问为什么我的makefile不能编译java接口？

EN

javac src/hw4/ClosedState.java
src/hw4/ClosedState.java:3: error: cannot find symbol
public class ClosedState implements State {
                                    ^
  symbol: class State
src/hw4/ClosedState.java:6: error: cannot find symbol
    public void doAction(Context context) { context.setState(this); }
                         ^
  symbol:   class Context
  location: class ClosedState
src/hw4/ClosedState.java:5: error: method does not override or implement a method from a supertype
    @Override
    ^
3 errors

JAVAC=javac
sources = $(shell find ./src/hw4/ -type f -name '*.java')
classes = $(sources:.java=.class)

all: myProgram jar clean

myProgram: $(classes)

clean :
        rm -f *.class

%.class : %.java
        $(JAVAC) $<

jar: $(classes)
        jar cvf dl.jar $(classes)