MyFolder/makefile
MyFolder/sample.java
MyFolder/subdir/abc$1.class
MyFolder/subdir/test.java
MyFolder/xyz.class

hexdump subdir/abc$1.class xyz.class

default:
    hexdump $(shell find -name '*.class')

hexdump ./subdir/abc$1.class ./xyz.class
hexdump: ./subdir/abc.class: No such file or directory
make: *** [makefile:3: default] Error 1

default:
    hexdump subdir/abc$$1.class xyz.class