add const printing utility

src/main/java/org/cobbzilla/util/main/ConstMain.java

@@ -0,0 +1,38 @@
+package org.cobbzilla.util.main;
+
+import static org.cobbzilla.util.daemon.ZillaRuntime.shortError;
+import static org.cobbzilla.util.reflect.ReflectionUtil.constValue;
+import static org.cobbzilla.util.reflect.ReflectionUtil.forName;
+
+/**
+ * Write a constant value to stdout.
+ *
+ * This will only ever write the constant value to stdout if it can successfully be read.
+ * If the constant can be read, its value is printed with the .toString() method.
+ * If an error occurs, nothing is written to stdout, and the error will be written to stderr.
+ * If the value of the constant is null, nothing is printed to stdout, and "null" is printed to stderr.
+ */
+public class ConstMain extends BaseMain<ConstOptions> {
+
+    public static void main(String[] args) { main(ConstMain.class, args); }
+
+    @Override protected void run() throws Exception {
+        final String cm = getOptions().getClassAndMember();
+        final int lastDot = cm.lastIndexOf('.');
+        if (lastDot == -1 || lastDot == cm.length()-1) {
+            die("invalid value: "+cm);
+        } else {
+            try {
+                final Object val = constValue(forName(cm.substring(0, lastDot)), cm.substring(lastDot + 1));
+                if (val == null) {
+                    err("null");
+                } else {
+                    out(val.toString());
+                }
+            } catch (Exception e) {
+                die("Exception getting constant value "+cm+": "+shortError(e), e);
+            }
+        }
+    }
+
+}

src/main/java/org/cobbzilla/util/main/ConstOptions.java

@@ -0,0 +1,13 @@
+package org.cobbzilla.util.main;
+
+import lombok.Getter;
+import lombok.Setter;
+import org.kohsuke.args4j.Argument;
+
+public class ConstOptions extends BaseMainOptions {
+
+    public static final String USAGE_CLASS_AND_MEMBER = "Specify a class.member constant";
+    @Argument(usage=USAGE_CLASS_AND_MEMBER, required=true)
+    @Getter @Setter private String classAndMember;
+
+}