Guava – Longs.indexOf方法及实例

Guava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，该方法返回其第一次出现的起始位置。如果目标在数组中不存在，该方法返回-1。

语法：

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

参数： 该方法接受两个参数。

• array：是一个整数数组，目标数组将在其中检查索引。
• target: 作为指定数组的一个子序列，要搜索的数组。

返回值： 该方法返回一个整数值，如下所示。

• 如果目标数组在数组中存在，它返回目标数组第一次出现的起始位置。
• 否则，如果目标在数组中不存在，则返回-1。

异常情况： 该方法没有抛出任何异常。

下面的例子说明了上述方法的实现。

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, 4, 3 };
  
        System.out.println("Array: "
                           + Arrays.toString(arr));
  
        System.out.println("Target Array: "
                           + Arrays.toString(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: [1, 2, 3, 4, 3, 5]
Target Array: [3, 4, 3]
Target is present at index 2

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, 37 };
  
        System.out.println("Array: "
                           + Arrays.toString(arr));
  
        System.out.println("Target Array: "
                           + Arrays.toString(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 Array: [23, 37]
Target is not present in the array

参考资料:

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