- Google Guice Tutorial
- Guice - Home
- Guice - Overview
- Guice - Environment Setup
- Guice - First Application
- Bindings Examples
- Guice - Linked binding
- Guice - Binding Annotations
- Guice - @Named binding
- Guice - Constant Bindings
- Guice - @Provides Annotation
- Guice - Provider Class
- Guice - Constructor Bindings
- Guice - Inbuilt Bindings
- Guice - Just-in-time Bindings
- Injection Examples
- Guice - Constructor Injection
- Guice - Method Injection
- Guice - Field Injection
- Guice - Optional Injection
- Guice - On-demand Injection
- Miscellaneous Examples
- Guice - Scopes
- Guice - AOP
- Guice Useful Resources
- Guice - Quick Guide
- Guice - Useful Resources
- Guice - Discussion
Google Guice - Linked Bindings
In Linked bindings, Guice maps a type to its implementation. In below example, we've mapped SpellChecker interface with its implementation SpellCheckerImpl.
bind(SpellChecker.class).to(SpellCheckerImpl.class);
We can also mapped the concrete class to its subclass. See the example below:
bind(SpellCheckerImpl.class).to(WinWordSpellCheckerImpl.class);
Here we've chained the bindings. Let's see the result in complete example.
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; public class GuiceTester { public 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 public TextEditor(SpellChecker spellChecker) { this.spellChecker = spellChecker; } public void makeSpellCheck(){ spellChecker.checkSpelling(); } } //Binding Module class TextEditorModule extends AbstractModule { @Override protected void configure() { bind(SpellChecker.class).to(SpellCheckerImpl.class); bind(SpellCheckerImpl.class).to(WinWordSpellCheckerImpl.class); } } //spell checker interface interface SpellChecker { public void checkSpelling(); } //spell checker implementation class SpellCheckerImpl implements SpellChecker { @Override public void checkSpelling() { System.out.println("Inside checkSpelling." ); } } //subclass of SpellCheckerImpl class WinWordSpellCheckerImpl extends SpellCheckerImpl{ @Override public void checkSpelling() { System.out.println("Inside WinWordSpellCheckerImpl.checkSpelling." ); } }
Output
Compile and run the file, you will see the following output.
Inside WinWordSpellCheckerImpl.checkSpelling.
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