java - Guice does not load Bindings -

interface -

public interface add {     public int add(int a, int b) } 

implementation 1 -

class martianadd implements add  public int add(int a, int b) {     return -a+b; } } 

implementation 2-

public class simpleadd implements add { public simpleadd() {} public int add(int a, int b) {     return + b } }   class bindings extends abstractmodule { protected void configure() {     bind(add).annotatedwith(names.named('earth')).to(simpleadd)     bind(add).annotatedwith(names.named('mars')).to(martianadd) } } 

main class -

class test { public static void main(string[] args) {     injector injector = guice.createinjector(new bindings())     @named('mars') add = injector.getinstance(add)     print a.class     print a.add(5, 8) } } 

exception -

exception in thread "main" com.google.inject.configurationexception: guice configuration errors:  1) no implementation in.ksharma.add bound.   while locating in.ksharma.add 

why doesn't guice load bindings?

this problem, believe:

@named('mars') add = injector.getinstance(add) 

you're asking instance of add - fact variable you're assigning result has @named annotation irrelevant guice. believe you'll need use injector.getinstance(key) key right class with right name binding, e.g.

add add = injector.getinstance(key.get(add, names.named('mars')))