public class ArrayList {
/*通过数组模拟ArrayList结构，完成容器的创建、添加、修改、删除，以及可以
遍历自定义的结构，提示可以ArrayList源码。
*/
int n=2;
int size=-1;
Object []array;
public ArrayList(){
array=new Object[n];
}
public static void main(String[] args) {
ArrayList arrayList=new ArrayList();
arrayList.add("f");
arrayList.add("a");
arrayList.add("w");
for (int i = 0; i <arrayList.size+1 ; i++) {
System.out.println(arrayList.getarray(i));
}
System.out.println("------------");
arrayList.add(2, "2");
// 越界，报错
arrayList.add(5, "5");
for (int i = 0; i <arrayList.size ; i++) {
System.out.println(arrayList.getarray(i));
}
System.out.println("--------------");
arrayList.remove(2);
arrayList.remove("f");
for (int i = 0; i <arrayList.size ; i++) {
System.out.println(arrayList.getarray(i));
}
arrayList.set(1, "10");
System.out.println("--------------");
for (int i = 0; i <arrayList.size ; i++) {
System.out.println(arrayList.getarray(i));
}
}
public void enlarge(){
n=n*2+1;
Object [] newarray=new Object[n];
System.arraycopy(array, 0, newarray, 0, array.length);
array=newarray;
}
public Object getarray(int i){
return array[i];
}
public int add(int index,Object obj){
if(index>n-1){
enlarge();
}
if(index>size&&index<n){
System.out.println("java.lang.IndexOutOfBoundsException");
}
for (int i=index; i <=size; i++) {
array[index+1]=array[index];
}
array[index]=obj;
size++;
return size;
}
public int add(Object obj){
if(size>=n-1){
enlarge();
}
array[size+1]=obj;
size++;
return size;
}
public void remove(int index){
for (int i = index; i<size; i++) {
array[i]=array[i+1];
}
array[size]=null;
size--;
}
public void remove(Object obj){
for (int i = 0; i <=size ; i++) {
if(obj.equals(getarray(i))==true){
remove(i);
}
}
}
public void set(int index,Object obj){
array[index]=obj;
}
