java toarray

向量類toArray()方法 (Vector Class toArray() method)

Syntax:

句法：

    public Object[] toArray();
public Object[] toArray(Type[] ty);

• toArray() method is available in java.util package.

  toArray()方法在java.util包中可用。

• toArray() method is used to return an array of elements that exists in this Vector.

  toArray()方法用于返回此Vector中存在的元素的數組。

• toArray(Type[] ty) method is used to return an array that holds all the existing elements in this vector.

  toArray(Type [] ty)方法用于返回一個數組，該數組包含此向量中的所有現有元素。

• These methods may throw an exception at the time of representing an array.

  這些方法在表示數組時可能會引發異常。

  • ArrayStoreException: This exception may throw when the given parameter is not in a range.ArrayStoreException ：如果給定參數不在范圍內，則可能引發此異常。
  • NullPointerException: This exception may throw when the given parameter is null exists.NullPointerException ：當給定參數為null時，可能引發此異常。

• These are non-static methods and it is accessible with class objects and if we try to access these methods with the class name then we will get an error.

  這些是非靜態方法，可通過類對象訪問，如果嘗試使用類名訪問這些方法，則會收到錯誤消息。

Parameter(s):

參數：

• In the first case, toArray()

  在第一種情況下， toArray()

  • It does not accept any parameters.

• In the first case, toArray(Type[] ty)

  在第一種情況下， toArray(Type [] ty)

  • Type[] ty – represents the array where we have to store all existing elements of this Vector.
  • Type [] ty –表示我們必須存儲此Vector所有現有元素的數組。

Return value:

返回值：

In the first case, the return type of the method is Object [] – It returns an object array (Object []) that hold all elements exists in this vector.

在第一種情況下，該方法的返回類型為Object [] –它返回一個對象數組(Object [])，該數組保存此向量中存在的所有元素。

In the second case, the return type of the method is Type [] – It returns an array of same type that holds vector elements.

在第二種情況下，該方法的返回類型為Type [] –它返回一個包含向量元素的相同類型的數組。

Example:

例：

// Java program to demonstrate the example 
// of toArray() method of Vector
import java.util.*;
public class ToArrayOfVector {
public static void main(String[] args) {
// Instantiates a vector object  
String[] s = {};
Vector < String > v = new Vector < String > (Arrays.asList(s));
String[] str = new String[5];
// By using add() method is to add
// the elements in vector
v.add("C");
v.add("C++");
v.add("SFDC");
v.add("JAVA");
//Display Vector
System.out.println("v: " + v);
// By using toArray() method is to
// return an array that contains all the 
// vector elements
str = v.toArray(str);
System.out.println("v.toArray(): ");
for (int i = 0; i < str.length; ++i)
System.out.println(str[i]);
// By using toArray(array) method is to
// return an array that contains all the 
// vector elements by using an array
v.toArray(str);
System.out.println("v.toArray(str): ");
for (int i = 0; i < str.length; ++i)
System.out.println(str[i]);
}
}

Output

輸出量

v: [C, C++, SFDC, JAVA]
v.toArray(): 
C
C++
SFDC
JAVA
null
v.toArray(str): 
C
C++
SFDC
JAVA
null

翻譯自: https://www.includehelp.com/java/vector-toarray-method-with-example.aspx

java toarray