CODEWITHSUNDEEP
java
陈俊杰
陈俊杰

Reputation: 31

there is a problem in the output of my java code

There is a problem in the output of my java code. In the tipOdd part, I want to remove the element in index 0 and odd index of an arraylist. For example, an arraylist [40 8 6 3 7 5 2], and then the expected output should be [6 7 2],but my code output is [6 3 7 5 2 6 7 2]. Can anyone can help me to solve the problem. I am very appreciate your help!

Code:
import java.io.*;
import java.util.*;
import java.util.ArrayList;

class ArrayLinearListRev extends ArrayLinearList{
public ArrayList<Integer> reverse(ArrayList<Integer> alist)
{
        ArrayList<Integer> revArrayList = new ArrayList<Integer>();
        for (int i = alist.size() - 1; i >= 0; i -- ) {
            revArrayList.add(alist.get(i));
        }

        return revArrayList;
}

public void printElements(ArrayList<Integer> alist)
{
        for (int i = 0; i < alist.size(); i++) {
            System.out.print(alist.get(i) + " ");
        }
}

public ArrayList<Integer> leftSh(int post, ArrayList<Integer> alist2)
{
   ArrayList<Integer> LeftshifedList = new ArrayList<Integer>(alist2);
   for (int i = 1; i <= post; i++)
   {
       LeftshifedList.remove(0);
   }

   return LeftshifedList;

 }

public void printElements2(ArrayList<Integer> alist2)
{
    for (int i = 0; i < alist2.size(); i++) {
        System.out.print(alist2.get(i) + " ");
    }
}

public ArrayList<Integer> tipOdd(ArrayList<Integer> alist3)
{
    ArrayList<Integer> removeOdd = new ArrayList<Integer>(alist3);
    for (int i = 0; i < alist3.size(); i++)
    {
        if (i == 0 || i%2 == 0){
            removeOdd.add(alist3.get(i));
        }
    }

 return removeOdd;
 }

public void printElements3(ArrayList<Integer> alist3)
{
    for (int i = 0; i < alist3.size(); i++) {
        System.out.print(alist3.get(i) + " ");
    }
   }

}

public class ArrayLinearListFun  
{
public static void main(String[] args)
  {
    ArrayLinearListRev obj = new ArrayLinearListRev();
    ArrayList<Integer> x = new ArrayList<Integer>();
    x.add(0, new Integer(2));
    x.add(1, new Integer(5));
    x.add(2, new Integer(7));
    x.add(3, new Integer(3));
    x.add(4, new Integer(6));
    x.add(5, new Integer(8));
    x.add(6, new Integer(40));

    System.out.print("The list is: ");
    obj.printElements(x);

    x = obj.reverse(x);
    System.out.print("\nThe list is: ");
    obj.printElements(x);

     x=obj.leftSh(2, x);
     System.out.print("\nThe list is: ");
     obj.printElements2(x);


    x=obj.tipOdd(x);
    System.out.print("\nThe list is: ");
    obj.printElements3(x);
}
}

Upvotes: 0

Views: 187

Answers (1)

Anonymous
Anonymous

Reputation: 86120

I have not gone through all of your code. But concerning your tipOdd method: You first create a new list, removeOdd containing all the elements from the original list, alist3. If the original list was [10, 2, 3], then the new list is [10, 2, 3] from the outset. Next you add to the new list all the elements in even indices in the original list. So [10, 2, 3] gets expanded to [10, 2, 3, 10, 3].

Instead I suggest you start out from an empty list. Just remove the argument to new ArrayList<Integer> in the first line of the method. Then to this empty list add the elements that you want to keep from the original list.

Your condition i == 0 || i%2 == 0 may not be quite what you want. When i is 0, i % 2 is 0 too, so the first part makes no difference. If you did not want the element at index 0 included in the new list, consider i != 0 && i % 2 == 0.

Upvotes: 1

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