Safe sub list operation - Java java.util

Java examples for java.util:List Sub List

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Description

Safe sub list operation

Demo Code


//package com.book2s;

import java.util.ArrayList;
import java.util.Collection;

import java.util.List;

public class Main {
    public static void main(String[] argv) {
        List list = java.util.Arrays.asList("asdf", "book2s.com");
        int start = 42;
        int end = 42;
        System.out.println(sub(list, start, end));
    }/* w ww  .  ja  v  a 2s.  co  m*/

    public static <T> List<T> sub(List<T> list, int start, int end) {
        if (list == null || list.isEmpty()) {
            return null;
        }

        if (start < 0) {
            start = 0;
        }
        if (end < 0) {
            end = 0;
        }

        if (start > end) {
            int tmp = start;
            start = end;
            end = tmp;
        }

        final int size = list.size();
        if (end > size) {
            if (start >= size) {
                return null;
            }
            end = size;
        }

        return list.subList(start, end);
    }

    public static <T> List<T> sub(Collection<T> list, int start, int end) {
        if (list == null || list.isEmpty()) {
            return null;
        }

        return sub(new ArrayList<T>(list), start, end);
    }

    public static <T> boolean isEmpty(T[] array) {
        return array == null || array.length == 0;
    }

    public static <T> boolean isEmpty(Collection<T> collection) {
        return collection == null || collection.isEmpty();
    }
}

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