Replace Random with ThreadLocalRandom

Author: tboychuk

account-data/src/main/java/com/bobocode/data/Accounts.java

@@ -5,12 +5,12 @@
 import io.codearte.jfairy.Fairy;
 import io.codearte.jfairy.producer.person.Person;
 
+import java.math.BigDecimal;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.util.List;
-import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 
-import static java.math.BigDecimal.valueOf;
 import static java.util.stream.Collectors.toList;
 import static java.util.stream.IntStream.range;
 
@@ -29,10 +29,10 @@ static List<Account> getAccountList(int size) {
     }
 
     static CreditAccount getCreditAccount() {
-        Random random = new Random();
         CreditAccount creditAccount = new CreditAccount();
         initializeFakeFields(creditAccount);
-        creditAccount.setCreditBalance(valueOf(random.nextInt(100_000)));
+        int intBalance = ThreadLocalRandom.current().nextInt(100_000);
+        creditAccount.setCreditBalance(BigDecimal.valueOf(intBalance));
 
         return creditAccount;
     }
@@ -47,7 +47,6 @@ static List<CreditAccount> getCreditAccountsList(int size) {
     private static void initializeFakeFields(Account account) {
         Fairy fairy = Fairy.create();
         Person person = fairy.person();
-        Random random = new Random();
 
         account.setFirstName(person.getFirstName());
         account.setLastName(person.getLastName());
@@ -56,7 +55,8 @@ private static void initializeFakeFields(Account account) {
                 person.getDateOfBirth().getYear(),
                 person.getDateOfBirth().getMonthOfYear(),
                 person.getDateOfBirth().getDayOfMonth()));
-        account.setBalance(valueOf(random.nextInt(200_000)));
+        int intBalance = ThreadLocalRandom.current().nextInt(200_000);
+        account.setBalance(BigDecimal.valueOf(intBalance));
         account.setCreationDate(LocalDateTime.now());
     }
 }

lambdas/src/main/java/com/bobocode/PredefinedInterfacePrimitives.java

@@ -1,6 +1,6 @@
 package com.bobocode;
 
-import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.function.DoubleSupplier;
 import java.util.function.IntToDoubleFunction;
 import java.util.function.LongBinaryOperator;
@@ -16,7 +16,7 @@ public static void main(String[] args) {
     }
 
     private static void printRandomDoubleUsingSupplier() {
-        DoubleSupplier doubleSupplier = () -> new Random().nextDouble();
+        DoubleSupplier doubleSupplier = () -> ThreadLocalRandom.current().nextDouble();
 
         System.out.println("Random double: " + doubleSupplier.getAsDouble());
     }

lambdas/src/main/java/com/bobocode/PredefinedInterfacesExamples.java

@@ -3,7 +3,7 @@
 import com.bobocode.data.Accounts;
 import com.bobocode.model.Account;
 
-import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.function.*;
 import java.util.stream.IntStream;
 
@@ -21,7 +21,7 @@ public static void main(String[] args) {
     }
 
     private static void printARandomNumberUsingIntegerSupplier() {
-        IntSupplier integerSupplier = () -> new Random().nextInt(1000);
+        IntSupplier integerSupplier = () -> ThreadLocalRandom.current().nextInt(1000);
 
         System.out.println("\nNext random value: " + integerSupplier.getAsInt());
     }
@@ -42,7 +42,7 @@ private static void calculate3xValueUsingIntegerFunction() {
 
     private static void checkIfNumberIsPositiveUsingIntegerPredicate() {
         IntPredicate isPositive = n -> n > 0;
-        int b = new Random().nextInt();
+        int b = ThreadLocalRandom.current().nextInt();
 
         System.out.println("\n" + b + " is " + (isPositive.test(b) ? "positive" : "negative"));
     }

optional/src/main/java/com/bobocode/OptionalReturningMethod.java

@@ -5,7 +5,7 @@
 
 import java.util.List;
 import java.util.Optional;
-import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 
 public class OptionalReturningMethod {
     public static void main(String[] args) {
@@ -20,8 +20,7 @@ public static void main(String[] args) {
      * as a returning-value in favor of null
      */
     private static Optional<Account> findLuckyGuy(List<Account> accounts) {
-        Random random = new Random();
-        int luckyIndex = random.nextInt(accounts.size() * 3);
+        int luckyIndex = ThreadLocalRandom.current().nextInt(accounts.size() * 3);
         if (luckyIndex < accounts.size()) {
             return Optional.of(accounts.get(luckyIndex));
         } else {