//
// Created by Julio Tentor <[email protected]>
//
/*
The Stack class represents a last-in-first-out (LIFO) stack of objects.
The usual push and pop operations are provided, as well as a method to
peek at the top item on the stack, a method to test for whether the
stack is empty, and a method to search the stack for an item and discover
how far it is from the top.
When a stack is first created, it contains no items.
from https://docs.oracle.com/en/java/javase/13/docs/api/java.base/java/util/Stack.html
from https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/util/Stack.html
from https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/util/Stack.html
*/
public class Stack<ELEMENT> {
//region Constants
private final static Integer defaulDimension = 10;
//endregion
//region Attributes
private ELEMENT [] data;
private Integer count;
//endregion
//region Constructors
public Stack() {
this(Stack.defaulDimension);
}
public Stack(Integer dimension) {
if (dimension <= 0) {
throw new RuntimeException("La cantidad de elementos en la pila debe ser positiva");
}
this.data = (ELEMENT []) new Object[dimension];
this.count = 0;
}
//endregion
//region Stack Methods
// Test if this stack is empty.
public boolean empty() {
return this.count <= 0;
}
// Looks at the object at the top of this stack without removing it from the stack.
public ELEMENT peek() {
if (this.empty()) {
throw new RuntimeException("La pila está vacía...");
}
return this.data[this.count - 1];
}
// Removes the object at the top of this stack and returns that object as the value of this function.
public ELEMENT pop() {
if (this.empty()) {
throw new RuntimeException("La pila está vacía...");
}
--this.count;
return this.data[this.count];
}
// Pushes an item onto the top of this stack.
public ELEMENT push(ELEMENT element) {
if (this.size() >= this.data.length) {
// throw new RuntimeException("La pila está llena...");
ELEMENT [] temp = (ELEMENT []) new Object[this.data.length * 2];
for (int i = 0; i < this.data.length; ++i) {
temp[i] = this.data[i];
}
this.data = temp;
}
this.data[this.count] = element;
++this.count;
return element;
}
// Returns the 1-based position where an object is on this stack.
public int search(Object object) {
for (int pos = this.count - 1; pos >= 0; --pos) {
if (this.data[pos].equals(object)) {
return this.count - pos;
}
}
return -1;
}
//endregion
//region Inherited Methods
// from https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/util/Vector.html
// Returns the number of components in this vector.
public int size() {
return this.count;
}
//endregion
//region Override Object basic methods
@Override
public String toString() {
if (this.size() <=0) {
return "";
}
// from https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/lang/StringBuilder.html
StringBuilder sb = new StringBuilder();
sb.append("[" + this.data[0].toString());
for (int i = 1; i < this.size(); ++i) {
sb.append(", " + this.data[i].toString());
}
sb.append("]");
return sb.toString();
}
//endregion
}
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