Java 中的集合列表()方法，带示例
原文:https://www . geesforgeks . org/collections-list-method-in-Java-with-examples/
java.util.Collections 类的 list() 方法用于返回一个数组列表，该数组列表包含指定枚举返回的元素，这些元素按照枚举返回的顺序排列。该方法提供了返回枚举的旧 API 和需要集合的新 API 之间的互操作性。
语法:
public static ArrayList list(Enumeration e)
参数:该方法以枚举 e 为参数，为返回的数组列表提供元素。
返回值:这个方法返回一个数组列表，包含指定枚举返回的元素。
以下是举例说明列表()方法
例 1:
// Java program to demonstrate
// list() method
// for String value
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// creating object of List<String>
List<String> arrlist = new ArrayList<String>();
// creating object of Vector<String>
Vector<String> v = new Vector<String>();
// Adding element to Vector v
v.add("A");
v.add("B");
v.add("C");
v.add("D");
v.add("E");
// printing the list
System.out.println("Current list : " + arrlist);
// creating Enumeration
Enumeration<String> e = v.elements();
// getting arrlist of specified Enumeration
// using list() method
arrlist = Collections.list(e);
// printing the arrlist
System.out.println("Returned list: " + arrlist);
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
Current list : []
Returned list: [A, B, C, D, E]
例 2:
// Java program to demonstrate
// list() method
// for Integer value
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// creating object of List<String>
List<Integer> arrlist = new ArrayList<Integer>();
// creating object of Vector<String>
Vector<Integer> v = new Vector<Integer>();
// Adding element to Vector v
v.add(10);
v.add(20);
v.add(30);
v.add(40);
v.add(50);
// printing the list
System.out.println("Current list : " + arrlist);
// creating Enumeration
Enumeration<Integer> e = v.elements();
// getting arrlist of specified Enumeration
// using list() method
arrlist = Collections.list(e);
// printing the arrlist
System.out.println("Returned list: "
+ arrlist);
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
Current list : []
Returned list: [10, 20, 30, 40, 50]
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