Java番石榴 | Longs.indexOf(long[] array, long target) 方法和示例

Guava 的 Longs 类的Longs.indexOf(long[] array, long target)方法接受两个参数array和target 。如果目标存在于数组中，则该方法返回其第一次出现的位置。如果数组中不存在目标，则该方法返回-1 。

句法：

public static int indexOf(long[] array, long target)

参数：该方法接受两个参数：

• 数组：这是要检查目标数组索引的整数数组。
• target：这是要作为指定数组中的元素搜索的值。

返回值：该方法返回一个整数值，如下所示：

• 如果目标存在于数组中，则返回目标第一次出现的位置。
• 否则，如果数组中不存在目标，则返回-1 。

异常：该方法不抛出任何异常。

下面的例子说明了上述方法的实现：

示例 1：

// Java code to show implementation of
// Guava's Longs.indexOf(long[] array,
// long target) method
  
import com.google.common.primitives.Longs;
import java.util.Arrays;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        // Creating an long array
        long[] arr = { 1, 2, 3, 4, 3, 5 };
  
        long target = 3;
  
        System.out.println("Array: "
                           + Arrays.toString(arr));
  
        System.out.println("Target: " + target);
  
        // Using Longs.indexOf(long[] array, long target)
        // method to get the position of the first
        // occurrence of the specified target within array,
        // or -1 if there is no such occurrence.
        int index = Longs.indexOf(arr, target);
  
        if (index != -1) {
            System.out.println("Target is present at index "
                               + index);
        }
        else {
            System.out.println("Target is not present "
                               + "in the array");
        }
    }
}

输出：

Array: [1, 2, 3, 4, 3, 5]
Target: 3
Target is present at index 2

示例 2：

// Java code to show implementation of
// Guava's Longs.indexOf(long[] array,
// long target) method
  
import com.google.common.primitives.Longs;
import java.util.Arrays;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        // Creating an long array
        long[] arr = { 3, 5, 7, 11, 13 };
  
        long target = 23;
  
        System.out.println("Array: "
                           + Arrays.toString(arr));
  
        System.out.println("Target: " + target);
  
        // Using Longs.indexOf(long[] array, long target)
        // method to get the start position of the first
        // occurrence of the specified target within array,
        // or -1 if there is no such occurrence.
        int index = Longs.indexOf(arr, target);
  
        if (index != -1) {
            System.out.println("Target is present at index "
                               + index);
        }
        else {
            System.out.println("Target is not present"
                               + " in the array");
        }
    }
}

输出：

Array: [3, 5, 7, 11, 13]
Target: 23
Target is not present in the array

参考： https://google.github.io/guava/releases/21.0/api/docs/com/google/common/primitives/Longs.html#indexOf-long:A-long-