dotGo 2014

.gitignore

*.class

ExplicitStringer.java

class ExplicitStringer implements Stringer {
	public String String() {
		return "I am a real Stringer!";
	}
}

java compiler error.txt

Main.java:11: error: method print in class Main cannot be applied to given types;
		Main.print(notStringer);
		    ^
  required: Stringer
  found: NotExplicitStringer
  reason: actual argument NotExplicitStringer cannot be converted to Stringer by method invocation conversion
1 error

main.go

package main 

import (
	"fmt"
)

type ImplicitStringer struct {
	value string
}

func (s ImplicitStringer) String() string {
	return s.value
}

func Print(stringer fmt.Stringer) {
	fmt.Println(stringer)
}

func main() {
	s := ImplicitStringer{
		value: "42",
	}

	Print(s)
}

Main.java

public class Main {
	public static void main(String [] args) {
		// Works because ExplicitStringer 
		// explictly implements Stringer interface
		ExplicitStringer stringer = new ExplicitStringer();
		Main.print(stringer);

		// Does not compile because NotExplicitStringer does not
		// explictly implements Stringer interface
		NotExplicitStringer notStringer = new NotExplicitStringer();
		Main.print(notStringer);
	}

	public static void print(Stringer stringer) {
		System.out.println(stringer.String());
	}
}

NotExplicitStringer.java

class NotExplicitStringer {
	public String String() {
		return "I am concrete!";
	}
}

Stringer.go

type Stringer interface {
	String() string
}

Stringer.java

public interface Stringer{  
	string String()
}