Ints toArray()函数|番石榴| Java
原文:https://www . geesforgeks . org/ints-to array-function-guava-Java/
番石榴的T1Ints。toArray() 返回一个包含集合中每个值的数组，以 Number.intValue() 的方式转换为 int 值
语法:
public static int[]
toArray(Collection<? extends Number> collection)
参数:该方法以集合为参数，该参数是号实例的集合。
返回值:这个方法返回一个数组，包含与集合相同的值，顺序相同，转换为原语。
异常:如果集合或其任何元素为空，该方法将抛出 空指针异常 。
以下示例说明了 Ints.toArray()方法:
例 1:
// Java code to show implementation of
// Guava's Ints.toArray() method
import com.google.common.primitives.Ints;
import java.util.Arrays;
import java.util.List;
class GFG {
// Driver's code
public static void main(String[] args)
{
// Creating a List of Integers
List<Integer>
myList = Arrays.asList(1, 2, 3, 4, 5);
// Using Ints.toArray() method to convert
// a List or Set of Integer to an array
// of Int
int[] arr = Ints.toArray(myList);
// Displaying an array containing each
// value of collection,
// converted to a int value
System.out.println("Array from given List: "
+ Arrays.toString(arr));
}
}
输出:
Array from given List: [1, 2, 3, 4, 5]
示例 2: 演示 NullPointerException
// Java code to show implementation of
// Guava's Ints.toArray() method
import com.google.common.primitives.Ints;
import java.util.Arrays;
import java.util.List;
class GFG {
// Driver's code
public static void main(String[] args)
{
try {
// Creating a List of Integers
List<Integer>
myList = Arrays.asList(2, 4, null);
// Using Ints.toArray() method to convert
// a List or Set of Integer to an array
// of Int. This should raise "NullPointerException"
// as the collection contains "null" as an element
int[] arr = Ints.toArray(myList);
// Displaying an array containing each
// value of collection, converted to a int value
System.out.println(Arrays.toString(arr));
}
catch (Exception e) {
System.out.println("Exception: " + e);
}
}
}
输出:
Exception: java.lang.NullPointerException
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