StackArray.java

//Sklad s poljem
 
public class StackArray implements Stack {
    static final int DEFAULT_LENGTH = 100 ;
    private Object elements[] ;
    private int stTop ; ;
 
    public StackArray() {
      this(DEFAULT_LENGTH) ;
    }
    public StackArray(int noElem) {
      elements = new Object[noElem] ;
      makenull() ;
    }
    public void makenull() {
      stTop = -1 ;
    }
 
    public boolean empty() {
      return stTop ==-1 ;
    }
 
    public Object top() {
      if (empty()) // error
        ; // throw new UnderflowException ;
      return elements[stTop] ;
    }
    public void push(Object x) {
      stTop++ ;
      if (stTop >= elements.length) //error: full
        ; // throw new OverflowException ;
      else {
        elements[stTop] = x ;
      }
    }
    public void pop() {
      if (empty()) // error
        ; // throw new UnderflowException ;
      else stTop-- ;
    }
 
    public static void main(String[] args) {
      StackArray s = new StackArray();
      System.out.println("Testing class "+s.getClass() );
      int i ;
      for (i=1 ; i <= 5 ; i++) {
        s.push(new Integer(i));
        System.out.println("Pushing " + i) ;
      }
      while (!s.empty()) {
        System.out.println("Poping "+s.top());
        s.pop() ;
      }
   }
}