update java example

tutorials/java/src/History.java

@@ -0,0 +1,47 @@
+
+import java.util.ArrayList;
+
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+/**
+ * Implement a simple history list for command input
+ * @author krakjoe
+ */
+public class History extends ArrayList<String> {
+    private Integer position = new Integer(0);
+    
+    public History() {
+        super();
+    }
+    
+    @Override public boolean add(String text) {
+        String last = last();
+        if (text != null) {
+           if (last == null || !last.equals(text)) {
+               if (super.add(text)) {
+                   position = size();
+                   return true;
+               }
+           }
+        }
+        return false;
+    }
+    
+    public String last() {
+        if (position >= 1) {
+            position--;
+            return get(position);
+        } else return new String();
+    }
+    
+    public String next() {
+        if (position+1 < size()) {
+            position++;
+            return get(position);
+        } else return new String();
+    }
+}