JAVA仿写ArrayList

落日映苍穹つ 2023-03-03 08:44 52阅读 0赞

# 功能 #

1.  Object get(int index); 获取该位置数据
2.  boolean add(Object obj); 添加数据
3.  void set(int index, Object obj); 替换该位置数据
4.  boolean remove(int index); 清除该位置数据
5.  boolean isEmpty(); list是否为空
6.  boolean isFull(); list是否已满
7.  int size(); 返回当前list大小
8.  void clear(); 清除list中所有数据
9.  void show()；遍历显示list内容
10. void extend()； list扩容

# 代码： #

//接口
    
    package copyList;
    
    public interface List {
    
        Object get(int index);
    
        boolean add(Object obj);
    
        void set(int index, Object obj);
    
        boolean remove(int index);
    
        boolean isEmpty();
        
        boolean isFull();
        
        int size();
        
        void clear();
        
    }

//实现
    package copyList;
    
    import java.util.Arrays;
    
    public class MyArrayList implements List {
    
    	// 数组默认大小
    	private static int Length = 0;
    	// 数组下标
    	private static int tag = 0;
    	// 核心数组
    	private static Object[] obj;
    
    
    	public void show() {
    		if (obj==null) {
    			System.out.println("当前ArrayList空");
    		}else {
    			for (Object object : obj) {
    				if (object==null) {
    					continue;
    				}else {
    					System.out.print(object + " ");
    				}
    			}
    			System.out.println();
    		}
    		
    	}
    
    	@Override
    	public Object get(int index) {
    		if (obj[index]==null) {
    			System.out.print("当前位置没有数据，返回 ");
    		}
    		return obj[index];
    	}
    	
    	@Override
    	public boolean add(Object object) {
    		if (isFull()||isEmpty()) {
    			extend();
    		}
    		obj[tag] = object;
    		tag++;
    		return false;
    	}
    	
    	private void extend() {
    		if (Length==0) {
    			obj = new Object[10];
    			Length = 10;
    		}else if (isFull()) {
    			Length = (Length>>1)+Length;
    			obj = Arrays.copyOf(obj, Length);
    		}
    	}
    
    	@Override
    	public void set(int index, Object obj) {
    		this.obj[index] = obj;
    	}
    
    	@Override
    	public boolean remove(int index) {
    		for (int i = index; i < tag; i++) {
    			obj[index] = obj[index+1];
    			index++;
    		}
    		tag--;
    		return true;
    	}
    
    	@Override
    	public boolean isEmpty() {
    		return obj==null ? true:false;
    	}
    	
    	@Override
    	public boolean isFull() {
    		return tag==Length ? true:false;
    	}
    
    	@Override
    	public int size() {
    		return tag;
    	}
    
    	@Override
    	public void clear() {
    		obj = null;
    		Length = 0;
    		tag = 0;
    	}
    
    	
    
    }

# 示例： #

![20200730170448607.png][]

![20200730170500743.png][]

[20200730170448607.png]: /images/20230208/fad0fc4331414f5eb58ac461159a89a8.png
[20200730170500743.png]: /images/20230208/a3279d589be244d2b8a1c961ec049927.png