Java 中的 PriorityQueue toArray()方法
原文:https://www . geesforgeks . org/priorityqueue-to array-method-in-Java/
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The java.util.PriorityQueue.toArray() method in Java is used to form an array of the same elements as that of the Priority Queue. Basically, it copies all the element from a priority queue to a new array.
语法:
java Object[] arr = Priority_Queue.toArray()参数:该方法不取任何参数。
返回值:该方法返回一个数组，该数组包含类似于优先级队列的元素。
下面的程序说明了 Java . util . priorityqueue . toarray()方法。 节目一:
```java // Java code to illustrate toArray() import java.util.*;
public class PriorityQueueDemo { public static void main(String args[]) { // Creating an empty PriorityQueue PriorityQueue queue = new PriorityQueue();
// Use add() method to add elements into the Queue queue.add("Welcome"); queue.add("To"); queue.add("Geeks"); queue.add("For"); queue.add("Geeks");
// Displaying the PriorityQueue System.out.println("The PriorityQueue: " + queue);
// Creating the array and using toArray() Object[] arr = queue.toArray();
System.out.println("The array is:"); for (int j = 0; j < arr.length; j++) System.out.println(arr[j]); } } ```
Output:
```java The PriorityQueue: [For, Geeks, To, Welcome, Geeks] The array is: For Geeks To Welcome Geeks
```
程序 2:
```java // Java code to illustrate toArray() import java.util.*;
public class PriorityQueueDemo { public static void main(String args[]) { // Creating an empty PriorityQueue PriorityQueue queue = new PriorityQueue();
// Use add() method to add elements into the Queue queue.add(10); queue.add(15); queue.add(30); queue.add(20); queue.add(5); queue.add(25);
// Displaying the PriorityQueue System.out.println("The PriorityQueue: " + queue);
// Creating the array and using toArray() Object[] arr = queue.toArray();
System.out.println("The array is:"); for (int j = 0; j < arr.length; j++) System.out.println(arr[j]); } } ```
Output:
```java The PriorityQueue: [5, 10, 25, 20, 15, 30] The array is: 5 10 25 20 15 30
```
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The java.util.PriorityQueue.toArray(arr[]) method in Java is used to form an array of the same elements as that of the Priority Queue. Basically, it copies all the element from a priority queue to a new array. It creates multiple arrays, unlike the previous method without parameters. This method copies all of the elements into the arr[]. Syntax:
java Object[] arr1 = Priority_Queue.toArray(arr[])参数:该方法接受一个参数 arr[] ，队列的所有元素都将被复制到该参数中。
返回值:该方法返回一个数组，该数组包含类似于优先级队列的元素。
Exception:
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ArrayStoreException:当提到的数组属于不同的类型，并且不能与队列中提到的元素进行比较时。
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NullPointerException: If the array is Null, then this exception is thrown.
下面的程序说明了 Java . util . priorityqueue . to array(arr[])方法的工作原理。
```java // Java code to illustrate toArray(arr[]) import java.util.*;
public class PriorityQueueDemo { public static void main(String args[]) { // Creating an empty PriorityQueue PriorityQueue queue = new PriorityQueue();
// Use add() method to add elements into the Queue queue.add("Welcome"); queue.add("To"); queue.add("Geeks"); queue.add("For"); queue.add("Geeks");
// Displaying the PriorityQueue System.out.println("The PriorityQueue: " + queue);
// Creating the array and using toArray() String[] arr = new String[5]; String[] arr1 = queue.toArray(arr);
// Displaying arr System.out.println("The arr[] is:"); for (int j = 0; j < arr.length; j++) System.out.println(arr[j]);
// Displaying arr1 System.out.println(); System.out.println("The arr1[] is:"); for (int i = 0; i < arr1.length; i++) System.out.println(arr1[i]); } } ```
Output:
```java The PriorityQueue: [For, Geeks, To, Welcome, Geeks] The arr[] is: For Geeks To Welcome Geeks
The arr1[] is: For Geeks To Welcome Geeks
```
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