Java Collections - ArrayList.subList() Examples

Java Collections Java Java API 

Class:

java.util.ArrayList

Methods:

public List<E> subList (int fromIndex, int toIndex)

Returns a view of the portion of this list between the specified fromIndex, inclusive, and toIndex, exclusive. (If fromIndex and toIndex are equal, the returned list is empty.) The returned list is backed by this list, so non-structural changes in the returned list are reflected in this list, and vice-versa. The returned list supports all of the optional list operations.

This method eliminates the need for explicit range operations (of the sort that commonly exist for arrays). Any operation that expects a list can be used as a range operation by passing a subList view instead of a whole list. For example, the following idiom removes a range of elements from a list:

 list.subList(from, to).clear(); 

The semantics of the list returned by this method become undefined if the backing list (i.e., this list) is structurally modified in any way other than via the returned list. (Structural modifications are those that change the size of this list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.)

Examples

package com.logicbig.example.arraylist;

import java.util.*;

public class SubListExample {

    public static void main(String... args) {
        // Create view of portion of list
        ArrayList<String> list = new ArrayList<>(Arrays.asList("A","B","C","D","E"));
        List<String> sub = list.subList(1, 4);
        System.out.println("Sublist (1,4): " + sub);
        sub.set(0, "B-New");
        System.out.println("Original after modification: " + list);
    }
}

Output

Sublist (1,4): [B, C, D]
Original after modification: [A, B-New, C, D, E]

JDK 25