Guava – Chars.toArray()方法与实例

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Guava Chars.toArray() 方法与实例

Guava库中Chars类的toArray()方法用于将作为参数传递给该方法的char值转换成Char数组。这些char值被作为一个集合传递给这个方法。该方法返回一个Char数组.

语法:

public static char[] toArray(Collection collection)

参数: 这个方法接受一个强制参数collection,它是要转换为char数组的char值的集合。

返回值: 该方法返回一个char数组,包含与collection相同的值,顺序相同。

异常情况: 如果传递的集合或其任何元素为空,该方法会抛出NullPointerException。

以下程序说明了toArray()方法的使用。

例子 1 :

// Java code to show implementation of// Guava's Chars.toArray() method  import com.google.common.primitives.Chars;import java.util.Arrays;import java.util.List;  class GFG {      // Driver's code    public static void main(String[] args)    {          // Creating a List of Chars        List<Character> myList            = Arrays.asList('G', 'E', 'E', 'K', 'S');          // Using Chars.toArray() method to convert        // a List or Set of Char to an array of Char        char[] arr = Chars.toArray(myList);          // Displaying an array containing each        // value of collection,        // converted to a char value        System.out.println(Arrays.toString(arr));    }}

输出:

[G, E, E, K, S]

例子 2 :

// Java code to show implementation of// Guava's Chars.toArray() method  import com.google.common.primitives.Chars;import java.util.Arrays;import java.util.List;  class GFG {      // Driver's code    public static void main(String[] args)    {          try {            // Creating a List of Chars            List<Character> myList                = Arrays.asList('a', 'b', null);              // Using Chars.toArray() method            // to convert a List or Set of Char            // to an array of Char.            // This should raise "NullPointerException"            // as the collection contains "null"            // as an element            char[] arr = Chars.toArray(myList);              // Displaying an array containing each            // value of collection,            // converted to a char value            System.out.println(Arrays                                   .toString(arr));        }        catch (Exception e) {            System.out.println(e);        }    }}

输出:

java.lang.NullPointerException

参考资料 :
https://google.github.io/guava/releases/18.0/api/docs/com/google/common/primitives/Chars.html#toArray(java.util.Collection)

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