爪哇国新游记之十六----泛型单链表类

/**
 * 单链表节点类
 * @param <T>
 */
class Node<T extends Object>{
    protected T value;
    protected Node next;
}

/** 
 * 单链表类
 * @param <T>
 */
public class ChainList<T extends Object>{
    private Node<T> first;
    
    public void addTail(T t){
        Node<T> newNode=new Node<T>();
        newNode.value=t;
        
        if(first==null){                        
            first=newNode;
        }
        else{
            Node<T> curr=first;
            
            while(curr.next!=null){
                curr=curr.next;
            }
            
            curr.next=newNode;
        }
    }
    
    public void addHead(T t){
        Node<T> newNode=new Node<T>();
        newNode.value=t;
        newNode.next=first;
        first=newNode;
    }
    
    public int size(){
        int size=0;
        Node<T> curr=first;
        
        while(curr!=null){
            size++;
            curr=curr.next;
        }
        
        return size;
    }
    
    public T get(int index){
        if(index<0){
            throw new IllegalArgumentException("下标不能是负数");
        }
        else{
            Node<T> curr=first;
            
            while(curr!=null){                
                if(index==0){
                    return curr.value;
                }
                
                index--;
                curr=curr.next;
            }
            
            throw new NullPointerException();
        }
    }
    
    public void remove(int index){
        if(index<0){
            throw new IllegalArgumentException("下标不能是负数");
        }
        else{
            
            if(index==0){
                Node<T> next=first.next;                
                first=next;
            }
            else{            
                Node<T> curr=first;
                Node<T> prev=curr;
                
                while(curr!=null){                
                    if(index==0){
                        prev.next=curr.next;
                        return;
                    }
                    
                    index--;
                    prev=curr;
                    curr=curr.next;
                }
                
                throw new NullPointerException();
            }
        }
    }
    
    public void display(){
        System.out.print("链表元素有");
        Node<T> curr=first;
        
        while(curr!=null){
            System.out.print(curr.value+",");
            curr=curr.next;
        }
        System.out.println();
    }
    
    public static void main(String[] args){
        ChainList<String> ls=new ChainList<String>();
        
        ls.addTail("A");
        ls.addTail("B");
        ls.addTail("C");
        ls.display();
        
        ls.addHead("1");
        ls.display();
        System.out.println("数组长度为:"+ls.size());
        System.out.println("第三个元素为:"+ls.get(2));
        
        for(int i=0;i<ls.size();i++){
            System.out.println("第"+(i+1)+"个元素为:"+ls.get(i));
        }
        
        ls.addTail("E");
        ls.addTail("F");
        ls.remove(0);        
        ls.display();
        
        ls.remove(1);        
        ls.display();
        
        ls.remove(ls.size()-1);        
        ls.display();
        
        for(int i=0;i<ls.size();i++){
            System.out.println("第"+(i+1)+"个元素为:"+ls.get(i));
        }
    }
}

输出：

链表元素有A,B,C,
链表元素有1,A,B,C,
数组长度为:4
第三个元素为:B
第1个元素为:1
第2个元素为:A
第3个元素为:B
第4个元素为:C
链表元素有A,B,C,E,F,
链表元素有A,C,E,F,
链表元素有A,C,E,
第1个元素为:A
第2个元素为:C
第3个元素为:E