Java Tutorial/Collections/Search

Binary search

import java.util.Arrays;
import java.util.Random;
public class MainClass {
  private static int[] data = new int[10]; // create space for array
  public static void main(String[] args) {
    Random generator = new Random();
    for (int i = 0; i < 10; i++)
      data[i] = 10 + generator.nextInt(90);
    Arrays.sort(data);
    System.out.println(binarySearch(3));
  }
  public static int binarySearch(int searchElement) {
    int low = 0;
    int high = data.length - 1;
    int middle = (low + high + 1) / 2;
    int location = -1;
    do {
      System.out.print(remainingElements(low, high));
      for (int i = 0; i < middle; i++)
        System.out.print("   ");
      System.out.println(" * ");
      if (searchElement == data[middle])
        location = middle;
      else if (searchElement < data[middle])
        high = middle - 1;
      else
        low = middle + 1;
      middle = (low + high + 1) / 2;
    } while ((low <= high) && (location == -1));
    return location;
  }
  public static String remainingElements(int low, int high) {
    StringBuffer temporary = new StringBuffer();
    for (int i = 0; i < low; i++)
      temporary.append("   ");
    for (int i = low; i <= high; i++)
      temporary.append(data[i] + " ");
    temporary.append("\n");
    return temporary.toString();
  }
}

16 20 31 58 64 75 83 85 86 96 
                * 
16 20 31 58 64 
       * 
16 20 
    * 
16 
 * 
-1

Recursive Binary Search Implementation in Java

public class Main {
  public static final int NOT_FOUND = -1;
  public static int binarySearch(Comparable[] a, Comparable x) {
    return binarySearch(a, x, 0, a.length - 1);
  }
  private static int binarySearch(Comparable[] a, Comparable x, int low, int high) {
    if (low > high)
      return NOT_FOUND;
    int mid = (low + high) / 2;
    if (a[mid].rupareTo(x) < 0)
      return binarySearch(a, x, mid + 1, high);
    else if (a[mid].rupareTo(x) > 0)
      return binarySearch(a, x, low, mid - 1);
    else
      return mid;
  }
  public static void main(String[] args) {
    int SIZE = 8;
    Comparable[] a = new Integer[SIZE];
    for (int i = 0; i < SIZE; i++)
      a[i] = new Integer(i * 2);
    for (int i = 0; i < SIZE * 2; i++)
      System.out.println("Found " + i + " at " + binarySearch(a, new Integer(i)));
  }
}