List introduction

️ Preface ️

This article mainly introduces Iterable、Collection、List Common method signatures and their meanings , The relationship between the three is described below .

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Iterable、Collection、List

1. The diagram

In the set framework , The relationship between the three is as follows , All three are interfaces

2.Iterable

Iterable Is a generic interface with iteration function , Indicates that the class implementing the interface can be traversed element by element .

public interface Iterable<T> {
    
    Iterator<T> iterator();
// Abstract methods in abstract classes 
    default void forEach(Consumer<? super T> action) {
    
        Objects.requireNonNull(action);
        for (T t : this) {
    
            action.accept(t);
        }
    }
    default Spliterator<T> spliterator() {
    
        return Spliterators.spliteratorUnknownSize(iterator(), 0);
    }
}

Its internal implementation is through foreach Loop or call iterator() Method to implement traversal .

3.Collection

Collection It is inherited from Iterable The generic interface of , The interface used to implement the collection .

public interface Collection<E> extends Iterable<E>{
    };

Common method signature ：

Method	effect
add(Object o)	Add an element to the collection
addAll(Collection c)	Add a collection to a collection c All elements of
clear（）	Remove all elements
contains(Object o)	Determine whether the collection contains the element
containsAll（collection c）	Determine whether a set contains a set c The elements of
isEmpty（）	Determines if the set is empty
iteration（）	return iteration object , Used to traverse all elements in the collection
remove（Object o）	Delete a specified element
removeAll（collection c）	Delete the collection c All elements in
retainAll（Collection c）	Keep collections only c The elements that appear in
int size（）	Returns the number of elements in the collection
Object[] toArray()	Convert a set into an array

4.List

List It's a linear table , namely n A finite sequence of elements of the same type , On this sequence, operations such as adding, deleting, modifying and querying variables can be performed .

Be careful ：
List It's an interface , It cannot be directly used to instantiate .
If you want to use , Must instantiate List Implementation class of . In the set framework ,ArrayList and LinkedList It's all done List Interface .

Common method tag names ：

Method	effect
boolean add(E e)	Tail insertion e
void add(int index, E element)	take e Insert into index Location
boolean addAll(Collection<? extends E> c)	Tail insertion c The elements in
E remove(int index)	Delete index Location elements
boolean remove(Object o)	Delete the first o
E get(int index)	Get subscript index Location elements
E set(int index, E element)	Subscript index The location element is set to element
void clear()	Empty
boolean contains(Object o)	Judge o Is it in the linear table
int indexOf(Object o)	Return to the first o The subscript
int lastIndexOf(Object o)	Go back to the last o The subscript
List subList(int fromIndex, int toIndex)	Interception part list

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️ Last words ️

Summing up difficulties , hope uu Don't be stingy with your (＾Ｕ＾)ノ~ＹＯ！！ If there is a problem , Welcome comments and corrections in the comment area