Java.util.Arrays.binarySearch(byte[] a, int fromIndex, int toIndex, byte key)方法实例

描述

The java.util.Arrays.binarySearch(byte[] a, int fromIndex, int toIndex, byte key) method searches a range of the specified array of bytes for the specified value using the binary search algorithm. The range must be sorted before making this call.If it is not sorted, the results are undefined.

声明

Following is the declaration for java.util.Arrays.binarySearch() method

public static int binarySearch(byte[] a, int fromIndex, int toIndex, byte key)

参数

• a -- This is the array to be searched.

• fromIndex -- This is the index of the first element (inclusive) to be searched.

• toIndex -- This is the index of the last element (exclusive) to be searched.

• key -- This is the value to be searched for.

返回值

This method returns index of the search key, if it is contained in the array, else it returns (-(insertion point) - 1). The insertion point is the point at which the key would be inserted into the array; the index of the first element in the range greater than the key, or toIndex if all elements in the range are less than the specified key.

异常

• IllegalArgumentException -- if fromIndex > toIndex

• ArrayIndexOutOfBoundsException -- if fromIndex < 0 or toIndex > a.length

实例一

以下例子将告诉你如何使用 java.util.Arrays.binarySearch() method.

package gitbook.net;

import java.util.Arrays;

public class ArrayDemo {
 
   public static void main(String[] args) {

    // initializing unsorted byte array
    byte byteArr[] = {10,20,15,22,35};

    // sorting array
    Arrays.sort(byteArr);

    // let us print all the elements available in list
    System.out.println("The sorted byte array is:");
    for (byte number : byteArr) {
      System.out.println("Number = " + number);
    }

    // entering the value to be searched
    byte searchVal = 35;

    // entering the range of index
    int retVal = Arrays.binarySearch(byteArr,2,5,searchVal);

    System.out.println("The index of element 35 is : " + retVal);
  }
}

编译和执行以上程序，将得到以下的结果：

The sorted byte array is:
Number = 10
Number = 15
Number = 20
Number = 22
Number = 35
The index of element 35 is : 4

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