Update java samples

ortools/linear_solver/samples/BasicExample.java

@@ -22,9 +22,9 @@ import com.google.ortools.linearsolver.MPSolver;
 import com.google.ortools.linearsolver.MPVariable;
 // [END import]
 
-/** Minimal Linear Programming example to showcase calling the solver.*/
-public class BasicExample {
-  public static void main(String[] args) throws Exception {
+/** Minimal Linear Programming example to showcase calling the solver. */
+public final class BasicExample {
+  public static void main(String[] args) {
     Loader.loadNativeLibraries();
     // [START solver]
     // Create the linear solver with the GLOP backend.
@@ -67,5 +67,7 @@ public class BasicExample {
     System.out.println("y = " + y.solutionValue());
     // [END print_solution]
   }
+
+  private BasicExample() {}
 }
 // [END program]

ortools/linear_solver/samples/LinearProgrammingExample.java

@@ -21,9 +21,9 @@ import com.google.ortools.linearsolver.MPSolver;
 import com.google.ortools.linearsolver.MPVariable;
 // [END import]
 
-/** Simple linear programming example.*/
-public class LinearProgrammingExample {
-  public static void main(String[] args) throws Exception {
+/** Simple linear programming example. */
+public final class LinearProgrammingExample {
+  public static void main(String[] args) {
     Loader.loadNativeLibraries();
     // [START solver]
     MPSolver solver = MPSolver.createSolver("GLOP");
@@ -84,5 +84,7 @@ public class LinearProgrammingExample {
     System.out.println("Problem solved in " + solver.iterations() + " iterations");
     // [END advanced]
   }
+
+  private LinearProgrammingExample() {}
 }
 // [END program]

ortools/linear_solver/samples/SimpleLpProgram.java

@@ -22,9 +22,9 @@ import com.google.ortools.linearsolver.MPSolver;
 import com.google.ortools.linearsolver.MPVariable;
 // [END import]
 
-/** Minimal Linear Programming example to showcase calling the solver.*/
-public class SimpleLpProgram {
-  public static void main(String[] args) throws Exception {
+/** Minimal Linear Programming example to showcase calling the solver. */
+public final class SimpleLpProgram {
+  public static void main(String[] args) {
     Loader.loadNativeLibraries();
     // [START solver]
     // Create the linear solver with the GLOP backend.
@@ -87,5 +87,7 @@ public class SimpleLpProgram {
     System.out.println("Problem solved in " + solver.iterations() + " iterations");
     // [END advanced]
   }
+
+  private SimpleLpProgram() {}
 }
 // [END program]

ortools/linear_solver/samples/SimpleMipProgram.java

@@ -23,8 +23,8 @@ import com.google.ortools.linearsolver.MPVariable;
 // [END import]
 
 /** Minimal Mixed Integer Programming example to showcase calling the solver. */
-public class SimpleMipProgram {
-  public static void main(String[] args) throws Exception {
+public final class SimpleMipProgram {
+  public static void main(String[] args) {
     Loader.loadNativeLibraries();
     // [START solver]
     // Create the linear solver with the SCIP backend.
@@ -88,5 +88,7 @@ public class SimpleMipProgram {
     System.out.println("Problem solved in " + solver.nodes() + " branch-and-bound nodes");
     // [END advanced]
   }
+
+  private SimpleMipProgram() {}
 }
 // [END program]