Java二分查找算法详解与实现

// orderedArray.java
// demonstrates ordered array class
// to run this program: C>java OrderedApp
////////////////////////////////////////////////////////////////
class OrdArray
{
   private long[] a;                 // ref to array a
   private int nElems;               // number of data items
   static int count=0; 
   //-----------------------------------------------------------
   public OrdArray(int max)          // constructor
   {
      a = new long[max];             // create array
      nElems = 0;
    }
   //-----------------------------------------------------------
   public int size()
      { return nElems; }
   //-----------------------------------------------------------
   public int find(long searchKey)
   {   //count++;
      int lowerBound = 0;
      int upperBound = nElems-1;
 //     int curIn;

      while(true)
      {  
         int curIn = (lowerBound + upperBound ) / 2;
         if(a[curIn]==searchKey)
            return curIn;              // found it

         else if(lowerBound > upperBound)
            return nElems;             // can't find it
         else                          // divide range
         {
            if(a[curIn] < searchKey)
               lowerBound = curIn + 1; // it's in upper half
            else
               upperBound = curIn - 1; // it's in lower half
         }  // end else divide range
      }  // end while
    }  // end find()
   //-----------------------------------------------------------
   public void insert(long value)    // put element into array
      {
      int j;
      for(j=0; j<nElems; j++)        // find where it goes
         if(a[j] > value)            // (linear search)
            break;
      for(int k=nElems; k>j; k--)    // move bigger ones up
         a[k] = a[k-1];
      a[j] = value;                  // insert it
      nElems++;                      // increment size
      }  // end insert()
   //-----------------------------------------------------------
   public boolean delete(long value)
      {
      int j = find(value);
      if(j==nElems)                  // can't find it
         return false;
      else                           // found it