rewrite to use var, instanceof with type test pattern, switch expression

and record

Author: forax

src/effectivejava/chapter11/item78/brokenstopthread/StopThread.java

@@ -7,8 +7,8 @@ public class StopThread {
 
     public static void main(String[] args)
             throws InterruptedException {
-        Thread backgroundThread = new Thread(() -> {
-            int i = 0;
+        var backgroundThread = new Thread(() -> {
+            var i = 0;
             while (!stopRequested)
                 i++;
         });

src/effectivejava/chapter11/item78/fixedstopthread1/StopThread.java

@@ -15,8 +15,8 @@ private static synchronized boolean stopRequested() {
 
     public static void main(String[] args)
             throws InterruptedException {
-        Thread backgroundThread = new Thread(() -> {
-            int i = 0;
+        var backgroundThread = new Thread(() -> {
+            var i = 0;
             while (!stopRequested())
                 i++;
         });

src/effectivejava/chapter11/item78/fixedstopthread2/StopThread.java

@@ -7,8 +7,8 @@ public class StopThread {
 
     public static void main(String[] args)
             throws InterruptedException {
-        Thread backgroundThread = new Thread(() -> {
-            int i = 0;
+        var backgroundThread = new Thread(() -> {
+            var i = 0;
             while (!stopRequested)
                 i++;
         });

src/effectivejava/chapter11/item79/ObservableSet.java

@@ -39,7 +39,7 @@ public class ObservableSet<E> extends ForwardingSet<E> {
 //    }
 
     // Thread-safe observable set with CopyOnWriteArrayList
-    private final List<SetObserver<E>> observers =
+    private final CopyOnWriteArrayList<SetObserver<E>> observers =
             new CopyOnWriteArrayList<>();
 
     public void addObserver(SetObserver<E> observer) {
@@ -51,20 +51,20 @@ public boolean removeObserver(SetObserver<E> observer) {
     }
 
     private void notifyElementAdded(E element) {
-        for (SetObserver<E> observer : observers)
+        for (var observer : observers)
             observer.added(this, element);
     }
 
     @Override public boolean add(E element) {
-        boolean added = super.add(element);
+        var added = super.add(element);
         if (added)
             notifyElementAdded(element);
         return added;
     }
 
     @Override public boolean addAll(Collection<? extends E> c) {
-        boolean result = false;
-        for (E element : c)
+        var result = false;
+        for (var element : c)
             result |= add(element);  // Calls notifyElementAdded
         return result;
     }

src/effectivejava/chapter11/item79/Test1.java

@@ -4,12 +4,12 @@
 // Simple test of ObservableSet - Page 318
 public class Test1 {
     public static void main(String[] args) {
-        ObservableSet<Integer> set =
-                new ObservableSet<>(new HashSet<>());
+        var set =
+                new ObservableSet<>(new HashSet<Integer>());
 
         set.addObserver((s, e) -> System.out.println(e));
 
-        for (int i = 0; i < 100; i++)
+        for (var i = 0; i < 100; i++)
             set.add(i);
     }
 }

src/effectivejava/chapter11/item79/Test2.java

@@ -4,8 +4,8 @@
 // More complex test of ObservableSet - Page 318-9
 public class Test2 {
     public static void main(String[] args) {
-        ObservableSet<Integer> set =
-                new ObservableSet<>(new HashSet<>());
+        var set =
+                new ObservableSet<>(new HashSet<Integer>());
 
         set.addObserver(new SetObserver<>() {
             public void added(ObservableSet<Integer> s, Integer e) {
@@ -15,7 +15,7 @@ public void added(ObservableSet<Integer> s, Integer e) {
             }
         });
 
-        for (int i = 0; i < 100; i++)
+        for (var i = 0; i < 100; i++)
             set.add(i);
     }
 }

src/effectivejava/chapter11/item79/Test3.java

@@ -7,16 +7,15 @@
 // Simple test of ObservableSet - Page 319
 public class Test3 {
     public static void main(String[] args) {
-        ObservableSet<Integer> set =
-                new ObservableSet<>(new HashSet<>());
+        var set =
+                new ObservableSet<>(new HashSet<Integer>());
 
 // Observer that uses a background thread needlessly
         set.addObserver(new SetObserver<>() {
             public void added(ObservableSet<Integer> s, Integer e) {
                 System.out.println(e);
                 if (e == 23) {
-                    ExecutorService exec =
-                            Executors.newSingleThreadExecutor();
+                    var exec = Executors.newSingleThreadExecutor();
                     try {
                         exec.submit(() -> s.removeObserver(this)).get();
                     } catch (ExecutionException | InterruptedException ex) {
@@ -28,7 +27,7 @@ public void added(ObservableSet<Integer> s, Integer e) {
             }
         });
 
-        for (int i = 0; i < 100; i++)
+        for (var i = 0; i < 100; i++)
             set.add(i);
     }
 }

src/effectivejava/chapter11/item81/ConcurrentTimer.java

@@ -7,11 +7,11 @@ private ConcurrentTimer() { } // Noninstantiable
 
     public static long time(Executor executor, int concurrency,
                             Runnable action) throws InterruptedException {
-        CountDownLatch ready = new CountDownLatch(concurrency);
-        CountDownLatch start = new CountDownLatch(1);
-        CountDownLatch done  = new CountDownLatch(concurrency);
+        var ready = new CountDownLatch(concurrency);
+        var start = new CountDownLatch(1);
+        var done  = new CountDownLatch(concurrency);
 
-        for (int i = 0; i < concurrency; i++) {
+        for (var i = 0; i < concurrency; i++) {
             executor.execute(() -> {
                 ready.countDown(); // Tell timer we're ready
                 try {
@@ -26,7 +26,7 @@ public static long time(Executor executor, int concurrency,
         }
 
         ready.await();     // Wait for all workers to be ready
-        long startNanos = System.nanoTime();
+        var startNanos = System.nanoTime();
         start.countDown(); // And they're off!
         done.await();      // Wait for all workers to finish
         return System.nanoTime() - startNanos;

src/effectivejava/chapter11/item81/Intern.java

@@ -8,13 +8,13 @@ public class Intern {
             new ConcurrentHashMap<>();
 
 //    public static String intern(String s) {
-//        String previousValue = map.putIfAbsent(s, s);
+//        var previousValue = map.putIfAbsent(s, s);
 //        return previousValue == null ? s : previousValue;
 //    }
 
     // Concurrent canonicalizing map atop ConcurrentMap - faster!
     public static String intern(String s) {
-        String result = map.get(s);
+        var result = map.get(s);
         if (result == null) {
             result = map.putIfAbsent(s, s);
             if (result == null)

src/effectivejava/chapter11/item83/Initialization.java

@@ -27,7 +27,7 @@ private static class FieldHolder {
 
     // NOTE: The code for this method in the first printing had a serious error (see errata for details)!
     private FieldType getField4() {
-        FieldType result = field4;
+        var result = field4;
         if (result != null)    // First check (no locking)
             return result;
 
@@ -44,7 +44,7 @@ private FieldType getField4() {
     private volatile FieldType field5;
 
     private FieldType getField5() {
-        FieldType result = field5;
+        var result = field5;
         if (result == null)
             field5 = result = computeFieldValue();
         return result;