Java이용해 LinkedList로 Stack구현하기

ListNodeStack.java

package javaStudy.ListNodeStack;

import javaStudy.ListNode.ListNode;

public class ListNodeStack implements Stack{

    ListNode node;
    int top;

    public ListNodeStack(){
        node = null;
        top = 0;
    }

    public ListNode getNode() {
        return node;
    }

    public int getTop() {
        return top;
    }

    @Override
    public boolean push(int data) {
        if(top == 0){
            node = new ListNode(data);
            top++;
        }
        else node.add(new ListNode(data),top++);
        return true;
    }

    @Override
    public int pop() {
        if(top == 0){
            System.out.println("Empty");
            return -1;
        }

        return  node.remove(--top).getKey();
    }
}

ListNodeStackTest.java

package test.ListNodeStack;

import javaStudy.ListNode.ListNode;
import javaStudy.ListNodeStack.ListNodeStack;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

class ListNodeStackTest {
    ListNodeStack listNodeStack;

    @BeforeEach
    void init(){
        listNodeStack = new ListNodeStack();
        listNodeStack.push(1);
        listNodeStack.push(2);
        listNodeStack.push(3);
    }

    @Test
    void add(){
        listNodeStack.push(4);

        ListNode node = listNodeStack.getNode();
        for(int i=1; i < 5; i++ ){
            Assertions.assertEquals(i,node.getKey());
            node = node.getNext();
        }
    }

    @Test
    void removeTest(){
        for(int i =3 ; i > 0 ; i--){
            int result  = listNodeStack.pop();
            Assertions.assertEquals(i,result);
        }
    }
    @Test
    void removeFailTest(){
        for(int i =3 ; i > 0 ; i--){
            int result  = listNodeStack.pop();
            Assertions.assertEquals(i,result);
        }
            int result  = listNodeStack.pop();
            Assertions.assertEquals(-1,result);
    }
}

Stack.java

package javaStudy.ListNodeStack;

public interface Stack {
    boolean push(int data);
    int pop();
}