math_opt: add java wrapper

* add ortools/java/com/google/ortools/mathopt/
* add ortools/java/com/google/ortools/mathopt/testing

Author: Mizux

cmake/java.cmake

@@ -108,12 +108,19 @@ file(GLOB_RECURSE proto_java_files RELATIVE ${PROJECT_SOURCE_DIR}
   "ortools/sat/sat_parameters.proto"
   "ortools/util/*.proto"
   )
-if(USE_PDLP)
+list(REMOVE_ITEM proto_java_files "ortools/constraint_solver/assignment.proto")
+list(REMOVE_ITEM proto_java_files "ortools/util/testdata/wrappers_test_message.proto")
+if(BUILD_MATH_OPT)
+  file(GLOB_RECURSE mathopt_proto_java_files RELATIVE ${PROJECT_SOURCE_DIR}
+    "ortools/math_opt/*.proto"
+    "ortools/math_opt/solvers/*.proto"
+  )
+  list(APPEND proto_java_files ${mathopt_proto_java_files})
+endif()
+if(USE_PDLP OR BUILD_MATH_OPT)
   file(GLOB_RECURSE pdlp_proto_java_files RELATIVE ${PROJECT_SOURCE_DIR} "ortools/pdlp/*.proto")
   list(APPEND proto_java_files ${pdlp_proto_java_files})
 endif()
-list(REMOVE_ITEM proto_java_files "ortools/constraint_solver/assignment.proto")
-list(REMOVE_ITEM proto_java_files "ortools/util/testdata/wrappers_test_message.proto")
 foreach(PROTO_FILE IN LISTS proto_java_files)
   #message(STATUS "protoc proto(java): ${PROTO_FILE}")
   get_filename_component(PROTO_DIR ${PROTO_FILE} DIRECTORY)
@@ -273,6 +280,9 @@ foreach(SUBPROJECT IN ITEMS
 endforeach()
 # from ortools/linear_solver/java
 target_link_libraries(jni${JAVA_ARTIFACT} PRIVATE jnimodelbuilder)
+add_subdirectory(ortools/math_opt/core/java)
+target_link_libraries(jni${JAVA_ARTIFACT} PRIVATE mathopt_java_jni_helper)
+target_link_libraries(jni${JAVA_ARTIFACT} PRIVATE jnimathopt)
 add_subdirectory(ortools/sat/java)
 target_link_libraries(jni${JAVA_ARTIFACT} PRIVATE jnisat)
 target_link_libraries(jni${JAVA_ARTIFACT} PRIVATE jni_cp_model_proto)

ortools/java/com/google/ortools/BUILD.bazel

@@ -28,6 +28,7 @@ cc_binary(
         "//ortools/graph/java:graph_cc",
         "//ortools/init/java:init_cc",
         "//ortools/linear_solver/java:modelbuilder_cc",
+        "//ortools/math_opt/core/java:solver_swig_cc",
         "//ortools/sat/java:cp_model_proto_cc",
         "//ortools/sat/java:sat_cc",
         "//ortools/util/java:java_swig_solve_interrupter_swig_cc",
@@ -49,6 +50,7 @@ cc_binary(
         "//ortools/graph/java:graph_cc",
         "//ortools/init/java:init_cc",
         "//ortools/linear_solver/java:modelbuilder_cc",
+        "//ortools/math_opt/core/java:solver_swig_cc",
         "//ortools/sat/java:cp_model_proto_cc",
         "//ortools/sat/java:sat_cc",
         "//ortools/util/java:java_swig_solve_interrupter_swig_cc",
@@ -71,6 +73,7 @@ cc_binary(
         "//ortools/graph/java:graph_cc",
         "//ortools/init/java:init_cc",
         "//ortools/linear_solver/java:modelbuilder_cc",
+        "//ortools/math_opt/core/java:solver_swig_cc",
         "//ortools/sat/java:cp_model_proto_cc",
         "//ortools/sat/java:sat_cc",
         "//ortools/util/java:java_swig_solve_interrupter_swig_cc",

ortools/java/com/google/ortools/mathopt/AuxiliaryObjective.java

@@ -0,0 +1,63 @@
+// Copyright 2010-2025 Google LLC
+// 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.mathopt;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * Additional objectives for optimization models with multiple hierarchical objectives.
+ *
+ * <p>Unlike the primary objective, auxiliary objectives have an id and can be deleted. Users who do
+ * not need these features (most users) can program against the parent class {@link Objective}
+ * instead, allowing more uniform treatment of the primary and auxiliary objectives.
+ */
+public final class AuxiliaryObjective extends Objective implements ModelElement {
+  private final long id;
+  private boolean deleted = false;
+
+  AuxiliaryObjective(
+      long priority, String name, long id, OnChangeListener listener, ModelId modelId) {
+    super(priority, name, listener, modelId);
+    Preconditions.checkArgument(id >= 0, "id should be nonnegative, was %s", id);
+    this.id = id;
+  }
+
+  @Override
+  public long getId() {
+    return id;
+  }
+
+  @Override
+  public boolean isDeleted() {
+    return deleted;
+  }
+
+  @Override
+  public String toString() {
+    String label = "Objective " + id;
+    if (getName().isEmpty()) {
+      return label;
+    } else {
+      return getName() + " (" + label + ")";
+    }
+  }
+
+  /**
+   * To be called when this objective is deleted from the model, ensures future modifications result
+   * in an error. It is an error to call this on the primary objective.
+   */
+  void markDeleted() {
+    deleted = true;
+  }
+}