edits & improvements

network/ChatterClient.java

@@ -4,7 +4,7 @@
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
 // {ValidateByHand}
 // Tests the ChatterServer by starting multiple
-// clients, each of which sends datagrams
+// clients, each of which sends datagrams.
 import java.net.*;
 import java.io.*;
 import onjava.*;
@@ -37,12 +37,11 @@ public class ChatterClient extends Thread {
   public void sendAndEcho(String msg) {
     try {
       // Make and send a datagram:
-      s.send(Dgram.toDatagram(msg,
+      s.send(Dgram.toDatagram(
-        hostAddress,
+        msg, hostAddress, ChatterServer.INPORT));
-        ChatterServer.INPORT));
       // Block until it echoes back:
       s.receive(dp);
-      // Print out the echoed contents:
+      // Display the echoed contents:
       String rcvd = "Client #" + id +
         ", rcvd from " +
         dp.getAddress() + ", " +

network/ChatterServer.java

@@ -31,7 +31,7 @@ public class ChatterServer {
           "Echoed: " + rcvd;
         // Extract the address and port from the
         // received datagram to find out where to
-        // send it back:
+        // send it back to:
         DatagramPacket echo =
           Dgram.toDatagram(echoString,
             dp.getAddress(), dp.getPort());

network/Dgram.java

@@ -2,8 +2,7 @@
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
-// Converts back and forth
+// Converts between Strings and DataGramPackets
-// between Strings and DataGramPackets
 import java.net.*;
 
 public class Dgram {

network/MultiSimpleClient.java

@@ -46,7 +46,9 @@ class SimpleClientThread extends Thread {
       // constructor:
       try {
         socket.close();
-      } catch(IOException e2) {}
+      } catch(IOException e2) {
+        throw new RuntimeException(e2);
+      }
     }
     // Otherwise the socket will be closed by
     // the run() method of the thread.
@@ -61,11 +63,14 @@ class SimpleClientThread extends Thread {
       }
       out.println("END");
     } catch(IOException e) {
+      throw new RuntimeException(e);
     } finally {
       // Always close it:
       try {
         socket.close();
-      } catch(IOException e) {}
+      } catch(IOException e) {
+        throw new RuntimeException(e);
+      }
       threadcount--; // Ending this thread
     }
   }
@@ -77,11 +82,9 @@ public class MultiSimpleClient {
   main(String[] args) throws IOException,
   InterruptedException {
     new TimedAbort(5); // Terminate after 5 seconds
-    InetAddress addr =
+    InetAddress addr = InetAddress.getByName(null);
-      InetAddress.getByName(null);
     while(true) {
-      if(SimpleClientThread.threadCount()
+      if(SimpleClientThread.threadCount() < MAX_THREADS)
-         < MAX_THREADS)
         new SimpleClientThread(addr);
       Thread.sleep(100);
     }

network/MultiSimpleServer.java

@@ -2,7 +2,7 @@
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
-// Uses multithreading to handle any number of clients
+// Uses threads to handle any number of clients
 // {ValidateByHand}
 import java.io.*;
 import java.net.*;
@@ -25,10 +25,9 @@ class ServeOneSimple extends Thread {
         new BufferedWriter(
           new OutputStreamWriter(
             socket.getOutputStream())), true);
-    // If any of the above calls throw an
+    // If any of the above calls throw an exception,
-    // exception, the caller is responsible for
+    // the caller is responsible for closing the
-    // closing the socket. Otherwise the thread
+    // socket. Otherwise the thread closes it.
-    // will close it.
     start(); // Calls run()
   }
   @Override
@@ -42,10 +41,13 @@ class ServeOneSimple extends Thread {
       }
       System.out.println("closing...");
     } catch (IOException e) {
+      throw new RuntimeException(e);
     } finally {
       try {
         socket.close();
-      } catch(IOException e) {}
+      } catch(IOException e) {
+        throw new RuntimeException(e);
+      }
     }
   }
 }

validating/CountedList.java

@@ -2,8 +2,7 @@
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
-// A List that keeps track of how many
+// Keeps track of how many of itself are created.
-// of itself are created.
 package validating;
 import java.util.*;
 

validating/CountedListTest.java

@@ -10,6 +10,14 @@ import static org.junit.jupiter.api.Assertions.*;
 
 public class CountedListTest {
   private CountedList list;
+  @BeforeAll
+  static void beforeAllMsg() {
+    System.out.println(">>> Starting CountedListTest");
+  }
+  @AfterAll
+  static void afterAllMsg() {
+    System.out.println(">>> Finished CountedListTest");
+  }
   @BeforeEach
   public void initialize() {
     list = new CountedList();
@@ -21,7 +29,6 @@ public class CountedListTest {
   public void cleanup() {
     System.out.println("Cleaning up " + list.getId());
   }
-  // All tests are marked with the @Test annotation:
   @Test
   public void insert() {
     System.out.println("Running testInsert()");
@@ -38,16 +45,12 @@ public class CountedListTest {
     assertEquals(list.size(), 3);
     assertEquals(list.get(1), "Replace");
   }
-  // A helper method to reduce code duplication. As long
+  // A helper method to simplify the code. As
-  // as it isn't annotated with @Test, it will not
+  // long as it isn't annotated with @Test, it will
-  // be automatically executed by JUnit.
+  // not be automatically executed by JUnit.
   private
   void compare(List<String> lst, String[] strs) {
-    String[] array = lst.toArray(new String[0]);
+    assertArrayEquals(lst.toArray(new String[0]), strs);
-    assertTrue(array.length == strs.length,
-      "Arrays not the same length");
-    for(int i = 0; i < array.length; i++)
-      assertEquals(strs[i], array[i]);
   }
   @Test
   public void order() {
@@ -72,15 +75,3 @@ public class CountedListTest {
        "An", "African", "Swallow" });
   }
 }
-/* Output:
-CountedList #0
-Running testAddAll()
-CountedList #1
-Running testInsert()
-CountedList #2
-Running testRemove()
-CountedList #3
-Running testOrder()
-CountedList #4
-Running testReplace()
-*/

validating/DynamicStringInverterTests.java

@@ -22,13 +22,14 @@ class DynamicStringInverterTests {
       inverter -> inverter.getClass().getSimpleName(),
       inverter -> {
         System.out.println(
-          inverter.getClass().getSimpleName() + ": " + id
+          inverter.getClass().getSimpleName() +
-        );
+            ": " + id);
         try {
           if(test.apply(inverter) != "fail")
             System.out.println("Success");
         } catch(Exception | Error e) {
-          System.out.println("Exception: " + e.getMessage());
+          System.out.println(
+            "Exception: " + e.getMessage());
         }
       }
     );

validating/FirstJUnit5Tests.java

@@ -1,15 +0,0 @@
-// validating/FirstJUnit5Tests.java
-// (c)2016 MindView LLC: see Copyright.txt
-// We make no guarantees that this code is fit for any purpose.
-// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
-package validating;
-import org.junit.jupiter.api.*;
-import static org.junit.jupiter.api.Assertions.*;
-
-class FirstJUnit5Tests {
-  @Test
-  void myFirstTest() {
-    System.out.println("FirstJUnit5Tests");
-    assertEquals(2, 1 + 1);
-  }
-}

validating/GuavaAssertions.java

@@ -0,0 +1,48 @@
+// validating/GuavaAssertions.java
+// (c)2016 MindView LLC: see Copyright.txt
+// We make no guarantees that this code is fit for any purpose.
+// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
+// Assertions that are always enabled.
+import com.google.common.base.*;
+import static com.google.common.base.Verify.*;
+
+public class GuavaAssertions {
+  public static void main(String[] args) {
+    verify(2 + 2 == 4);
+    try {
+      verify(1 + 2 == 4);
+    } catch(VerifyException e) {
+      System.out.println(e);
+    }
+    try {
+      verify(1 + 2 == 4, "Bad math");
+    } catch(VerifyException e) {
+      System.out.println(e.getMessage());
+    }
+    try {
+      verify(1 + 2 == 4, "Bad math: %s", "not 4");
+    } catch(VerifyException e) {
+      System.out.println(e.getMessage());
+    }
+    String s = "";
+    s = verifyNotNull(s);
+    s = null;
+    try {
+      verifyNotNull(s);
+    } catch(VerifyException e) {
+      System.out.println(e.getMessage());
+    }
+    try {
+      verifyNotNull(s, "Shouldn't be null: %s", "arg s");
+    } catch(VerifyException e) {
+      System.out.println(e.getMessage());
+    }
+  }
+}
+/* Output:
+com.google.common.base.VerifyException
+Bad math
+Bad math: not 4
+expected a non-null reference
+Shouldn't be null: arg s
+*/

validating/GuavaPreconditions.java

@@ -3,12 +3,121 @@
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
 // Demonstrating Guava Preconditions
+import java.util.function.*;
 import static com.google.common.base.Preconditions.*;
 
 public class GuavaPreconditions {
-
+  void g(String s) {
+    checkState(s.length() > 6);
+    System.out.println("Success: " + s);
+  }
+  static void test(Consumer<String> c, String s) {
+    try {
+      System.out.println(s);
+      c.accept(s);
+      System.out.println("Success");
+    } catch(Exception e) {
+      String type = e.getClass().getSimpleName();
+      String msg = e.getMessage();
+      System.out.println(type +
+        (msg == null ? "" : ": " + msg));
+    }
+  }
   public static void main(String[] args) {
+    test((s) -> s = checkNotNull(s), "X");
+    test((s) -> s = checkNotNull(s), null);
+    test((s) -> s = checkNotNull(s, "s was null"), null);
+    test((s) -> s = checkNotNull(
+      s, "s was null, %s %s", "arg2", "arg3"), null);
+
+    test((s) -> checkArgument(s == "Fozzie"), "Fozzie");
+    test((s) -> checkArgument(s == "Fozzie"), "X");
+    test((s) -> checkArgument(s == "Fozzie"), null);
+    test((s) -> checkArgument(
+      s == "Fozzie", "Bear Left!"), null);
+    test((s) -> checkArgument(
+      s == "Fozzie", "Bear Left! %s Right!", "Frog"),
+      null);
+
+    test((s) -> checkState(s.length() > 6), "Mortimer");
+    test((s) -> checkState(s.length() > 6), "Mort");
+    test((s) -> checkState(s.length() > 6), null);
+
+    test((s) ->
+      checkElementIndex(6, s.length()), "Robert");
+    test((s) ->
+      checkElementIndex(6, s.length()), "Bob");
+    test((s) ->
+      checkElementIndex(6, s.length()), null);
+
+    test((s) ->
+      checkPositionIndex(6, s.length()), "Robert");
+    test((s) ->
+      checkPositionIndex(6, s.length()), "Bob");
+    test((s) ->
+      checkPositionIndex(6, s.length()), null);
+
+    test((s) -> checkPositionIndexes(
+      0, 6, s.length()), "Hieronymus");
+    test((s) -> checkPositionIndexes(
+      0, 10, s.length()), "Hieronymus");
+    test((s) -> checkPositionIndexes(
+      0, 11, s.length()), "Hieronymus");
+    test((s) -> checkPositionIndexes(
+      -1, 6, s.length()), "Hieronymus");
+    test((s) -> checkPositionIndexes(
+      7, 6, s.length()), "Hieronymus");
+    test((s) -> checkPositionIndexes(
+      0, 6, s.length()), null);
   }
 }
 /* Output:
+X
+Success
+null
+NullPointerException
+null
+NullPointerException: s was null
+null
+NullPointerException: s was null, arg2 arg3
+Fozzie
+Success
+X
+IllegalArgumentException
+null
+IllegalArgumentException
+null
+IllegalArgumentException: Bear Left!
+null
+IllegalArgumentException: Bear Left! Frog Right!
+Mortimer
+Success
+Mort
+IllegalStateException
+null
+NullPointerException
+Robert
+IndexOutOfBoundsException: index (6) must be less than size (6)
+Bob
+IndexOutOfBoundsException: index (6) must be less than size (3)
+null
+NullPointerException
+Robert
+Success
+Bob
+IndexOutOfBoundsException: index (6) must not be greater than size (3)
+null
+NullPointerException
+Hieronymus
+Success
+Hieronymus
+Success
+Hieronymus
+IndexOutOfBoundsException: end index (11) must not be greater than size (10)
+Hieronymus
+IndexOutOfBoundsException: start index (-1) must not be negative
+Hieronymus
+IndexOutOfBoundsException: end index (6) must not be less than start index (7)
+null
+NullPointerException
 */