无法为JAVA创建Makefile

Question

I'd like to try and create a makefile for my project. I am running this in linux not in windows, specifically ubuntu.

This is what my project directory looks like:

project_root
    /src
        A.java
        B.java
        C.java
        D.java
    /bin
       #this is where I'd like the .class files
    /include 
        A.jar
        B.jar
        C.jar
    makefile
    run.sh

And this is what my makefile looks like:

JC = javac
CLASSPATH = .:include/*
SRCPATH = ./src/
OUTDIR = ./bin/

.SUFFIXES: .java .class

.java.class:
        $(JC) -cp $(CLASSPATH) $(OUTPATH) $*.java

CLASSES = \
        $(SRCPATH)A.java \
        $(SRCPATH)B.java \
        $(SRCPATH)C.java \
        $(SRCPATH)D.java 

default: classes

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

clean:
    $(RM) $(SRCPATH)*.class

When I run make in the project directory I get this output:

make: *** No rule to make target `.java', needed by `javac'.  Stop.

Can anyone help?

Answer 1

I think you don't have a TAB character as the first character in the line when you define your .java.class suffix rule.

In make, every recipe line must include an actual TAB character (not just spaces) as the first character in the line. If the first character is not a real TAB, then it's not a recipe line.

The reason you don't get a syntax error is because your line looks like a rule, due to the colon in the CLASSPATH ; it looks like this:

javac -cp .:include/* ./bin/ .java

( $* expands to nothing here) which is parsed by make to be defining three targets, javac , -cp , and . , each of which depends on include/* , ./bin/ , and .java .

Hence your error message.