java——数组栈ArrayStack

栈的应用：

　　undo操作-编辑器

　　系统调用栈-操作系统

　　括号匹配-编译器

以下是动态数组实现的数组栈：

定义动态数组：

package Date_pacage;
public class Array {
//叫它静态数组
//private int[] data;
private E[] data;
private int size;
//构造函数
public Array(int capacity) {
data = (E[])new Object[capacity];
size = 0;
}
//无参数的构造函数，默认数组的容量为10
public Array() {
this(10);
}
public int getSize() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
public int getCapacity() {
return data.length;
}
// O(1)
public void addLast(E e) {
add(size, e);
}
// O(n)
public void addFirst(E e) {
add(0, e);
}
// O(n/2) = O(n)
public void add(int index, E e) {
if(size>=data.length)
resize(2 *data.length);
if(index<0 || index>size)
throw new IllegalArgumentException("Add failed.index is error.");
for(int i=size-1;i>=index;i--) {
data[i+1] = data[i];
}
data[index] = e;
size++;
}
@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append(String.format("Array: size = %d, capacity = %d\n", size, data.length));
res.append("[");
for(int i = 0 ; i) {
res.append(data[i]);
if(i != size - 1)
res.append(", ");
}
res.append("]");
return res.toString();
}
public E get(int index) {
if(index <0 || index >= size)
throw new IllegalArgumentException("Get failed. Index is illegal");
return data[index];
}
public E getFirst() {
return get(size - 1);
}
public E getLast() {
return get(0);
}
void set(int index, E e) {
if(index <0 || index >= size)
throw new IllegalArgumentException("Get failed. Index is illegal");
data[index] = e;
}
public boolean contains(E e) {
for(int i = 0; i ) {
if(data[i].equals(e))
return true;
}
return false;
}
public int find(E e) {
for(int i = 0; i ) {
if(data[i].equals(e))
return i;
}
return -1;
}
public E remove(int index) {
if(index <0 || index >= size)
throw new IllegalArgumentException("Get failed. Index is illegal");
E res = data[index];
for(int i = index; i) {
data[i] = data[i+1];
}
size--;
//释放空间，也可以不写
//loitering objects != memory leak
data[size] = null;
if(size == data.length / 4 && data.length / 2 != 0)
resize(data.length / 2);
return res;
}
public E removeFirst() {
return remove(0);
}
public E removeLast() {
return remove(size-1);
}
//只删除了一个e，并不能保证删除了全部e
public void removeElement(E e) {
int index = find(e);
if(index != -1)
remove(index);
}
private void resize(int newCapacity) {
E[] newData = (E[]) new Object[newCapacity];
for(int i=0; i ) {
newData[i] = data[i];
}
data = newData;
}
}

定义Stack接口：

package Date_pacage;
public interface Stack {
int getSize();
boolean isEmpty();
void push(E e);
E pop();
E peek();
}

定义ArrayStack：

package Date_pacage;
public class ArrayStack implements Stack {
Array array;
public ArrayStack(int capacity) {
array = new Array<>(capacity);
}
public ArrayStack() {
array = new Array<>();
}
@Override
public int getSize() {
return array.getSize();
}
@Override
public boolean isEmpty() {
return array.isEmpty();
}
public int getCapacity() {
return array.getCapacity();
}
@Override
public void push(E e) {
array.addLast(e);
}
@Override
public E pop() {
return array.removeLast();
}
@Override
public E peek() {
return array.getLast();
}
@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append("STACK:");
res.append("[");
for(int i = 0 ; i ) {
res.append(array.get(i));
if(i != array.getSize()-1)
res.append(", ");
}
res.append("] top");
return res.toString();
}
}