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| 1 | // | |
| 2 | // Created by Julio Tentor <[email protected]> | |
| 3 | // | |
| 4 | ||
| 5 | ||
| 6 | /* | |
| 7 | The Stack class represents a last-in-first-out (LIFO) stack of objects. | |
| 8 | ||
| 9 | The usual push and pop operations are provided, as well as a method to | |
| 10 | peek at the top item on the stack, a method to test for whether the | |
| 11 | stack is empty, and a method to search the stack for an item and discover | |
| 12 | how far it is from the top. | |
| 13 | ||
| 14 | When a stack is first created, it contains no items. | |
| 15 | ||
| 16 | from https://docs.oracle.com/en/java/javase/13/docs/api/java.base/java/util/Stack.html | |
| 17 | from https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/util/Stack.html | |
| 18 | from https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/util/Stack.html | |
| 19 | ||
| 20 | */ | |
| 21 | public class Stack<ELEMENT> {
| |
| 22 | ||
| 23 | //region Constants | |
| 24 | ||
| 25 | private final static Integer defaulDimension = 10; | |
| 26 | ||
| 27 | //endregion | |
| 28 | ||
| 29 | //region Attributes | |
| 30 | ||
| 31 | private ELEMENT [] data; | |
| 32 | private Integer count; | |
| 33 | ||
| 34 | //endregion | |
| 35 | ||
| 36 | //region Constructors | |
| 37 | ||
| 38 | public Stack() {
| |
| 39 | this(Stack.defaulDimension); | |
| 40 | } | |
| 41 | public Stack(Integer dimension) {
| |
| 42 | if (dimension <= 0) {
| |
| 43 | throw new RuntimeException("La cantidad de elementos en la pila debe ser positiva");
| |
| 44 | } | |
| 45 | this.data = (ELEMENT []) new Object[dimension]; | |
| 46 | this.count = 0; | |
| 47 | } | |
| 48 | ||
| 49 | //endregion | |
| 50 | ||
| 51 | //region Stack Methods | |
| 52 | ||
| 53 | // Test if this stack is empty. | |
| 54 | public boolean empty() {
| |
| 55 | return this.count <= 0; | |
| 56 | } | |
| 57 | ||
| 58 | // Looks at the object at the top of this stack without removing it from the stack. | |
| 59 | public ELEMENT peek() {
| |
| 60 | if (this.empty()) {
| |
| 61 | throw new RuntimeException("La pila está vacía...");
| |
| 62 | } | |
| 63 | return this.data[this.count - 1]; | |
| 64 | } | |
| 65 | ||
| 66 | // Removes the object at the top of this stack and returns that object as the value of this function. | |
| 67 | public ELEMENT pop() {
| |
| 68 | if (this.empty()) {
| |
| 69 | throw new RuntimeException("La pila está vacía...");
| |
| 70 | } | |
| 71 | --this.count; | |
| 72 | return this.data[this.count]; | |
| 73 | } | |
| 74 | ||
| 75 | // Pushes an item onto the top of this stack. | |
| 76 | public ELEMENT push(ELEMENT element) {
| |
| 77 | if (this.size() >= this.data.length) {
| |
| 78 | // throw new RuntimeException("La pila está llena...");
| |
| 79 | ||
| 80 | ELEMENT [] temp = (ELEMENT []) new Object[this.data.length * 2]; | |
| 81 | for (int i = 0; i < this.data.length; ++i) {
| |
| 82 | temp[i] = this.data[i]; | |
| 83 | } | |
| 84 | this.data = temp; | |
| 85 | } | |
| 86 | this.data[this.count] = element; | |
| 87 | ++this.count; | |
| 88 | return element; | |
| 89 | } | |
| 90 | ||
| 91 | // Returns the 1-based position where an object is on this stack. | |
| 92 | public int search(Object object) {
| |
| 93 | for (int pos = this.count - 1; pos >= 0; --pos) {
| |
| 94 | if (this.data[pos].equals(object)) {
| |
| 95 | return this.count - pos; | |
| 96 | } | |
| 97 | } | |
| 98 | return -1; | |
| 99 | } | |
| 100 | //endregion | |
| 101 | ||
| 102 | //region Inherited Methods | |
| 103 | ||
| 104 | // from https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/util/Vector.html | |
| 105 | // Returns the number of components in this vector. | |
| 106 | public int size() {
| |
| 107 | return this.count; | |
| 108 | } | |
| 109 | ||
| 110 | //endregion | |
| 111 | ||
| 112 | ||
| 113 | ||
| 114 | //region Override Object basic methods | |
| 115 | ||
| 116 | @Override | |
| 117 | public String toString() {
| |
| 118 | ||
| 119 | if (this.size() <=0) {
| |
| 120 | return ""; | |
| 121 | } | |
| 122 | ||
| 123 | // from https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/lang/StringBuilder.html | |
| 124 | StringBuilder sb = new StringBuilder(); | |
| 125 | sb.append("[" + this.data[0].toString());
| |
| 126 | for (int i = 1; i < this.size(); ++i) {
| |
| 127 | sb.append(", " + this.data[i].toString());
| |
| 128 | } | |
| 129 | sb.append("]");
| |
| 130 | return sb.toString(); | |
| 131 | } | |
| 132 | //endregion | |
| 133 | ||
| 134 | ||
| 135 | } | |
| 136 |