First java example

com/google/ortools/constraintsolver/JavaDecisionBuilder.java

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+// Copyright 2010 Google
+// 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.
+
+package com.google.ortools.constraintsolver;
+
+/**
+ * This class acts as a intermediate step between a c++ decision builder
+ * and a java one. Its main purpose is to catch the java exception launched
+ * when a failure occurs during the Next() call, and to return silently
+ * a FailDecision that will propagate the failure back to the C++ code.
+ *
+ */
+public class JavaDecisionBuilder extends DecisionBuilder {
+  /**
+   * This methods wraps the calls to next() and catches fail exceptions.
+   */
+  public final Decision nextWrap(Solver solver) {
+    try {
+      return next(solver);
+    } catch (FailException e) {
+      return solver.makeFailDecision();
+    }
+  }
+  /**
+   * This is the new method to subclass when defining a java decision builder.
+   */
+  public Decision next(Solver solver) throws FailException {
+    return null;
+  }
+}