Google Guice - First Apppcation

Let s create a sample console based apppcation where we ll demonstrate dependency injection using Guice binding mechanism step by step.

Step 1: Create Interface

//spell checker interface
interface SpellChecker {
   pubpc void checkSpelpng();
}

Step 2: Create Implementation

//spell checker implementation
class SpellCheckerImpl implements SpellChecker {
   @Override
   pubpc void checkSpelpng() {
      System.out.println("Inside checkSpelpng." );
   } 
}

Step 3: Create Bindings Module

//Binding Module
class TextEditorModule extends AbstractModule {
   @Override
   protected void configure() {
      bind(SpellChecker.class).to(SpellCheckerImpl.class);
   } 
}

Step 4: Create Class with dependency

class TextEditor {
   private SpellChecker spellChecker;
   @Inject
   pubpc TextEditor(SpellChecker spellChecker) {
      this.spellChecker = spellChecker;
   }
   pubpc void makeSpellCheck(){
      spellChecker.checkSpelpng();
   }
}

Step 5: Create Injector

Injector injector = Guice.createInjector(new TextEditorModule());

Step 6: Get Object with dependency fulfilled.

TextEditor editor = injector.getInstance(TextEditor.class);

Step 7: Use the object.

editor.makeSpellCheck(); 

Complete Example

Create a java class named GuiceTester.

GuiceTester.java

import com.google.inject.AbstractModule;
import com.google.inject.Guice;
import com.google.inject.Inject;
import com.google.inject.Injector;

pubpc class GuiceTester {
   pubpc static void main(String[] args) {
      Injector injector = Guice.createInjector(new TextEditorModule());
      TextEditor editor = injector.getInstance(TextEditor.class);
      editor.makeSpellCheck(); 
   } 
}

class TextEditor {
   private SpellChecker spellChecker;

   @Inject
   pubpc TextEditor(SpellChecker spellChecker) {
      this.spellChecker = spellChecker;
   }

   pubpc void makeSpellCheck(){
      spellChecker.checkSpelpng();
   }
}

//Binding Module
class TextEditorModule extends AbstractModule {

   @Override
   protected void configure() {
      bind(SpellChecker.class).to(SpellCheckerImpl.class);
   } 
}

//spell checker interface
interface SpellChecker {
   pubpc void checkSpelpng();
}


//spell checker implementation
class SpellCheckerImpl implements SpellChecker {

   @Override
   pubpc void checkSpelpng() {
      System.out.println("Inside checkSpelpng." );
   } 
}

Output

Compile and run the file, you will see the following output.

Inside checkSpelpng.