package cn.pmcse.myCollection;
public class ArrayList { private Object[] value; private int count;//计数器 0 ArrayList(){ // value=new Object[16]; this(16);//this 必须首行 } ArrayList(int objsize) { value=new Object[objsize];//******************第二步 Object[] value=new Object[1] } public void copy(Object[] ar) { if(value.length<ar.length) { int newLength=ar.length*2; Object[] t2=new Object[newLength]; value=t2; } for(int i=0;i<ar.length;i++) { value[i]=ar[i]; } } public void add(Object obj) { value[count]=obj; System.out.println("********************"+count);//*************************** 0 count++; System.out.println("********************"+count);//*************************** 1 if(count>=value.length) { int newSize=value.length*2;// Object[] newList=new Object[newSize]; for(int i=0;i<value.length;i++) { newList[i]=value[i]; } value=newList; } } public Object get(int index) { if(index<0||index>value.length-1) {//0-（length-1） try { throw new Exception();//手动抛出异常。 }catch(Exception e) { e.printStackTrace(); } } return value[index];//返回value索引index的对象 } public void set(int index,Object obj) { if(index<0||index>value.length-1) {//0-（length-1） try { throw new Exception();//手动抛出异常。 }catch(Exception e) { e.printStackTrace(); } } value[index]=obj; } public int size() { return count;//返回数量 } public int indexOf(Object obj) { if(obj==null) { return -1; }else { for(int i=0;i<value.length;i++) { if(obj==value[i]) { return 1; } } return -1; } } public int lastIndexOf(Object obj) { if(obj==null) { return -1; }else { for(int i=value.length-1;i>=0;i--) { if(obj==value[i]) { return 1; } } return -1; } } public String toString() { return "默认调用这个玩意儿toString()"; } public static void main(String[] args) { ArrayList list=new ArrayList(1); //******************第一步 size=1 list.add(new Human("阿莫西林")); Human h=(Human)list.value[0]; h.setName("胶囊"); list.add("测试"); ArrayList list2=new ArrayList(1); System.out.println(h.getName());//胶囊 System.out.println(list.get(1));//测试 System.out.println(list.count);//2 System.out.println(list.size());//2 System.out.println(list.value.length);//4 System.out.println(list.indexOf(h)); System.out.println(list.lastIndexOf(h)); System.out.println(list.value[3]); list2.copy(list.value); Human h2= (Human)list2.value[0]; list2.set(0, "对不对"); System.out.println(list2.value[0]); System.out.println(list2.value.length); System.out.println(list2.count); System.out.println(h2.getName()); ArrayList ss =new ArrayList(); System.out.println(ss); // for(int i=0;i<16;i++) { // list.add(i); // } // System.out.println(list.value.length); // System.out.println(list.value[31]); } }
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import java.util.ArrayList; public class MyArrayList { private Object value[]; private int size; public MyArrayList() { // value = new Object[16]; this(2); } public MyArrayList(int size) { value = new Object[size]; } public void add(Object obj) { value[size] = obj; size++; if (size >= value.length) { // 装不下了，将要扩展容量了 int newCapacity = value.length * 2; Object[] newList = new Object[newCapacity]; // System.arraycopy(src, srcPos, dest, destPos, length); for (int i = 0; i < value.length; i++) { newList[i] = value[i]; } value = newList; } } public int size() { return size; } public boolean isEmpty() { return size == 0; } public int indexOf(Object obj) { if (obj == null) { return -1; } else { for (int i = 0; i < value.length; i++) { if (obj == value[i]) { return i; } } return -1; } } public int lastIndexOf(Object obj) { if (obj == null) { return -1; } else { for (int i = value.length - 1; i >= 0; i--) { if (obj == value[i]) { return i; } } return -1;// return 作用：1，返回出去值，2，结束语句。 } } public void rangleCheck(int index) { if (index < 0 || index > size - 1) {// [0,size-1] try { throw new Exception(); } catch (Exception e) { e.printStackTrace(); } } } public Object set(int index, Object object) { rangleCheck(index); Object old = value[index]; value[index] = object; return old; } public Object get(int index) { rangleCheck(index); return value[index]; } public static void main(String[] args) { MyArrayList list = new MyArrayList(); list.add("aaa"); list.add(new Human("高淇")); list.add("bbb"); list.add("bbb"); list.add("bbb"); list.add("bbb"); Human h = (Human) list.get(1); System.out.println(h.getName()); System.out.println("*********************"); System.out.println(list.get(0)); System.out.println(list.get(1)); System.out.println(list.get(2)); System.out.println("*******************"); System.out.println(list.size); } } class Human { private String name; public Human(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } }
