Create coding10.java

coding10.java

@@ -0,0 +1,32 @@
+// Java Iterator interface reference:
+// https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
+
+class PeekingIterator implements Iterator<Integer> {
+    private Iterator<Integer> iterator;
+    private Integer elem;
+	public PeekingIterator(Iterator<Integer> iterator) {
+	    // initialize any member here.
+        this.iterator=iterator;
+        if(iterator.hasNext())
+            elem=iterator.next();
+	}
+
+    // Returns the next element in the iteration without advancing the iterator.
+	public Integer peek() {
+        return elem;
+	}
+
+	// hasNext() and next() should behave the same as in the Iterator interface.
+	// Override them if needed.
+	@Override
+	public Integer next() {
+	    Integer ans=elem;
+        elem=iterator.hasNext()?iterator.next():null;
+        return ans;
+	}
+
+	@Override
+	public boolean hasNext() {
+	    return elem!=null;
+	}
+}