Answers for "java to byte code"

convert string to byte java

String example = "Convert Java String";
  byte[] bytes = example.getBytes();

what is bytecode in java

When a javac compiler compiler compiles a class it generates .class file. 
This .class file contains set of
instructions called byte code. Byte code is a machine independent language 
and contains set of
instructions which are to be executed only by JVM. JVM can understand 
this byte codes.