[#1915] improve default provider examples

picocli-examples/src/main/java/picocli/examples/defaultprovider/SimpleDefaultProviderDemo.java

@@ -0,0 +1,55 @@
+package picocli.examples.defaultprovider;
+
+import picocli.CommandLine;
+import picocli.CommandLine.Command;
+import picocli.CommandLine.IDefaultValueProvider;
+import picocli.CommandLine.Model.ArgSpec;
+import picocli.CommandLine.Model.OptionSpec;
+import picocli.CommandLine.Option;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.Reader;
+import java.util.Properties;
+import java.util.concurrent.TimeUnit;
+
+@Command(name = "demo", mixinStandardHelpOptions = true, version = CommandLine.VERSION,
+        description = "Demonstrates default provider",
+        defaultValueProvider = SimpleDefaultProvider.class)
+public class SimpleDefaultProviderDemo implements Runnable { // ...
+
+    @Option(names = "-x", description = "Print count. ${DEFAULT-VALUE} by default.")
+    int x;
+
+    @Option(names = "-d") double d;
+    @Option(names = { "-u", "--timeUnit"}) TimeUnit unit;
+
+    @Override
+    public void run() {
+        for (int i = 0; i < x; i++) {
+            System.out.printf("You selected %f, %s.%n", d, unit);
+        }
+    }
+
+    public static void main(String[] args) {
+        new CommandLine(new SimplePropertyDefaultProviderDemo()).execute(args);
+    }
+}
+
+class SimpleDefaultProvider implements IDefaultValueProvider {
+
+    @Override
+    public String defaultValue(ArgSpec argSpec) throws Exception {
+
+        if (argSpec.isOption()) {
+            OptionSpec option = (OptionSpec) argSpec;
+            if ("--timeUnit".equals(option.longestName())) {
+                return TimeUnit.SECONDS.name();
+            }
+            if ("-x".equals(option.longestName())) {
+                return "3";
+            }
+        }
+        return null;
+    }
+}

picocli-examples/src/main/java/picocli/examples/defaultprovider/SimplePropertyDefaultProviderDemo.java

@@ -15,7 +15,7 @@
 
 @Command(name = "demo", mixinStandardHelpOptions = true, version = "3.9.3",
         description = "Demonstrate parsing & type conversion",
-        defaultValueProvider = PropertyDefaultProvider.class)
+        defaultValueProvider = SimpleDefaultProvider.class)
 public class SimplePropertyDefaultProviderDemo implements Runnable { // ...
 
     @Option(names = "-x", description = "Print count. ${DEFAULT-VALUE} by default.")