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Array.java
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164 lines (145 loc) · 3.92 KB
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package code_00_array;
/**
* 二次封装属于我们自己的数组
*/
public class Array<E> {
private E[] data;
private int size;
public Array(int capacity){
data=(E[])new Object[capacity];
size=0;
}
//无参构造函数，默认数组的容量是10
public Array(){
this(10);
}
public int getSize(){
return size;
}
public int getCapacity(){
return data.length;
}
public boolean isEmpty(){
return size==0;
}
//在所有元素后添加新元素
public void addLast(E e) {
//要先判断是否有空间来容纳新元素
/*if(size==data.length){
throw new IllegalArgumentException("AddLast failed,array is full");
}
data[size]=e;
size++;*/
add(size,e);
}
//在所有元素前添加新元素
public void addFirst(E e){
add(0,e);
}
//在index位置插入元素
public void add(int index,E e){
/* if(size==data.length){
throw new IllegalArgumentException("Add failed,array is full");
}*/
if(size==data.length){
resize(data.length*2);
}
if(index<0 || index>size){
throw new IllegalArgumentException("Add Failed,0<=index<=size is required");
}
//index位置后的元素向右移动
for(int i=size;i>index;i--){
data[i]=data[i-1];
}
data[index]=e;
size++;
}
//获取index位置的元素
public E get(int index){
if(index<0 || index>=size){
throw new IllegalArgumentException("Get failed,index is illegal");
}
return data[index];
}
//设置index位置元素值为e
public void set(int index,E e){
if(index<0 || index>=size){
throw new IllegalArgumentException("Get failed,index is illegal");
}
data[index]=e;
}
//查找数组中是否有元素e,有就返回下标，没有就返回-1
public boolean contains(E e){
for(int i=0;i<size;i++){
if(data[i]==e){
return true;
}
}
return false;
}
//查找数组中元素e所在索引
public int find(E e){
for(int i=0;i<size;i++){
if(data[i]==e){
return i;
}
}
return -1;
}
//删除指定位置元素
public E remove(int index){
/*if(size==0){
throw new IllegalArgumentException("Remove failed,array is empty");
}*/
/* if(size==data.length/2){
resize(data.length/2);
}*/
if(size==data.length/4 && data.length/2!=0){
resize(data.length/2);
}
if(index<0 || index>=size){
throw new IllegalArgumentException("Remove failed,index is illegal");
}
E ret=data[index];
for(int i=index+1;i<size;i++){
data[i-1]=data[i];
}
size--;
data[size]=null;//loitering objects
return ret;
}
public E removeFirst(){
return remove(0);
}
public E removeLast(){
return remove(size-1);
}
public void removeElement(E e){
int index=find(e);
if(index!=-1){
remove(index);
}
}
//调整数组大小
private void resize(int newCapacity){
E[] newData=(E[])new Object[newCapacity];
for(int i=0;i<size;i++){
newData[i]=data[i];
}
data=newData;
}
@Override
public String toString(){
StringBuilder builder=new StringBuilder();
builder.append(String.format("Array size=%d,capacity=%d\n",size,data.length));
builder.append("[");
for(int i=0;i<size;i++){
builder.append(data[i]);
if(i!=size-1){
builder.append(", ");
}
}
builder.append("]");
return builder.toString();
}
}