add 2-1-JavaBasic examples

java/2-1-JavaBasic/Animals1.java

java/2-1-JavaBasic/Animals2.java

java/2-1-JavaBasic/Bicycle.java

java/2-1-JavaBasic/Bikes1.java

java/2-1-JavaBasic/Bikes2.java

java/2-1-JavaBasic/Hello.java

java/2-1-JavaBasic/makefile