Introduction (editing)

About the basics of generics

Example)

List<String> list = new ArrayList<>();
list.add("aaa");
list.add(1); //Compile error

-[x] You can specify the type to be included in List

• [x]

Prohibiting new type variable E in generic typeclass

class Owner<E>{
  E createObject(){
    return new E();
  }
}

Compile error

-[] Task 1 -[x] Task 2

Qiita

type parameter The variable part inside

<>.

Type variable

Variables qualified as type parameters

type argument

The specific type to pass to <> when using a generic type. String part of List

Parameterized type

type A type that can actually be used by passing an argument. List itself

When you declare List

class List<String> {
	private String element;
	String get() {
		return element;
	}
	void put(String e) {
		this.element = e;
	}
}

Is created internally. (Unsettled)