // }
+        }
 
-        // s.append("]");
+        s.append("]");
 
-        // return s.toString();
+        return s.toString();
-        return "";
     }
 
     @Override
     public Iterator<Piece> iterator() {
         // TODO Auto-generated method stub
-        return new Array2dIterator<>(field);
+        return new SkipNullIterator<>(new Array2dIterator<>(field));
         // throw new UnsupportedOperationException("Unimplemented method 'iterator'");
     }
 }

src/uebung09/iterator/SkipNullIterator.java

@@ -1,26 +1,42 @@
 package uebung09.iterator;
 
 import java.util.Iterator;
-import java.util.List;
+import java.util.NoSuchElementException;
 
 public class SkipNullIterator<T> implements Iterator<T>{
+    private final Iterator<T> iterator;
+    private T nextItem;
+    private boolean hasNext;
 
-    public SkipNullIterator(Iterator i){
+    public SkipNullIterator(Iterator<T> iterator) {
+        this.iterator = iterator;
+        advance();
+    }
 
+    private void advance() {
+        hasNext = false;
+        nextItem = null;
+        while (iterator.hasNext()) {
+            nextItem = iterator.next();
+            if (nextItem != null) {
+                hasNext = true;
+                break;
+            }
+        }
     }
 
     @Override
     public boolean hasNext() {
-        // TODO Auto-generated method stub
+        return hasNext;
-        throw new UnsupportedOperationException("Unimplemented method 'hasNext'");
     }
 
     @Override
     public T next() {
-        // TODO Auto-generated method stub
+        if (!hasNext) {
-        throw new UnsupportedOperationException("Unimplemented method 'next'");
+            throw new NoSuchElementException();
+        }
+        T currentItem = nextItem;
+        advance();
+        return currentItem;
     }
-
-    
-
 }