diff --git a/ortools/java/com/google/ortools/Loader.java b/ortools/java/com/google/ortools/Loader.java
index 0c2dbadd76..a1243d0839 100644
--- a/ortools/java/com/google/ortools/Loader.java
+++ b/ortools/java/com/google/ortools/Loader.java
@@ -26,14 +26,16 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.SimpleFileVisitor;
 import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.List;
 import java.util.Objects;
 
-/** Load native libraries needed for using ortools-java.*/
+/** Load native libraries needed for using ortools-java. */
 public class Loader {
   private static final String RESOURCE_PATH = "ortools-" + Platform.RESOURCE_PREFIX + "/";
 
-  /** Try to locate the native libraries directory.*/
+  /** Try to locate the native libraries directory. */
   private static URI getNativeResourceURI() throws IOException {
     ClassLoader loader = Loader.class.getClassLoader();
     URL resourceURL = loader.getResource(RESOURCE_PATH);
@@ -56,6 +58,7 @@ public class Loader {
 
   /**
    * Extract native resources in a temp directory.
+   *
    * @param resourceURI Native resource location.
    * @return The directory path containing all extracted libraries.
    */
@@ -98,34 +101,38 @@ public class Loader {
     return tempPath;
   }
 
-  /** Unpack and Load the native libraries needed for using ortools-java.*/
+  /** Unpack and Load the native libraries needed for using ortools-java. */
   private static boolean loaded = false;
 
   public static synchronized void loadNativeLibraries() {
-    if (!loaded) {
-      try {
-        // prints the name of the Operating System
-        // System.out.println("OS: " + System.getProperty("os.name"));
-        // System.out.println("Library: " + System.mapLibraryName("jniortools"));
-
-        System.loadLibrary("jniortools");
-        loaded = true;
-        return;
-      } catch (UnsatisfiedLinkError exception) {
-        // Do nothing.
-      }
-      try {
-        URI resourceURI = getNativeResourceURI();
-        Path tempPath = unpackNativeResources(resourceURI);
-        // Load the native library
-        System.load(tempPath.resolve(RESOURCE_PATH)
-                .resolve(System.mapLibraryName("jniortools"))
-                .toAbsolutePath()
-                .toString());
-        loaded = true;
-      } catch (IOException e) {
-        throw new RuntimeException(e);
-      }
+    // prints the name of the Operating System
+    // System.out.println("OS: " + System.getProperty("os.name"));
+    if (loaded) {
+      return;
+    }
+    try {
+      // System.out.println("System.loadLibrary(\"jniortools\")");
+      System.loadLibrary("jniortools");
+      loaded = true;
+      return;
+    } catch (UnsatisfiedLinkError e) {
+      // Do nothing.
+      // System.out.println("Can't System.loadLibrary(jniortools)");
+    }
+    try {
+      URI resourceURI = getNativeResourceURI();
+      Path tempPath = unpackNativeResources(resourceURI);
+      // Load the native library
+      // System.out.println("System.load(" + System.mapLibraryName("jniortools") + ")");
+      System.load(tempPath.resolve(RESOURCE_PATH)
+              .resolve(System.mapLibraryName("jniortools"))
+              .toAbsolutePath()
+              .toString());
+      loaded = true;
+      return;
+    } catch (IOException | UnsatisfiedLinkError e) {
+      // System.out.println("Can't System.load(jniortools)");
+      throw new RuntimeException(e);
     }
   }
 }
diff --git a/ortools/java/com/google/ortools/sat/CpModel.java b/ortools/java/com/google/ortools/sat/CpModel.java
index 72f86014e9..d740325277 100644
--- a/ortools/java/com/google/ortools/sat/CpModel.java
+++ b/ortools/java/com/google/ortools/sat/CpModel.java
@@ -943,6 +943,17 @@ public final class CpModel {
     modelBuilder.getSolutionHintBuilder().addValues(value);
   }
 
+  /** Adds hinting to a literal */
+  public void addHint(Literal lit, boolean value) {
+    if (isPositive(lit)) {
+      modelBuilder.getSolutionHintBuilder().addVars(lit.getIndex());
+      modelBuilder.getSolutionHintBuilder().addValues(value ? 1 : 0);
+    } else {
+      modelBuilder.getSolutionHintBuilder().addVars(negated(lit.getIndex()));
+      modelBuilder.getSolutionHintBuilder().addValues(value ? 0 : 1);
+    }
+  }
+
   /** Remove all solution hints */
   public void clearHints() {
     modelBuilder.clearSolutionHint();
@@ -1098,6 +1109,10 @@ public final class CpModel {
     return -index - 1;
   }
 
+  public boolean isPositive(Literal lit) {
+    return lit.getIndex() >= 0;
+  }
+
   /** Returns the model builder. */
   public CpModelProto.Builder getBuilder() {
     return modelBuilder;
diff --git a/ortools/java/com/google/ortools/sat/DoubleLinearExpr.java b/ortools/java/com/google/ortools/sat/DoubleLinearExpr.java
index 4850a25957..9da8333109 100644
--- a/ortools/java/com/google/ortools/sat/DoubleLinearExpr.java
+++ b/ortools/java/com/google/ortools/sat/DoubleLinearExpr.java
@@ -20,39 +20,39 @@ public class DoubleLinearExpr {
   private double offset;
 
   /** Creates a sum expression. */
-  static DoubleLinearExpr sum(IntVar[] variables) {
+  public static DoubleLinearExpr sum(IntVar[] variables) {
     return sumWithOffset(variables, 0.0);
   }
 
   /** Creates a sum expression. */
-  static DoubleLinearExpr sum(Literal[] literals) {
+  public static DoubleLinearExpr sum(Literal[] literals) {
     // We need the scalar product for the negative coefficient of negated Boolean variables.
     return sumWithOffset(literals, 0.0);
   }
 
   /** Creates a sum expression with a double offset. */
-  static DoubleLinearExpr sumWithOffset(IntVar[] variables, double offset) {
+  public static DoubleLinearExpr sumWithOffset(IntVar[] variables, double offset) {
     return new DoubleLinearExpr(variables, offset);
   }
 
   /** Creates a sum expression with a double offset. */
-  static DoubleLinearExpr sumWithOffset(Literal[] literals, double offset) {
+  public static DoubleLinearExpr sumWithOffset(Literal[] literals, double offset) {
     // We need the scalar product for the negative coefficient of negated Boolean variables.
     return new DoubleLinearExpr(literals, offset);
   }
 
   /** Creates a scalar product. */
-  static DoubleLinearExpr weightedSum(IntVar[] variables, double[] coefficients) {
+  public static DoubleLinearExpr weightedSum(IntVar[] variables, double[] coefficients) {
     return weightedSumWithOffset(variables, coefficients, 0.0);
   }
 
   /** Creates a scalar product. */
-  static DoubleLinearExpr weightedSum(Literal[] literals, double[] coefficients) {
+  public static DoubleLinearExpr weightedSum(Literal[] literals, double[] coefficients) {
     return weightedSumWithOffset(literals, coefficients, 0.0);
   }
 
   /** Creates a scalar product. */
-  static DoubleLinearExpr weightedSumWithOffset(
+  public static DoubleLinearExpr weightedSumWithOffset(
       IntVar[] variables, double[] coefficients, double offset) {
     if (variables.length != coefficients.length) {
       throw new CpModel.MismatchedArrayLengths(
@@ -62,7 +62,7 @@ public class DoubleLinearExpr {
   }
 
   /** Creates a scalar product with a double offset. */
-  static DoubleLinearExpr weightedSumWithOffset(
+  public static DoubleLinearExpr weightedSumWithOffset(
       Literal[] literals, double[] coefficients, double offset) {
     if (literals.length != coefficients.length) {
       throw new CpModel.MismatchedArrayLengths(
@@ -72,27 +72,27 @@ public class DoubleLinearExpr {
   }
 
   /** Creates a linear term (var * coefficient). */
-  static DoubleLinearExpr term(IntVar variable, double coefficient) {
+  public static DoubleLinearExpr term(IntVar variable, double coefficient) {
     return new DoubleLinearExpr(variable, coefficient, 0.0);
   }
 
   /** Creates a linear term (lit * coefficient). */
-  static DoubleLinearExpr term(Literal lit, double coefficient) {
+  public static DoubleLinearExpr term(Literal lit, double coefficient) {
     return new DoubleLinearExpr(lit, coefficient, 0.0);
   }
 
   /** Creates an affine expression (var * coefficient + offset). */
-  static DoubleLinearExpr affine(IntVar variable, double coefficient, double offset) {
+  public static DoubleLinearExpr affine(IntVar variable, double coefficient, double offset) {
     return new DoubleLinearExpr(variable, coefficient, offset);
   }
 
   /** Creates an affine expression (lit * coefficient + offset). */
-  static DoubleLinearExpr affine(Literal lit, double coefficient, double offset) {
+  public static DoubleLinearExpr affine(Literal lit, double coefficient, double offset) {
     return new DoubleLinearExpr(lit, coefficient, offset);
   }
 
-  /** Creates an constant expression. */
-  static DoubleLinearExpr constant(double value) {
+  /** Creates a constant expression. */
+  public static DoubleLinearExpr constant(double value) {
     return new DoubleLinearExpr(new IntVar[0], value);
   }