add bazel java POC; works with algorithms and graph

ortools/graph/samples/BUILD.bazel

@@ -11,7 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load(":code_samples.bzl", "code_sample_cc_py")
+load(":code_samples.bzl", "code_sample_cc_py", "code_sample_java")
 
 code_sample_cc_py(name = "assignment_linear_sum_assignment")
 
@@ -22,3 +22,13 @@ code_sample_cc_py(name = "balance_min_flow")
 code_sample_cc_py(name = "simple_max_flow_program")
 
 code_sample_cc_py(name = "simple_min_cost_flow_program")
+
+code_sample_java(name = "AssignmentLinearSumAssignment")
+
+code_sample_java(name = "AssignmentMinFlow")
+
+code_sample_java(name = "BalanceMinFlow")
+
+code_sample_java(name = "SimpleMaxFlowProgram")
+
+code_sample_java(name = "SimpleMinCostFlowProgram")

ortools/graph/samples/SimpleMaxFlowProgram.java

@@ -21,6 +21,7 @@ import com.google.ortools.graph.MaxFlow;
 /** Minimal MaxFlow program. */
 public final class SimpleMaxFlowProgram {
   public static void main(String[] args) throws Exception {
+    System.loadLibrary("jniortools");
     Loader.loadNativeLibraries();
     // [START solver]
     // Instantiate a SimpleMaxFlow solver.

ortools/graph/samples/code_samples.bzl

@@ -85,3 +85,19 @@ def code_sample_py(name):
 def code_sample_cc_py(name):
     code_sample_cc(name = name)
     code_sample_py(name = name)
+
+def code_sample_java(name):
+    native.java_binary(
+        name = name + "_java",
+        srcs = [name + ".java"],
+        main_class = "com.google.ortools.graph.samples." + name,
+        data = [
+            "//ortools/java/com/google/ortools:libjniortools.so",
+            "//ortools/java/com/google/ortools:libjniortools.dylib",
+            "//ortools/java/com/google/ortools:jniortools.dll",
+        ],
+        deps = [
+            "//ortools/graph/java:graph",
+            "//ortools/java/com/google/ortools:Loader"
+        ],
+    )