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Format code in StackArray
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‎DataStructures/Stacks/StackArray.java‎

Lines changed: 133 additions & 127 deletions
Original file line numberDiff line numberDiff line change
@@ -1,146 +1,152 @@
11
/**
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* This class implements a Stack using a regular array.
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*
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* <p>
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* A stack is exactly what it sounds like. An element gets added to the top of
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* the stack and only the element on the top may be removed. This is an example
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* of an array implementation of a Stack. So an element can only be added/removed
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* from the end of the array. In theory stack have no fixed size, but with an
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* array implementation it does.
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*
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* @author Unknown
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*
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*/
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public class StackArray{
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/**
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* Main method
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*
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* @param args Command line arguments
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*/
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public static void main(String[] args) {
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StackArray myStackArray = new StackArray(4); //Declare a stack of maximum size 4
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//Populate the stack
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myStackArray.push(5);
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myStackArray.push(8);
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myStackArray.push(2);
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myStackArray.push(9);
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System.out.println("*********************Stack Array Implementation*********************");
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System.out.println(myStackArray.isEmpty()); //will print false
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System.out.println(myStackArray.isFull()); //will print true
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System.out.println(myStackArray.peek()); //will print 9
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System.out.println(myStackArray.pop()); //will print 9
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System.out.println(myStackArray.peek()); // will print 2
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}
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/** The max size of the Stack */
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private int maxSize;
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/** The array representation of the Stack */
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private int[] stackArray;
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/** The top of the stack */
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private int top;
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/**
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* Constructor
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*
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* @param size Size of the Stack
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*/
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public StackArray(int size){
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maxSize = size;
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stackArray = new int[maxSize];
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top = -1;
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}
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/**
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* Adds an element to the top of the stack
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*
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* @param value The element added
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*/
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public void push(int value){
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if(!isFull()){ //Checks for a full stack
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top++;
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stackArray[top] = value;
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}else{
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resize(maxSize*2);
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push(value);// don't forget push after resizing
12+
public class StackArray {
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/**
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* Main method
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*
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* @param args Command line arguments
18+
*/
19+
public static void main(String[] args) {
20+
// Declare a stack of maximum size 4
21+
StackArray myStackArray = new StackArray(4);
22+
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// Populate the stack
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myStackArray.push(5);
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myStackArray.push(8);
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myStackArray.push(2);
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myStackArray.push(9);
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System.out.println("*********************Stack Array Implementation*********************");
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System.out.println(myStackArray.isEmpty()); // will print false
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System.out.println(myStackArray.isFull()); // will print true
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System.out.println(myStackArray.peek()); // will print 9
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System.out.println(myStackArray.pop()); // will print 9
34+
System.out.println(myStackArray.peek()); // will print 2
35+
}
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/**
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* The max size of the Stack
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*/
40+
private int maxSize;
41+
42+
/**
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* The array representation of the Stack
44+
*/
45+
private int[] stackArray;
46+
47+
/**
48+
* The top of the stack
49+
*/
50+
private int top;
51+
52+
/**
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* Constructor
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*
55+
* @param size Size of the Stack
56+
*/
57+
public StackArray(int size) {
58+
maxSize = size;
59+
stackArray = new int[maxSize];
60+
top = -1;
6861
}
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}
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/**
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* Removes the top element of the stack and returns the value you've removed
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*
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* @return value popped off the Stack
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*/
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public int pop(){
77-
if(!isEmpty()){ //Checks for an empty stack
78-
return stackArray[top--];
62+
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/**
64+
* Adds an element to the top of the stack
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*
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* @param value The element added
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*/
68+
public void push(int value) {
69+
if (!isFull()) { // Checks for a full stack
70+
top++;
71+
stackArray[top] = value;
72+
} else {
73+
resize(maxSize * 2);
74+
push(value); // don't forget push after resizing
75+
}
7976
}
8077

81-
if(top < maxSize/4){
82-
resize(maxSize/2);
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return pop();// don't forget pop after resizing
78+
/**
79+
* Removes the top element of the stack and returns the value you've removed
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*
81+
* @return value popped off the Stack
82+
*/
83+
public int pop() {
84+
if (!isEmpty()) { // Checks for an empty stack
85+
return stackArray[top--];
86+
}
87+
88+
if (top < maxSize / 4) {
89+
resize(maxSize / 2);
90+
return pop();// don't forget pop after resizing
91+
} else {
92+
System.out.println("The stack is already empty");
93+
return -1;
94+
}
8495
}
85-
else{
86-
System.out.println("The stack is already empty");
87-
return -1;
96+
97+
/**
98+
* Returns the element at the top of the stack
99+
*
100+
* @return element at the top of the stack
101+
*/
102+
public int peek() {
103+
if (!isEmpty()) { // Checks for an empty stack
104+
return stackArray[top];
105+
} else {
106+
System.out.println("The stack is empty, cant peek");
107+
return -1;
108+
}
88109
}
89-
}
90-
91-
/**
92-
* Returns the element at the top of the stack
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*
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* @return element at the top of the stack
95-
*/
96-
public int peek(){
97-
if(!isEmpty()){ //Checks for an empty stack
98-
return stackArray[top];
99-
}else{
100-
System.out.println("The stack is empty, cant peek");
101-
return -1;
110+
111+
private void resize(int newSize) {
112+
// private int[] transferArray = new int[newSize]; we can't put modifiers here !
113+
int[] transferArray = new int[newSize];
114+
115+
// for(int i = 0; i < stackArray.length(); i++){ the length isn't a method .
116+
for (int i = 0; i < stackArray.length; i++) {
117+
transferArray[i] = stackArray[i];
118+
stackArray = transferArray;
119+
}
120+
maxSize = newSize;
121+
}
122+
123+
/**
124+
* Returns true if the stack is empty
125+
*
126+
* @return true if the stack is empty
127+
*/
128+
public boolean isEmpty() {
129+
return (top == -1);
102130
}
103-
}
104131

105-
private void resize(int newSize){
106-
//private int[] transferArray = new int[newSize]; we can't put modifires here !
107-
int[] transferArray = new int[newSize];
132+
/**
133+
* Returns true if the stack is full
134+
*
135+
* @return true if the stack is full
136+
*/
137+
public boolean isFull() {
138+
return (top + 1 == maxSize);
139+
}
108140

109-
//for(int i = 0; i < stackArray.length(); i++){ the length isn't a method .
110-
for(int i = 0; i < stackArray.length; i++){
111-
transferArray[i] = stackArray[i];
112-
stackArray = transferArray;
141+
/**
142+
* Deletes everything in the Stack
143+
* <p>
144+
* Doesn't delete elements in the array
145+
* but if you call push method after calling
146+
* makeEmpty it will overwrite previous
147+
* values
148+
*/
149+
public void makeEmpty() { // Doesn't delete elements in the array but if you call
150+
top = -1; // push method after calling makeEmpty it will overwrite previous values
113151
}
114-
maxSize = newSize;
115-
}
116-
117-
/**
118-
* Returns true if the stack is empty
119-
*
120-
* @return true if the stack is empty
121-
*/
122-
public boolean isEmpty(){
123-
return(top == -1);
124-
}
125-
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/**
127-
* Returns true if the stack is full
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*
129-
* @return true if the stack is full
130-
*/
131-
public boolean isFull(){
132-
return(top+1 == maxSize);
133-
}
134-
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/**
136-
* Deletes everything in the Stack
137-
*
138-
* Doesn't delete elements in the array
139-
* but if you call push method after calling
140-
* makeEmpty it will overwrite previous
141-
* values
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*/
143-
public void makeEmpty(){ //Doesn't delete elements in the array but if you call
144-
top = -1; //push method after calling makeEmpty it will overwrite previous values
145-
}
146-
}
152+
}

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