Update Stack.java

Format code
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yanglbme 2019-03-16 15:08:57 +08:00 committed by GitHub
parent 27753bb8d1
commit 46df09ab86
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@ -3,17 +3,17 @@ package src.main.java.com.dataStructures;
import java.io.Serializable;
import java.util.EmptyStackException;
public class Stack<E> implements Serializable {
public class Stack<E> implements Serializable {
/**
* Inital capacity alloted to stack on object creation
* Initial capacity allocated to stack on object creation
*/
private final int INITIAL_CAPACITY = 10;
/**
* Increment in memory space once stack is out of space
*/
private final int EXNTEDED_CAPACITY = 10;
private final int EXTENDED_CAPACITY = 10;
/**
@ -30,15 +30,14 @@ public class Stack<E> implements Serializable {
/**
* Uninitialized array to hold stack elements.
* WIll be intialized with inital capacity once the object is created
* WIll be initialized with initial capacity once the object is created
*/
private Object[] elements;
/**
* No argument to create stack object with inital capacity
* No argument to create stack object with initial capacity
*/
public Stack() {
elements = new Object[INITIAL_CAPACITY];
}
@ -47,16 +46,7 @@ public class Stack<E> implements Serializable {
*/
public boolean empty() {
if(null == elements) {
return true;
}
if(size == 0){
return true;
}
return false;
return elements == null || size == 0;
}
@ -65,12 +55,11 @@ public class Stack<E> implements Serializable {
*/
public Object peek() {
if (empty()) {
throw new EmptyStackException();
}
if(empty()) {
throw new EmptyStackException();
}
return elements[tail];
return elements[tail];
}
/**
@ -78,8 +67,7 @@ public class Stack<E> implements Serializable {
*/
public Object pop() {
if(empty()) {
if (empty()) {
throw new EmptyStackException();
}
@ -95,12 +83,12 @@ public class Stack<E> implements Serializable {
public Object push(Object e) {
boolean isSuccess = false;
if(tail < (INITIAL_CAPACITY - 1)){
if (tail < (INITIAL_CAPACITY - 1)) {
tail++;
elements[tail] = e;
}else{
Object[] extendedElements = new Object[INITIAL_CAPACITY + EXNTEDED_CAPACITY];
System.arraycopy(elements, 0, extendedElements, 0, (tail+1));
} else {
Object[] extendedElements = new Object[INITIAL_CAPACITY + EXTENDED_CAPACITY];
System.arraycopy(elements, 0, extendedElements, 0, (tail + 1));
elements = extendedElements;
tail++;
elements[tail] = e;
@ -118,19 +106,19 @@ public class Stack<E> implements Serializable {
int index = -1;
boolean found = false;
if(empty()) {
if (empty()) {
return -1;
}
for(int i=0; i<size();i++) {
if(elements[i] == o) {
for (int i = 0; i < size(); i++) {
if (elements[i] == o) {
index = i;
found = true;
break;
}
}
if(found) {
if (found) {
index = tail - index + 1;
}
@ -143,5 +131,4 @@ public class Stack<E> implements Serializable {
public int size() {
return size;
}
}