Java中的集合枚举()方法与示例
Java.util.Collections类的enumeration()方法用于返回对指定集合的枚举。这提供了与需要枚举作为输入的旧 API 的互操作性。
句法:
public static Enumeration enumeration(Collection c)
参数:此方法将集合c作为要为其返回枚举的参数。
返回值:此方法返回对指定集合的枚举。
以下是说明enumeration()方法的示例
示例 1:
Java
// Java program to demonstrate
// enumeration() method
// for String value
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// creating object of List
List arrlist = new ArrayList();
// Adding element to srclst
arrlist.add("Ram");
arrlist.add("Gopal");
arrlist.add("Verma");
// Print the list
System.out.println("List: " + arrlist);
// creating object of type Enumeration
Enumeration e = Collections.enumeration(arrlist);
// Print the Enumeration
System.out.println("\nEnumeration over list: ");
// print the enumeration
while (e.hasMoreElements())
System.out.println("Value is: " + e.nextElement());
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
catch (NoSuchElementException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Java
// Java program to demonstrate
// enumeration() method
// for Integer value
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// creating object of List
List arrlist = new ArrayList();
// Adding element to srclst
arrlist.add(20);
arrlist.add(30);
arrlist.add(40);
// Print the list
System.out.println("List: " + arrlist);
// creating object of type Enumeration
Enumeration e = Collections.enumeration(arrlist);
// Print the Enumeration
System.out.println("\nEnumeration over list: ");
// print the enumeration
while (e.hasMoreElements())
System.out.println("Value is: " + e.nextElement());
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
catch (NoSuchElementException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
List: [Ram, Gopal, Verma]
Enumeration over list:
Value is: Ram
Value is: Gopal
Value is: Verma
示例 2:
Java
// Java program to demonstrate
// enumeration() method
// for Integer value
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// creating object of List
List arrlist = new ArrayList();
// Adding element to srclst
arrlist.add(20);
arrlist.add(30);
arrlist.add(40);
// Print the list
System.out.println("List: " + arrlist);
// creating object of type Enumeration
Enumeration e = Collections.enumeration(arrlist);
// Print the Enumeration
System.out.println("\nEnumeration over list: ");
// print the enumeration
while (e.hasMoreElements())
System.out.println("Value is: " + e.nextElement());
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
catch (NoSuchElementException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
List: [20, 30, 40]
Enumeration over list:
Value is: 20
Value is: 30
Value is: 40