Lower_bound(), upper_bound() functions for sorted containers

Question

I can't find lower_bound(), upper_bound() functions for sorted containers in the java library. It doesn't seem to be there in the apache commons either.
i'm referring here to the meaning as defined in STL (C++) as in:
http://www.cplusplus.com/reference/algorithm/lower_bound/
http://www.cplusplus.com/reference/algorithm/upper_bound/
These functions are extremely useful for range lookups. Why is this not readily available in the java libraries?

Answer 1

How I would write the Java code for the problem you stated on the blog:
import java.util.Arrays;
import java.util.NavigableMap;
import java.util.TreeMap;
import java.util.Map.Entry;
public class TestNavigable {
    public static void main(String[] args) {
        NavigableMap<Integer, Integer> map = new TreeMap<Integer, Integer>();
        map.put(10, 100);
        map.put(25, 212);
        map.put(30, 212);
        map.put(200, 400);
        for (int check : new int[] { -1, 0, 5, 11, 26, 30, 100, 400 }) {
            Entry<Integer, Integer> upper = map.ceilingEntry(check);
            if (upper != null) {
                Integer lower = map.lowerKey(upper.getKey());
                if(lower == null) {
                    System.out.println(check + " falls into range up to "
                            + upper.getKey() + " and maps to " + upper.getValue());
                else {
                    System.out.println(check + " falls into range <" + lower + ", "
                            + upper.getKey() + "] and maps to " + upper.getValue());
            else {
                System.out.println(check + " is out of range!");
        // if you want to use arrays for other reasons
        // note: would require to keep keys/values in sync if not sorted
        int[] keys = { 10, 25, 30, 200 };
        int[] values = { 100, 212, 212, 400 };
        for (int check : new int[] { -1, 0, 5, 11, 26, 30, 100, 400 }) {
            int index = Arrays.binarySearch(keys, check);
            if(index < 0) {
                index = -(index + 1);
            // good enough if no duplicate elements in keys
            // see binarySearch javadoc
            int lower = index - 1;
            int upper = index;
            if (upper < values.length) {
                if(lower == -1) {
                    System.out.println(check + " falls into range up to "
                            + keys[upper] + " and maps to " + values[upper]);
                else {
                    System.out.println(check + " falls into range <" + keys[lower] + ", "
                            + keys[upper] + "] and maps to " + values[upper]);
            else {
                System.out.println(check + " is out of range!");
}I'm too spoiled to write a binary search like you did ;-).