[コレクション(コンテナ)] LinkedListの基本

クエリ効率が低い、追加および削除効率が高い、安全でないスレッド、一般的にはあまり使用されない

パッケージ LinkedList をビルドする

ノード（リンクリストの作成）

public class Node {
    
    

    Node previous; //上一个节点
    Node next;     //下一个节点
    Object element;//元素数据

    public Node(Node previous, Node next, Object element) {
    
    
        this.previous = previous;
        this.next = next;
        this.element = element;
    }

    public Node(Object element){
    
    
        super();
        this.element=element;
    }

}

TestLinkedList (リンク リストをカスタマイズ、get を使用)

public class TestLinkedList {
    
    

    private Node first;
    private Node last;

    private int size;

    //[]
    //["a","b","c","d","e","f"]        2
    public Object get(int index){
    
    

        if(index<0||index>size-1){
    
    
            throw new RuntimeException("索引数字不合法："+index);
        }

        Node temp=null;

        if(index<(size>>1)){
    
        //size>>1相当于除以2，从前往后找
            temp=first;
            for(int i=0;i<index;i++){
    
    
                temp=temp.next;
            }
        }else{
    
          //从后往前找
            temp=last;
            for(int i=size-1;i>index;i--){
    
    
                temp=temp.previous;
            }
        }
        return temp.element;
    }


    public void add(Object obj){
    
    
        Node node=new Node(obj);

        if(first==null){
    
    

            first=node;
            last=node;
        }else{
    
    
            node.previous=last;
            node.next=null;

            last.next=node;
            last=node;
        }
        size++;
    }



    @Override
    public String toString() {
    
    
        //[a,b,c]  first=a  last=c
        //a,b,c
        StringBuilder sb=new StringBuilder("[");
        Node temp=first;
        while(temp!=null){
    
    
            sb.append(temp.element+",");
            temp=temp.next;
        }
        sb.setCharAt(sb.length()-1,']');
        return sb.toString();
    }

    public static void main(String[] args) {
    
    

        TestLinkedList list=new TestLinkedList();

        list.add("a");
        list.add("b");
        list.add("c");
        list.add("d");
        list.add("e");
        list.add("f");

        System.out.println(list);
        System.out.println(list.get(1)); 
    }
}

TestLinkedList02 (追加削除)

public class TestLinkedList02 {
    
    

    private Node first;
    private Node last;
    private int size;

    public void remove(int index){
    
    
        Node temp=getNode(index);

        if(temp!=null){
    
    
            Node up=temp.previous;
            Node down=temp.next;

            if(up!=null){
    
    
                up.next=down;
            }

            if(down!=null) {
    
    
                down.previous = up;
            }

            //被删除的元素是第一个元素时
            if(index==0){
    
    
                first=down;
            }

            //被删除的元素最后一个元素时
            if(index==size-1){
    
    
                last=up;
            }
            size--;
        }
    }

    public Node getNode(int index){
    
    
        Node temp=null;

        if(index<(size>>1)){
    
        //size>>1相当于除以2，从前往后找
            temp=first;
            for(int i=0;i<index;i++){
    
    
                temp=temp.next;
            }
        }else{
    
          //从后往前找
            temp=last;
            for(int i=size-1;i>index;i--){
    
    
                temp=temp.previous;
            }
        }
        return temp;
    }

    //[]
    //["a","b","c","d","e","f"]        2
    public Object get(int index){
    
    

        if(index<0||index>size-1){
    
    
            throw new RuntimeException("索引数字不合法："+index);
        }

        Node temp=getNode(index);

        return temp!=null?temp.element:null;
    }


    public void add(Object obj){
    
    
        Node node=new Node(obj);

        if(first==null){
    
    

            first=node;
            last=node;
        }else{
    
    
            node.previous=last;
            node.next=null;

            last.next=node;
            last=node;
        }
        size++;
    }



    @Override
    public String toString() {
    
    
        //[a,b,c]  first=a  last=c
        //a,b,c
        StringBuilder sb=new StringBuilder("[");
        Node temp=first;
        while(temp!=null){
    
    
            sb.append(temp.element+",");
            temp=temp.next;
        }
        sb.setCharAt(sb.length()-1,']');
        return sb.toString();
    }

    public static void main(String[] args) {
    
    

        TestLinkedList02 list=new TestLinkedList02();

        list.add("a");
        list.add("b");
        list.add("c");
        list.add("d");
        list.add("e");
        list.add("f");

        System.out.println(list);
        System.out.println(list.get(1));
        list.remove(3);
        System.out.println(list);
        list.remove(0);
        System.out.println(list);
        System.out.println(list.get(1));
        list.remove(5);
        System.out.println(list);
        System.out.println(list.get(1));

    }
}

TestLinkedList03 (ノードの挿入)

public class TestLinkedList03 {
    
    

    private Node first;
    private Node last;
    private int size;

    public void add(int index,Object obj){
    
    

        Node newNode=new Node(obj);
        Node temp=getNode(index);

        if(temp!=null){
    
    
            Node up=temp.previous;

            up.next=newNode;
            newNode.previous=up;

            newNode.next=temp;
            temp.previous=newNode;
        }
    }

    public void remove(int index){
    
    
        Node temp=getNode(index);

        if(temp!=null){
    
    
            Node up=temp.previous;
            Node down=temp.next;

            if(up!=null){
    
    
                up.next=down;
            }

            if(down!=null) {
    
    
                down.previous = up;
            }

            //被删除的元素是第一个元素时
            if(index==0){
    
    
                first=down;
            }

            //被删除的元素最后一个元素时
            if(index==size-1){
    
    
                last=up;
            }
            size--;
        }
    }

    public Node getNode(int index){
    
    
        Node temp=null;

        if(index<(size>>1)){
    
        //size>>1相当于除以2，从前往后找
            temp=first;
            for(int i=0;i<index;i++){
    
    
                temp=temp.next;
            }
        }else{
    
          //从后往前找
            temp=last;
            for(int i=size-1;i>index;i--){
    
    
                temp=temp.previous;
            }
        }
        return temp;
    }

    //[]
    //["a","b","c","d","e","f"]        2
    public Object get(int index){
    
    

        if(index<0||index>size-1){
    
    
            throw new RuntimeException("索引数字不合法："+index);
        }

        Node temp=getNode(index);

        return temp!=null?temp.element:null;
    }


    public void add(Object obj){
    
    
        Node node=new Node(obj);

        if(first==null){
    
    

            first=node;
            last=node;
        }else{
    
    
            node.previous=last;
            node.next=null;

            last.next=node;
            last=node;
        }
        size++;
    }



    @Override
    public String toString() {
    
    
        //[a,b,c]  first=a  last=c
        //a,b,c
        StringBuilder sb=new StringBuilder("[");
        Node temp=first;
        while(temp!=null){
    
    
            sb.append(temp.element+",");
            temp=temp.next;
        }
        sb.setCharAt(sb.length()-1,']');
        return sb.toString();
    }

    public static void main(String[] args) {
    
    

        TestLinkedList03 list=new TestLinkedList03();

        list.add("a");
        list.add("b");
        list.add("c");
        list.add("d");
        list.add("e");
        list.add("f");

        System.out.println(list);
        list.add(3,"若颂");
        System.out.println(list);
    }
}

TestLinkedList04 (小さなパッケージの追加、ジェネリックの追加)

public class TestLinkedList04<E> {
    
    

    private Node first;
    private Node last;
    private int size;

    public void add(int index,E element){
    
    

        checkRange(index);

        Node newNode=new Node(element);
        Node temp=getNode(index);

        if(temp!=null){
    
    
            Node up=temp.previous;

            up.next=newNode;
            newNode.previous=up;

            newNode.next=temp;
            temp.previous=newNode;
        }
    }

    public void remove(int index){
    
    

        checkRange(index);

        Node temp=getNode(index);

        if(temp!=null){
    
    
            Node up=temp.previous;
            Node down=temp.next;

            if(up!=null){
    
    
                up.next=down;
            }

            if(down!=null) {
    
    
                down.previous = up;
            }

            //被删除的元素是第一个元素时
            if(index==0){
    
    
                first=down;
            }

            //被删除的元素最后一个元素时
            if(index==size-1){
    
    
                last=up;
            }
            size--;
        }
    }

    private Node getNode(int index){
    
    

        checkRange(index);

        Node temp=null;

        if(index<(size>>1)){
    
        //size>>1相当于除以2，从前往后找
            temp=first;
            for(int i=0;i<index;i++){
    
    
                temp=temp.next;
            }
        }else{
    
          //从后往前找
            temp=last;
            for(int i=size-1;i>index;i--){
    
    
                temp=temp.previous;
            }
        }
        return temp;
    }

    //[]
    //["a","b","c","d","e","f"]        2
    public E get(int index){
    
    

        checkRange(index);

        Node temp=getNode(index);

        return temp!=null?(E)temp.element:null;
    }

    private void checkRange(int index){
    
    
        if(index<0||index>size-1){
    
    
            throw new RuntimeException("索引数字不合法："+index);
        }
    }

    public void add(E element){
    
    
        Node node=new Node(element);

        if(first==null){
    
    

            first=node;
            last=node;
        }else{
    
    
            node.previous=last;
            node.next=null;

            last.next=node;
            last=node;
        }
        size++;
    }



    @Override
    public String toString() {
    
    
        //[a,b,c]  first=a  last=c
        //a,b,c
        StringBuilder sb=new StringBuilder("[");
        Node temp=first;
        while(temp!=null){
    
    
            sb.append(temp.element+",");
            temp=temp.next;
        }
        sb.setCharAt(sb.length()-1,']');
        return sb.toString();
    }

    public static void main(String[] args) {
    
    

        TestLinkedList04<String> list=new TestLinkedList04<>();

        list.add("a");
        list.add("b");
        list.add("c");
        list.add("d");
        list.add("e");
        list.add("f");

        System.out.println(list);

        System.out.println(list.get(1));
    }
}