Java 中模仿源码自定义ArrayList
最近看了下ArrayList的源码，抽空根据ArrayList的底层结构写了一个功能简单无泛型的自定义ArrayLsit，帮助自己更好理解ArrayList:，其实现的底层数据结构为数Object组，代码如下：
public class MyArrayList {
private Object[] elementData;
private int size;
public int size(){
return size;
}
public boolean isEmpty(){
return size==0;
}
//默认容量为10
public MyArrayList(){
this(10);
}
public MyArrayList(int initialCapacity){
if(initialCapacity<0){
try {
throw new Exception();
} catch (Exception e) {
e.printStackTrace();
}
}
elementData = new Object[initialCapacity];
}
public void add(Object obj){
//数组扩容和数据的拷贝，重新new一个数组
if(size==elementData.length){
Object[] newArray = new Object[size*2+1];
System.arraycopy(elementData, 0, newArray, 0, elementData.length);
elementData = newArray;
}
elementData[size++]=obj;
// size++;
}
public Object get(int index){
rangeCheck(index);
return elementData[index];
}
public void remove(int index){
rangeCheck(index);
int numMoved = size - index - 1;
if (numMoved > 0){
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
}
elementData[--size] = null; // Let gc do its work
}
public void remove(Object obj){
for(int i=0;i=size){
try {
throw new Exception();
} catch (Exception e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
MyArrayList list = new MyArrayList(3);
list.add("333");
list.add("444");
list.add("5");
list.add("344433");
list.add("333");
list.add("333");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
System.out.println("------------------------------");
list.remove("444");
list.add(2, "a");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
}
测试结果：
333 444 5 344433 333 333 ------------------------------ 333 5 a 344433 333 333
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