added some exercise files and fixed misprints

java/src/main/java/lesson01/README.md

@@ -30,7 +30,6 @@ public class Hello {
         }
         String helloTo = args[0];
         new Hello().sayHello(helloTo);
-        tracer.close();
     }
 }
 ```
@@ -79,6 +78,7 @@ public class Hello {
         }
         String helloTo = args[0];
         new Hello(GlobalTracer.get()).sayHello(helloTo);
+        tracer.close();
     }
 }
 ```
@@ -137,10 +137,10 @@ the tracer as originating from a `hello-world` service.
 If we run the program now, we should see a span logged:
 
 ```
-$ ./run.sh lesson01.exercise.Hello Bryan
-[lesson01.exercise.Hello.main()] INFO com.uber.jaeger.Configuration - Initialized tracer=Tracer(...)
+$ ./run.sh lesson01.solution.Hello Bryan
+[lesson01.solution.Hello.main()] INFO com.uber.jaeger.Configuration - Initialized tracer=Tracer(...)
 Hello, Bryan!
-[lesson01.exercise.Hello.main()] INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: 76509ca0cd333055:76509ca0cd333055:0:1 - say-hello
+[lesson01.solution.Hello.main()] INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: 76509ca0cd333055:76509ca0cd333055:0:1 - say-hello
 ```
 
 If you have Jaeger backend running, you should be able to see the trace in the UI.

java/src/main/java/lesson01/exercise/Hello.java

@@ -0,0 +1,17 @@
+package lesson01.exercise;
+
+public class Hello {
+
+    private void sayHello(String helloTo) {
+        String helloStr = String.format("Hello, %s!", helloTo);
+        System.out.println(helloStr);
+    }
+
+    public static void main(String[] args) {
+        if (args.length != 1) {
+            throw new IllegalArgumentException("Expecting one argument");
+        }
+        String helloTo = args[0];
+        new Hello().sayHello(helloTo);
+    }
+}

java/src/main/java/lesson01/solution/Hello.java

@@ -2,8 +2,10 @@
 
 import io.opentracing.Span;
 import com.google.common.collect.ImmutableMap;
+import com.uber.jaeger.Configuration;
+import com.uber.jaeger.Configuration.ReporterConfiguration;
+import com.uber.jaeger.Configuration.SamplerConfiguration;
 import com.uber.jaeger.Tracer;
-import lib.Tracing;
 
 public class Hello {
 
@@ -31,8 +33,15 @@ public static void main(String[] args) {
             throw new IllegalArgumentException("Expecting one argument");
         }
         String helloTo = args[0];
-        Tracer tracer = Tracing.init("hello-world");
+        Tracer tracer = initTracer("hello-world");
         new Hello(tracer).sayHello(helloTo);
         tracer.close();
     }
+
+    public static com.uber.jaeger.Tracer initTracer(String service) {
+        SamplerConfiguration samplerConfig = new SamplerConfiguration("const", 1);
+        ReporterConfiguration reporterConfig = new ReporterConfiguration(true, null, null, null, null);
+        Configuration config = new Configuration(service, samplerConfig, reporterConfig);
+        return (com.uber.jaeger.Tracer) config.getTracer();
+    }
 }

java/src/main/java/lesson02/exercise/Hello.java

@@ -0,0 +1,56 @@
+package lesson02.exercise;
+
+import io.opentracing.Span;
+import com.google.common.collect.ImmutableMap;
+import com.uber.jaeger.Tracer;
+import lib.Tracing;
+
+public class Hello {
+
+    private final Tracer tracer;
+
+    private Hello(Tracer tracer) {
+        this.tracer = tracer;
+    }
+
+    private void sayHello(String helloTo) {
+        Span span = tracer.buildSpan("say-hello").startManual();
+        span.setTag("hello-to", helloTo);
+
+        String helloStr = formatString(span, helloTo);
+        printHello(span, helloStr);
+
+        span.finish();
+    }
+
+    private  String formatString(Span rootSpan, String helloTo) {
+        Span span = tracer.buildSpan("formatString").startManual();
+        try {
+            String helloStr = String.format("Hello, %s!", helloTo);
+            span.log(ImmutableMap.of("event", "string-format", "value", helloStr));
+            return helloStr;
+        } finally {
+            span.finish();
+        }
+    }
+
+    private void printHello(Span rootSpan, String helloStr) {
+        Span span = tracer.buildSpan("printHello").startManual();
+        try {
+            System.out.println(helloStr);
+            span.log(ImmutableMap.of("event", "println"));
+        } finally {
+            span.finish();
+        }
+    }
+
+    public static void main(String[] args) {
+        if (args.length != 1) {
+            throw new IllegalArgumentException("Expecting one argument");
+        }
+        String helloTo = args[0];
+        Tracer tracer = Tracing.init("hello-world");
+        new Hello(tracer).sayHello(helloTo);
+        tracer.close();
+    }
+}

java/src/main/java/lesson03/README.md

@@ -199,25 +199,25 @@ public String format(@QueryParam("helloTo") String helloTo, @Context HttpHeaders
 ### Take It For a Spin
 
 As before, first run the `formatter` and `publisher` apps in separate terminals.
-Then run `lesson03.exercise.Hello`. You should see the outputs like this:
+Then run `lesson03.solution.Hello`. You should see the outputs like this:
 
 ```
 # client
-$ ./run.sh lesson03.exercise.Hello Bryan
+$ ./run.sh lesson03.solution.Hello Bryan
 INFO com.uber.jaeger.Configuration - Initialized tracer=Tracer(...)
 INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: 5fe2d9de96c3887a:72910f6018b1bd09:5fe2d9de96c3887a:1 - formatString
 INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: 5fe2d9de96c3887a:62d73167c129ecd7:5fe2d9de96c3887a:1 - printHello
 INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: 5fe2d9de96c3887a:5fe2d9de96c3887a:0:1 - say-hello
 
 # formatter
-$ ./run.sh lesson03.exercise.Formatter server
+$ ./run.sh lesson03.solution.Formatter server
 [skip noise]
 INFO org.eclipse.jetty.server.Server: Started @3968ms
 INFO com.uber.jaeger.reporters.LoggingReporter: Span reported: 5fe2d9de96c3887a:b73ff97ea68a36f8:72910f6018b1bd09:1 - format
 127.0.0.1 - - "GET /format?helloTo=Bryan HTTP/1.1" 200 13 "-" "okhttp/3.9.0" 3
 
 # publisher
-$ ./run.sh lesson03.exercise.Publisher server
+$ ./run.sh lesson03.solution.Publisher server
 [skip noise]
 INFO org.eclipse.jetty.server.Server: Started @3388ms
 Hello, Bryan!

java/src/main/java/lesson04/README.md

@@ -69,21 +69,21 @@ with two arguments, e.g. `Bryan Bonjour`. The `publisher` should print `Bonjour,
 
 ```
 # client
-$ ./run.sh lesson04.exercise.Hello Bryan Bonjour
+$ ./run.sh lesson04.solution.Hello Bryan Bonjour
 INFO com.uber.jaeger.Configuration - Initialized tracer=Tracer(...)
 INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: e6ee8a816c8386ce:ef06ddba375ff053:e6ee8a816c8386ce:1 - formatString
 INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: e6ee8a816c8386ce:20cdfed1d23892c1:e6ee8a816c8386ce:1 - printHello
 INFO com.uber.jaeger.reporters.LoggingReporter - Span reported: e6ee8a816c8386ce:e6ee8a816c8386ce:0:1 - say-hello
 
 # formatter
-$ ./run.sh lesson04.exercise.Formatter server
+$ ./run.sh lesson04.solution.Formatter server
 [skip noise]
 INFO org.eclipse.jetty.server.Server: Started @3508ms
 INFO com.uber.jaeger.reporters.LoggingReporter: Span reported: e6ee8a816c8386ce:cd2c1d243ddf319b:ef06ddba375ff053:1 - format
 127.0.0.1 - - "GET /format?helloTo=Bryan HTTP/1.1" 200 15 "-" "okhttp/3.9.0" 69
 
 # publisher
-$ ./run.sh lesson03.exercise.Publisher server
+$ ./run.sh lesson03.solution.Publisher server
 [skip noise]
 INFO org.eclipse.jetty.server.Server: Started @3388ms
 Bonjour, Bryan!