Rework Java Makefile

Makefile

@@ -4,7 +4,7 @@ help:
 	@echo "  - Prerequisite: third_party third_party_check clean_third_party"
 	@echo "  - C++: cc test_cc clean_cc"
 	@echo "  - Python: python help_python test_python clean_python"
-	@echo "  - Java: java test_java clean_java"
+	@echo "  - Java: java help_java test_java clean_java"
 	@echo "  - .NET (CSharp): csharp test_csharp clean_csharp"
 	@echo "  - .NET (FSharp): fsharp fsharp-help fsharp-clean"
 	@echo "  - all: all test clean"
@@ -30,9 +30,11 @@ else
   endif
 endif
 
-.PHONY : help detect cc python java csharp sat third_party_check
+.PHONY : help cc python java csharp sat third_party_check
 all: third_party_check cc java python csharp
 	@echo Or-tools have been built for $(BUILT_LANGUAGES)
+
+.PHONY: clean
 clean: clean_cc clean_java clean_python clean_csharp clean_compat
 
 # Read version.
@@ -74,4 +76,7 @@ ifeq ($(wildcard dependencies/install/include/gflags/gflags.h),)
 	@echo "One of the third party files was not found! did you run 'make third_party'?" && exit 1
 endif
 
+.PHONY: detect
+detect: detect_port detect_python detect_java detect_csharp
+
 print-%  : ; @echo $* = $($*)

makefiles/Makefile.java.mk

@@ -1,6 +1,10 @@
 # ---------- Java support using SWIG ----------
+.PHONY: help_java # Generate list of targets with descriptions.
+help_java:
+	@echo Use one of the following targets:
+	@grep "^.PHONY: .* #" $(CURDIR)/makefiles/Makefile.java.mk | sed "s/\.PHONY: \(.*\) # \(.*\)/\1\t\2/" | expand -t24
 
-.PHONY: java rjava cjava
+.PHONY: rjava cjava
 
 JAVA_ORTOOLS_LIBS= $(LIB_DIR)/com.google.ortools.jar $(LIB_DIR)/$(LIB_PREFIX)jniortools.$(JNI_LIB_EXT)
 
@@ -374,25 +378,21 @@ endif
 endif # ifeq ($(EX),)
 
 # Main target
+.PHONY: java # Build Java OR-Tools.
+.PHONY: test_java # Test Java OR-Tools using various examples.
 CANONIC_JDK_DIRECTORY = $(subst $(SPACE),$(BACKSLASH_SPACE),$(subst \,/,$(subst \\,/,$(JDK_DIRECTORY))))
 ifeq ($(wildcard $(CANONIC_JDK_DIRECTORY)),)
 java:
-	@echo "The java executable was not set properly. Check Makefile.local for more information."
+	$@echo JAVA_BIN = ${JAVA_BIN}
+	$(warning Cannot find 'java' command which is needed for build. Please make sure it is installed and in system path. Check Makefile.local for more information.)
 test_java: java
 else
 java: $(JAVA_ORTOOLS_LIBS)
 test_java: test_java_examples
-BUILT_LANGUAGES +=, java
+BUILT_LANGUAGES +=, Java
 endif
 
-detect_java:
-	@echo JDK_DIRECTORY = $(JDK_DIRECTORY)
-	@echo JAVA_BIN = $(JAVA_BIN)
-	@echo JAVA_INC = $(JAVA_INC)
-	@echo JAVAC_BIN = $(JAVAC_BIN)
-	@echo JAR_BIN = $(JAR_BIN)
-
-# Clean target
+.PHONY: clean_java # Clean Java output from previous build.
 clean_java:
 	-$(DEL) $(LIB_DIR)$S$(LIB_PREFIX)jni*.$(JNI_LIB_EXT)
 	-$(DEL) $(LIB_DIR)$S*.jar
@@ -410,3 +410,11 @@ clean_java:
 	-$(DEL) $(OBJ_DIR)$Scom$Sgoogle$Sortools$Slinearsolver$S*.class
 	-$(DEL) $(OBJ_DIR)$Scom$Sgoogle$Sortools$Ssamples$S*.class
 	-$(DEL) $(OBJ_DIR)$Sswig$S*java_wrap.$O
+
+.PHONY: detect_java # Show variables used to build Java OR-Tools.
+detect_java:
+	@echo JDK_DIRECTORY = $(JDK_DIRECTORY)
+	@echo JAVA_BIN = $(JAVA_BIN)
+	@echo JAVA_INC = $(JAVA_INC)
+	@echo JAVAC_BIN = $(JAVAC_BIN)
+	@echo JAR_BIN = $(JAR_BIN)