title: Makefile: $(shell find ...) doesn't output correct results
body: <pre><code>ALL_SRC := $(shell find . -name "*.java")
  ALL_CLASS = $(shell find . -name "*.class")
  
  all:
      @echo "Compiling..."
      $(JAVAC) $(ALL_SRC)
      echo $(ALL_CLASS)
      find . -name "*.class"
  </code></pre>
  
  <p>When the class files exist at the time of running this makefile, <code>$(ALL_CLASS)</code> is correctly set. </p>
  
  <p>How come <code>echo $(ALL_CLASS)</code> prints a blank while <code>find . -name "*.class"</code> returns all class files within the directory?</p>