手写实现List接口的ArrayList类

Posted 2022-05-24 fangtingfei

 

接口  MyLlist.java

 1 package cn.ftf.myarraylist;
 2 
 3 public interface MyList 
 4     public void clear();
 5     public boolean isEmpty();
 6     public int length();
 7     public Object get(int i) throws Exception;
 8     public void add(Object obj);
 9     public void inset(int i,Object obj) throws Exception;
10     public void remove(int i) throws Exception;
11     public int indexOf(Object obj);
12     public void display();
13 

 集合类  MyArrayList.java

 1 package cn.ftf.myarraylist;
 2 
 3 public class MyArrayList implements MyList
 4     private Object[] obj;
 5     private int a=3;
 6     private int curLen=0;
 7     
 8 
 9     public MyArrayList() 
10         super();
11         obj=new Object[a];
12     
13 
14     @Override
15     public void clear() 
16         curLen=0;
17     
18 
19     @Override
20     public boolean isEmpty() 
21         return curLen==0;
22     
23 
24     @Override
25     public int length() 
26         return curLen;
27     
28 
29     @Override
30     public Object get(int i) throws Exception
31         if(i<0||i>curLen-1) 
32             throw new Exception("第"+i+"个元素不存在！");
33         
34         return obj[i];
35     
36 
37     @Override
38     public void add(Object obj) 
39         if(curLen==a) 
40             a=a*2;
41             Object [] b=this.obj;
42             this.obj=new Object[a];
43             for(int i=0;i<=curLen-1;i++) 
44                 this.obj[i]=b[i];
45             
46         
47         this.obj[curLen]=obj;
48         curLen++;
49     
50     @Override
51     public void inset(int i, Object obj) throws Exception
52         if(i<0||i>curLen) 
53             throw new Exception("插入位置非法！");
54         
55         if(curLen==a) 
56             a=a*2;
57             Object [] b=this.obj;
58             this.obj=new Object[a];
59             for(int i1=0;i1<=curLen-1;i1++) 
60                 this.obj[i1]=b[i1];
61             
62         
63         for(int ii=curLen-1;ii>=i;ii--) 
64             this.obj[ii+1]=this.obj[ii];
65         
66         this.obj[i]=obj;
67         curLen++;
68     
69 
70     @Override
71     public void remove(int i) throws Exception 
72         if(i<0||i>curLen) 
73             throw new Exception("移除位置非法！");
74         
75         for(int ii=i+1;ii<=curLen;ii++) 
76             obj[ii]=obj[ii-1];
77         
78         curLen--;
79     
80 
81     @Override
82     public int indexOf(Object obj) 
83         for(int i=0;i<=curLen;i++) 
84             if(this.obj[i].equals(obj)) 
85                 return i;
86             
87         
88         return -1;
89     
90 
91     @Override
92     public void display() 
93         for(int i=1;i<=curLen;i++) 
94             System.out.println(obj[i-1]+"  ");
95         
96         
97     
98 
99 

测试类  Test01.java

 1 package cn.ftf.myarraylist;
 2 
 3 public class Test01 
 4     public static void main(String[] args) throws Exception 
 5         MyArrayList ma=new MyArrayList();
 6         MyList ml=new MyArrayList();
 7         ml.add(1);
 8         ml.add("hello");
 9         ml.add(2);
10         ml.add("word");
11         ml.display();
12         
13         System.out.println(ml.get(3));
14         ml.inset(3, "插入的");
15         ml.inset(3, "插入的2");
16         ml.display();
17         System.out.println(ml.length());
18         System.out.println(ml.isEmpty());
19         ml.clear();
20         System.out.println(ml.isEmpty());
21 
22 
23     
24 
25 
/*
运行结果：（无差错）
1  
hello  
2  
word  
word
1  
hello  
2  
插入的2  
插入的  
word  
6
false
true
*/