Update StackArrayList.java

yanglbme · web-flow · commit 7c33d2e3132f · 2019-01-06T09:01:33.000+08:00
diff --git a/DataStructures/Stacks/StackArrayList.java b/DataStructures/Stacks/StackArrayList.java
@@ -2,93 +2,94 @@
 
 /**
  * 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
  * 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
  * a problem we can extend the stack as much as we want.
  *
  * @author Unknown
- *
  */
-public class StackArrayList{
+public class StackArrayList {
 
-  /**
-   * Main method
-   *
-   * @param args Command line arguments
-   */
-  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);
+    /**
+     * Main method
+     *
+     * @param args Command line arguments
+     */
+    public static void main(String[] args) {
+        
+        StackArrayList myStackArrayList = new StackArrayList();
+        
+        myStackArrayList.push(5);
+        myStackArrayList.push(8);
+        myStackArrayList.push(2);
+        myStackArrayList.push(9);
 
-    System.out.println("*********************Stack List Implementation*********************");
-    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
-  }
+        System.out.println("*********************Stack List Implementation*********************");
+        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 */
-  private ArrayList<Integer> stackList;
+    /**
+     * ArrayList representation of the stack
+     */
+    private ArrayList<Integer> stackList;
 
-  /**
-   * Constructor
-   */
-  public StackArrayList(){
-    stackList = new ArrayList<>();
-  }
+    /**
+     * Constructor
+     */
+    public StackArrayList() {
+        stackList = new ArrayList<>();
+    }
 
-  /**
-   * 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);
-  }
+    /**
+     * 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(){
+    /**
+     * 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
+        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;
+        }
 
-      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;
     }
 
-    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();
-  }
+    /**
+     * 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);
-  }
-}
+    /**
+     * Top element of stack
+     *
+     * @return top element of stack
+     */
+    public int peek() {
+        return stackList.get(stackList.size() - 1);
+    }
+}
