Java 中 LinkedBlockingQueue toArray()方法
原文:https://www . geeksforgeeks . org/linkedblockingqueue-to array-method-in-Java/
toarray()
LinkedBlockingQueue 的 toArray 方法用于创建一个数组，该数组具有与该 LinkedBlockingQueue 相同的元素，并按适当的顺序排列。实际上，这个方法将 LinkedBlockingQueue 中的所有元素复制到一个新数组中。此方法充当数组和 LinkedBlockingQueue 之间的桥梁。
语法:
public Object[] toArray()
返回值:这个方法返回一个包含 LinkedBlockingQueue 元素的数组。
下面的程序说明了 LinkedBlockingQueue 类的 toArray()方法:
程序 1:
Java
// Java Program Demonstrate toArray()
// method of LinkedBlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public static void main(String[] args)
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 50;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<Integer> linkedQueue
= new LinkedBlockingQueue<Integer>(capacityOfQueue);
// Add element to LinkedBlockingQueue
linkedQueue.add(2300);
linkedQueue.add(1322);
linkedQueue.add(8945);
linkedQueue.add(6512);
// print linkedQueue details
System.out.println("Queue Contains "
+ linkedQueue);
// apply toArray() method on linkedQueue
Object[] array = linkedQueue.toArray();
// Print elements of array
System.out.println("The array contains:");
for (Object i : array) {
System.out.print(i + "\t");
}
}
}
输出:
Queue Contains [2300, 1322, 8945, 6512]
The array contains:
2300 1322 8945 6512
程序二:
Java
// Java Program Demonstrate toArray()
// method of LinkedBlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public static void main(String[] args)
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 5;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<String> linkedQueue
= new LinkedBlockingQueue<String>(capacityOfQueue);
// Add 5 elements to ArrayBlockingQueue
linkedQueue.offer("User");
linkedQueue.offer("Employee");
linkedQueue.offer("Manager");
linkedQueue.offer("Analyst");
linkedQueue.offer("HR");
// apply toArray() method on linkedQueue
Object[] array = linkedQueue.toArray();
// Print elements of array
System.out.println("The array contains:");
for (Object i : array) {
System.out.print(i + " ");
}
}
}
输出:
The array contains:
User Employee Manager Analyst HR
toaarray(t[]a)
LinkedBlockingQueue 的 toArray(T[] a)方法用于以适当的顺序返回一个数组，该数组包含与该 LinkedBlockingQueue 相同的元素。此方法与 toArray()的区别仅在于一个条件。如果 LinkedBlockingQueue 的大小小于或等于传递的数组，则返回的数组的类型与参数中传递的数组相同。否则，将分配一个与指定数组类型相同的新数组，并且该数组的大小等于该队列的大小。此方法充当数组和集合之间的桥梁。
语法:
public <T> T[] toArray(T[] a)
参数:该方法以一个数组为参数，如果队列足够大，队列的所有元素都将被复制到该数组中。否则，会为此分配一个相同运行时类型的新数组。
返回值:这个方法返回一个包含这个队列中所有元素的数组。
异常当传递的数组与 LinkedBlockingQueue 的元素类型不同时，该方法抛出以下异常:
- array storeexception:。
- Null pointer exception: If the passed array is empty.
下面的程序说明了 LinkedBlockingQueue 类的数组方法:
程序 1
Java
// Java program to demonstrate
// toArray(T[] a) method
// method of LinkedBlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public static void main(String[] args)
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 10;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<String> linkedQueue
= new LinkedBlockingQueue<String>(capacityOfQueue);
// Add 5 elements to ArrayBlockingQueue
linkedQueue.offer("Sonali");
linkedQueue.offer("Sonam");
linkedQueue.offer("Kajal");
linkedQueue.offer("Komal");
// Print queue
System.out.println("Queue Contains : " + linkedQueue);
// the array to pass in toArray()
// array has size equal to size of linkedQueue
String[] passArray = new String[linkedQueue.size()];
// Calling toArray(T[] a) method
Object[] array = linkedQueue.toArray(passArray);
// Print elements of passed array
System.out.println("\nThe array passed :");
for (Object i : passArray) {
System.out.print(i + "\t");
}
System.out.println();
// Print elements of returned array
System.out.println("\nThe array returned :");
for (Object i : array) {
System.out.print(i + "\t");
}
}
}
输出
Queue Contains : [Sonali, Sonam, Kajal, Komal]
The array passed :
Sonali Sonam Kajal Komal
The array returned :
Sonali Sonam Kajal Komal
程序 2: 在 toArray()中传递不同于 LinkedBlockingQueue 包含的元素类型的数组。toArray()方法将因此引发异常 ArrayStoreException。
Java
// Java Program Demonstrate
// toArray()
// method Exceptions.
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 4;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<Integer>
linkedQueue = new LinkedBlockingQueue<Integer>(capacityOfQueue);
// add elements to queue
linkedQueue.put(46541);
linkedQueue.put(44648);
linkedQueue.put(45654);
// create a array of Strings
String[] arr = {};
// apply toArray method and Pass array of String
// as parameter to toArray method
try {
// LinkedBlockingQueue has type Integer but we are passing
// String Type array so toArray method will throw
// Exception
String[] array = linkedQueue.toArray(arr);
// print elements of queue
System.out.println("Items in Queue are " + array);
}
catch (Exception e) {
System.out.println("Exception: " + e);
}
}
}
输出:
Exception: java.lang.ArrayStoreException: java.lang.Integer
程序 3: 在数组()中传递空数组。因此 toArray()方法将引发 NullPointerException。
Java
// Java program to demonstrate
// toArray() method Exceptions.
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 4;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<String>
linkedQueue = new LinkedBlockingQueue<String>(capacityOfQueue);
// add elements to queue
linkedQueue.put("aman");
linkedQueue.put("khan");
linkedQueue.put("Prakash");
// create a array of Strings
String[] arr = null;
// apply toArray method and Pass array of String
// as parameter to toArray method
try {
/// we are passing array with null values
String[] array = linkedQueue.toArray(arr);
// print elements of queue
System.out.println("Items in Queue are " + array);
}
catch (Exception e) {
System.out.println("Exception: " + e);
}
}
}
输出:
Exception: java.lang.NullPointerException
参考:
- https://docs。甲骨文。com/javase/8/docs/API/Java/util/concurrent/linkedblockingqueue。html # to array–
- https://docs。甲骨文。com/javase/8/docs/API/Java/util/concurrent/linkedblockingqueue。html # to array-T:A-
版权属于：月萌API www.moonapi.com，转载请注明出处
