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I am coming from a C++ background. I use vector push_back and pop_back methods to push and pop out elements from the vector. I know arraylist is sort of equivalent to vector, but I don'f find equivalent methods to push_back and pop_back in arraylist API. The closet I could find is LinkedList. Am I missing something or is there any other equivalent to vector in C++?

Any help is appreciated.

nikhil
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  • Is a [`Stack`](http://docs.oracle.com/javase/7/docs/api/java/util/Stack.html) what you're looking for? – RaminS Mar 27 '17 at 19:50
  • I think you want a [`Deque`](https://docs.oracle.com/javase/7/docs/api/java/util/Deque.html). – Elliott Frisch Mar 27 '17 at 19:51
  • maybe `add()` and `remove()`? Source: https://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html – Galik Mar 27 '17 at 19:52
  • C++ vector givesadditional functionality of accessing elements randomly (Since vector is internally an array). Stack does not allow such random access – nikhil Mar 27 '17 at 19:58
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    Possible duplicate of [Equivalent of std::vector in Java?](http://stackoverflow.com/questions/3731067/equivalent-of-stdvector-in-java) – user4581301 Mar 27 '17 at 19:59

4 Answers4

16

Use add() from ArrayList to push_back.

For pop_back you have to play around a bit more with indexes and remove().

Let's look at this example:

// push_back equivalent
ArrayList<int> a = new ArrayList<int>();
a.add(2);             // Add element to the ArrayList.
a.add(4);

// pop_back equivalent.
a.remove(a.size()-1); // Remove the last element from the ArrayList.
Santiago Varela
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3

Use ArrayList for dynamically add and remove element.

For push_back() use .add()

add() method to add elements in the list

List<Integer> arrlist = new ArrayList<Integer>(); 
arrlist.add(10);

For pop_back() use .remove()

remove() used for removing the element at the specified position in this list. So, pass last index in method to delete last element

arrlist.remove(arrlist.size() - 1);
Eklavya
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2

We can use the LinkedList<E> data structure

Adding at the end by: add(E e)

removing at the end by using: pollLast()

Example:

package test;

import java.util.*;  
public class test{  
public static void main(String args[]){  

    LinkedList<String> al=new LinkedList<String>();  
    al.add("element1");  
    al.add("element2");  
    al.add("element3");  

    Iterator<String> itr=al.iterator();  
    while(itr.hasNext()){  
        System.out.print(itr.next()+" ");  
    } 

    System.out.println(" ");

    al.add("element4");  

    itr=al.iterator();  
    while(itr.hasNext()){  
        System.out.print(itr.next()+ " "); 
    } 
    System.out.println(" ");

    //pop_back
    al.pollLast();

    itr=al.iterator();  
    while(itr.hasNext()){  
        System.out.print(itr.next()+" ");  
      }  
    }  
}

result:

element1 element2 element3  
element1 element2 element3 element4  
element1 element2 element3
HDJEMAI
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1

You can use add() for push_back() and remove() for pop_back().

ArrayList<data_type> data = new ArrayList<data_type>();
data.add(value1);
data.add(value2);
data.remove(data.size() - 1);

P.S : arraylist is a container not API.

Shravan40
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