learning_java_generics.md

path	title
/learnings/java_generics	Learnings: Java: Generics

Table Of Contents

• Generic Declarations >
  • Only an instance method, not on a class
  • T must inherit from some base class
  • T must implement some interface
• And Type Erasure >
• Book Recommendations

Generic Declarations <Learning_Java_Generic_Declarations>>

Only an instance method, not on a class

class Thing {
    public <T> void methodName( String thing, T whatsit ) {

    }
}

T must inherit from some base class

public <T extends String> void fooBar(T) { ... }

T must implement some interface

public <T extends String & Runnable> void foobar(T) { ... }

The & signals that the class must implement that thing.

If you want to just check for interface implementation can do extends Object & Runnable.

And Type Erasure <<Java_Type_Erasure>>

See also:

• <<Kotlin_Type_Erasure>>

Book Recommendations

• Java Generics