Dagger 2 Error: 'Cannot Be Provided...' – How to Fix Dependency Injection Issues?

Troubleshooting the Dagger 2 Dependency Provision Error: "Cannot Be Provided..."

Issue:

Dagger 2 returns the error "com.example.MyDependency cannot be provided [...]" when attempting to access a dependency. This error indicates that Dagger lacks the necessary mechanism to create or provide the specified dependency.

Explanation:

As the error message suggests, Dagger requires one of two methods to provide dependencies:

• Classes with an @Inject annotated constructor
• Methods annotated with @Provides in one of the component's modules

Fix:

To resolve this issue, ensure that you have either:

@Inject Constructor

1. Add an @Inject annotated constructor to the class that you wish to use as a dependency.

   • Example:

     class MyDependency {
         @Inject
         MyDependency() { /**/ }
     }

@Provides Method in a Module

1. Create a module and add a @Provides annotated method that returns an instance of the desired dependency.

2. Add the module to the component declaration.

   • Example:

     @Module
     class MyModule {
         @Provides
         MyDependency provideMyDependency() {
             return new MyDependency();
         }
     }
     
     @Component(modules = MyModule.class)
     interface MyComponent {
         MyDependency myDependency();
     }

Additional Notes:

• Ensure that the provided and requested dependency match exactly, including any interfaces or qualifiers.
• Consider using @Binds to map a specific implementation to an interface or superclass if you are extending or implementing other classes.

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