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Update StackArrayList.java

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This commit is contained in:
Libin Yang
2019-01-06 09:01:33 +08:00
committed by GitHub
parent fc64d05b5c
commit 7c33d2e313
1 changed files with 78 additions and 77 deletions
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149
DataStructures/Stacks/StackArrayList.java
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@ -2,93 +2,94 @@ import java.util.ArrayList;
/** /**
* This class implements a Stack using an ArrayList. * This class implements a Stack using an ArrayList.
* * <p>
* A stack is exactly what it sounds like. An element gets added to the top of * A stack is exactly what it sounds like. An element gets added to the top of
* the stack and only the element on the top may be removed. * the stack and only the element on the top may be removed.
* * <p>
* This is an ArrayList Implementation of a stack, where size is not * This is an ArrayList Implementation of a stack, where size is not
* a problem we can extend the stack as much as we want. * a problem we can extend the stack as much as we want.
* *
* @author Unknown * @author Unknown
*
*/ */
public class StackArrayList{ public class StackArrayList {
/** /**
* Main method * Main method
* *
* @param args Command line arguments * @param args Command line arguments
*/ */
public static void main(String[] args) { public static void main(String[] args) {
StackArrayList myStackArrayList = new StackArrayList(); //Declare a stack of maximum size 4
//Populate the stack
myStackArrayList.push(5);
myStackArrayList.push(8);
myStackArrayList.push(2);
myStackArrayList.push(9);
System.out.println("*********************Stack List Implementation*********************"); StackArrayList myStackArrayList = new StackArrayList();
System.out.println(myStackArrayList.isEmpty()); //will print false
System.out.println(myStackArrayList.peek()); //will print 9
System.out.println(myStackArrayList.pop()); //will print 9
System.out.println(myStackArrayList.peek()); // will print 2
System.out.println(myStackArrayList.pop()); //will print 2
}
/** ArrayList representation of the stack */ myStackArrayList.push(5);
private ArrayList<Integer> stackList; myStackArrayList.push(8);
myStackArrayList.push(2);
myStackArrayList.push(9);
/** System.out.println("*********************Stack List Implementation*********************");
* Constructor System.out.println(myStackArrayList.isEmpty()); // will print false
*/ System.out.println(myStackArrayList.peek()); // will print 9
public StackArrayList(){ System.out.println(myStackArrayList.pop()); // will print 9
stackList = new ArrayList<>(); System.out.println(myStackArrayList.peek()); // will print 2
} System.out.println(myStackArrayList.pop()); // will print 2
/**
* Adds value to the end of list which
* is the top for stack
*
* @param value value to be added
*/
public void push(int value){
stackList.add(value);
}
/**
* Pops last element of list which is indeed
* the top for Stack
*
* @return Element popped
*/
public int pop(){
if(!isEmpty()){ // checks for an empty Stack
int popValue=stackList.get(stackList.size()-1);
stackList.remove(stackList.size()-1); //removes the poped element from the list
return popValue;
} }
System.out.print("The stack is already empty "); /**
return -1; * ArrayList representation of the stack
} */
private ArrayList<Integer> stackList;
/** /**
* Checks for empty Stack * Constructor
* */
* @return true if stack is empty public StackArrayList() {
*/ stackList = new ArrayList<>();
public boolean isEmpty(){ }
return stackList.isEmpty();
}
/** /**
* Top element of stack * Adds value to the end of list which
* * is the top for stack
* @return top element of stack *
*/ * @param value value to be added
public int peek(){ */
return stackList.get(stackList.size()-1); public void push(int value) {
} stackList.add(value);
}
/**
* Pops last element of list which is indeed
* the top for Stack
*
* @return Element popped
*/
public int pop() {
if (!isEmpty()) { // checks for an empty Stack
int popValue = stackList.get(stackList.size() - 1);
stackList.remove(stackList.size() - 1); // removes the poped element from the list
return popValue;
}
System.out.print("The stack is already empty!");
return -1;
}
/**
* Checks for empty Stack
*
* @return true if stack is empty
*/
public boolean isEmpty() {
return stackList.isEmpty();
}
/**
* Top element of stack
*
* @return top element of stack
*/
public int peek() {
return stackList.get(stackList.size() - 1);
}
} }