Makefile to compile both C and Java programs at the same time

Question

I have three programs that need to be compiled at the same time, 2 written in C and 1 in java. I had all three working with the Makefile when they were in C, but then rewrote one of them in java... is there a way to compile all 3 at once with the same makefile?

Here is my current Makefile:

CC=gcc 
JC=javac 
JFLAGS= -g
CFLAGS= -Wall -g -std=c99
LDFLAGS= -lm
.SUFFIXES: .java .class
.java.class:
 $(JC) $(JFLAGS) $*.java

CLASSES = kasiski.java kentry.java

ALL= ic ftable kasiski

all: $(ALL)

ic: ic.o

kasiski: $(CLASSES:.java=.class)

ftable: ftable.o

ic.o: ic.c ic.h

ftable.o: ftable.c ftable.h

.PHONY: clean

clean:
 rm -rf core* *.class *.o *.gch $(ALL)

Answer 1

Yes, you can compile them all at once. If your "all" target depends on all three applications, then "make all" should build all of them. You can throw in "-j3" to actually compile using three separate threads and/or processes (it isn't clear what you mean by "at once"). Also, a couple criticisms here:

• Do not define "CC", "CFLAGS", or "LDFLAGS". You should never define "CC" as it is automatically defined for you to the default C compiler on the system, and you should merely append to "CFLAGS" and "LDFLAGS" as needed (using +=) instead of clobbering them, as simply assigning to them makes your Makefile inflexible (because they cannot be overrided or augmented externally).
• Using CLASSES to refer to ".java" files is confusing as hell... you should probably rename the variable to JAVA_SRCS, and define JAVA_CLASSES=${JAVA_SRCS:.java=.class}.

For more explanation, please see my Makefile tutorial . That said, you may want to consider a more modern build system such as Bazel or Gradle . These systems are designed to be much simpler to use, less error prone, more portable (because they make it easier to do things portably), and faster.