java手写ArrayList
原创
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public class MyArrayList<Integer> {
private final int SIZE=10;
private int size=0;
public Integer arr[];
public MyArrayList(){
arr=(Integer[])new Object[SIZE];
}
public void add(Integer a,int index){
if(index>arr.length){
arr=java.util.Arrays.copyOf(arr, 10+arr.length);
size++;
}else if(index<0){
try {
throw new Exception();
} catch (Exception e) {
e.printStackTrace();
}
}else{
arr[index]=a;
size++;
}
}
public void add(Integer a){
if(size==arr.length){
arr[size]=a;
size++;
}else{
arr[size]=a;
size++;
}
}
public boolean remove(int index){
if(index<0||index>size){
try {
throw new Exception();
} catch (Exception e) {
e.printStackTrace();
return false;
}
}else{
for(int i=index;i<arr.length-1;i++){
arr[i]=arr[i+1];
}size--;
return true;
}
}
public void clear(){
arr=(Integer[])new Object[SIZE];
size=0;
}
public void set(Integer a,int index){
if(index>size){
try {
throw new Exception();
} catch (Exception e) {
e.printStackTrace();
}
}else if(index==size){
arr[index]=a;
size++;
}
else if(index<size){
arr[index]=a;
}
}
public void get(int index){
if(index<0||index>size){
try {
throw new Exception();
} catch (Exception e) {
e.printStackTrace();
}
}else{
System.out.println(arr[index]);
}
}
public boolean isEmpty(){
return size==0;
}
public java.util.Iterator<Integer>iterator(){
return new ArrayListIterator();
}
public class ArrayListIterator implements java.util.Iterator<Integer>{
private int current=0;
@Override
public boolean hasNext() {
return size>current;
}
@Override
public Integer next() {
if(!hasNext()){
return null;
}else{
return arr[current++];}
}
@Override
public void remove() {
// TODO Auto-generated method stub
MyArrayList.this.remove(--current);
}
}
}
