Java 11 migration: patterns (t-v) (#1085)

* Moves visitor pattern to java 11

* Moves value-object pattern to java 11

* Moves unit-of-work pattern to java 11

* Moves typeobjectpattern pattern to java 11

* Moves twin pattern to java 11

* Moves trampoline pattern to java 11

* Moves tolerant-reader pattern to java 11

* Moves tls pattern to java 11

* Moves throttling pattern to java 11

* Moves thread-pool pattern to java 11

* Moves template-method pattern to java 11

tls/src/main/java/com/iluwatar/tls/App.java

@@ -24,10 +24,7 @@
 package com.iluwatar.tls;
 
 import java.util.Calendar;
-import java.util.Date;
-import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-import java.util.concurrent.Future;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -71,20 +68,20 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-    int counterDateValues = 0;
-    int counterExceptions = 0;
+    var counterDateValues = 0;
+    var counterExceptions = 0;
 
     // Create a callable
-    DateFormatCallable callableDf = new DateFormatCallable("dd/MM/yyyy", "15/12/2015");
+    var callableDf = new DateFormatCallable("dd/MM/yyyy", "15/12/2015");
     // start 4 threads, each using the same Callable instance
-    ExecutorService executor = Executors.newCachedThreadPool();
+    var executor = Executors.newCachedThreadPool();
 
-    Future<Result> futureResult1 = executor.submit(callableDf);
-    Future<Result> futureResult2 = executor.submit(callableDf);
-    Future<Result> futureResult3 = executor.submit(callableDf);
-    Future<Result> futureResult4 = executor.submit(callableDf);
+    var futureResult1 = executor.submit(callableDf);
+    var futureResult2 = executor.submit(callableDf);
+    var futureResult3 = executor.submit(callableDf);
+    var futureResult4 = executor.submit(callableDf);
     try {
-      Result[] result = new Result[4];
+      var result = new Result[4];
       result[0] = futureResult1.get();
       result[1] = futureResult2.get();
       result[2] = futureResult3.get();
@@ -92,9 +89,9 @@ public class App {
 
       // Print results of thread executions (converted dates and raised exceptions)
       // and count them
-      for (int i = 0; i < result.length; i++) {
-        counterDateValues = counterDateValues + printAndCountDates(result[i]);
-        counterExceptions = counterExceptions + printAndCountExceptions(result[i]);
+      for (var value : result) {
+        counterDateValues = counterDateValues + printAndCountDates(value);
+        counterExceptions = counterExceptions + printAndCountExceptions(value);
       }
 
       // a correct run should deliver 20 times 15.12.2015
@@ -115,15 +112,16 @@ public class App {
    */
   private static int printAndCountDates(Result res) {
     // a correct run should deliver 5 times 15.12.2015 per each thread
-    int counter = 0;
-    for (Date dt : res.getDateList()) {
+    var counter = 0;
+    for (var dt : res.getDateList()) {
       counter++;
-      Calendar cal = Calendar.getInstance();
+      var cal = Calendar.getInstance();
       cal.setTime(dt);
       // Formatted output of the date value: DD.MM.YYYY
-      LOGGER.info(
-          cal.get(Calendar.DAY_OF_MONTH) + "." + cal.get(Calendar.MONTH) + "." + +cal
-              .get(Calendar.YEAR));
+      LOGGER.info(cal.get(Calendar.DAY_OF_MONTH) + "."
+          + cal.get(Calendar.MONTH) + "."
+          + cal.get(Calendar.YEAR)
+      );
     }
     return counter;
   }
@@ -136,8 +134,8 @@ public class App {
    */
   private static int printAndCountExceptions(Result res) {
     // a correct run shouldn't deliver any exception
-    int counter = 0;
-    for (String ex : res.getExceptionList()) {
+    var counter = 0;
+    for (var ex : res.getExceptionList()) {
       counter++;
       LOGGER.info(ex);
     }

tls/src/main/java/com/iluwatar/tls/DateFormatCallable.java

@@ -26,6 +26,7 @@ package com.iluwatar.tls;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.concurrent.Callable;
+import java.util.stream.IntStream;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -58,13 +59,10 @@ public class DateFormatCallable implements Callable<Result> {
    * @param inDateValue  string date value, e.g. "21/06/2016"
    */
   public DateFormatCallable(String inDateFormat, String inDateValue) {
-    final String idf = inDateFormat;                 //TLTL
-    this.df = new ThreadLocal<DateFormat>() {        //TLTL
-      @Override                                      //TLTL
-      protected DateFormat initialValue() {          //TLTL
-        return new SimpleDateFormat(idf);            //TLTL
-      }                                              //TLTL
-    };                                               //TLTL
+    final var idf = inDateFormat;                 //TLTL
+    this.df = ThreadLocal.withInitial(() -> {          //TLTL
+      return new SimpleDateFormat(idf);            //TLTL
+    });                                               //TLTL
     // this.df = new SimpleDateFormat(inDateFormat);    //NTLNTL
     this.dateValue = inDateValue;
   }
@@ -72,10 +70,10 @@ public class DateFormatCallable implements Callable<Result> {
   @Override
   public Result call() {
     LOGGER.info(Thread.currentThread() + " started executing...");
-    Result result = new Result();
+    var result = new Result();
 
     // Convert date value to date 5 times
-    for (int i = 1; i <= 5; i++) {
+    IntStream.rangeClosed(1, 5).forEach(i -> {
       try {
         // this is the statement where it is important to have the
         // instance of SimpleDateFormat locally
@@ -86,8 +84,7 @@ public class DateFormatCallable implements Callable<Result> {
         // write the Exception to a list and continue work
         result.getExceptionList().add(e.getClass() + ": " + e.getMessage());
       }
-
-    }
+    });
 
     LOGGER.info(Thread.currentThread() + " finished processing part of the thread");
 

tls/src/main/java/com/iluwatar/tls/Result.java

@@ -39,11 +39,11 @@ import java.util.List;
  */
 public class Result {
   // A list to collect the date values created in one thread
-  private List<Date> dateList = new ArrayList<Date>();
+  private List<Date> dateList = new ArrayList<>();
 
   // A list to collect Exceptions thrown in one threads (should be none in
   // this example)
-  private List<String> exceptionList = new ArrayList<String>();
+  private List<String> exceptionList = new ArrayList<>();
 
   /**
    * Get list of date values collected within a thread execution.