contrib/jwrapper: intro a practical example use of jwrapper

[nit.git] / contrib / jwrapper / examples / queue / Queue.java

diff --git a/contrib/jwrapper/examples/queue/Queue.java b/contrib/jwrapper/examples/queue/Queue.java
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+/*
+* This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+*/
+
+import java.util.*;
+
+public class Queue
+{
+    // function pointer
+    public native void printError( String errorMsg );
+
+    // internal list
+    private LinkedList<String> list;
+
+    public Queue()
+    {
+        list = new LinkedList<String>();
+    }
+
+    public void push( String element )
+    {
+        System.out.print( "From java, pushing " );
+        System.out.print( element );
+        System.out.print( "\n" );
+        list.addLast( element );
+    }
+
+    public String pop() // knows where is native printError
+    {
+        String element;
+
+        try
+        {
+            element = list.removeFirst();
+        }
+        catch ( NoSuchElementException e )
+        {
+            printError( "From java, empty queue." );
+            element = null;
+            throw e;
+        }
+
+        System.out.print( "From java, popping " );
+        System.out.print( element );
+        System.out.print( "\n" );
+
+        return element;
+    }
+}