在Java中设置的列表

给定一个列表（ArrayList 或 LinkedList），将其转换为Java中字符串的集合（HashSet 或 TreeSet）。

方法1（简单）
我们只需创建一个列表。我们遍历给定的集合，并将元素一个一个地添加到列表中。

// Java program to demonstrate conversion of
// list to set using simple traversal
import java.util.*;
  
class Test {
    public static void main(String[] args)
    {
  
        // Creating a list of strings
        List aList = Arrays.asList("Geeks", "for",
                     "GeeksQuiz", "GeeksforGeeks", "GFG");
  
        Set hSet = new HashSet();
        for (String x : aList)
            hSet.add(x);
  
        System.out.println("Created HashSet is");
        for (String x : hSet)
            System.out.println(x);
  
        // We can created TreeSet same way
    }
}

方法2（使用HashSet或TreeSet构造函数）

// Java program to demonstrate conversion of
// list to set using constructor
import java.util.*;
  
class Test {
    public static void main(String[] args)
    {
  
        // Creating a list of strings
        List aList = Arrays.asList("Geeks", "for",
                     "GeeksQuiz", "GeeksforGeeks", "GFG");
  
        // Creating a hash set using constructor
        Set hSet = new HashSet(aList);
  
        System.out.println("Created HashSet is");
        for (String x : hSet)
            System.out.println(x);
  
        System.out.println("Created TreeSet is");
        Set tSet = new TreeSet(aList);
        System.out.println("Created TreeSet is");
        for (String x : tSet)
            System.out.println(x);
    }
}

方法 3（使用 addAll 方法）

// Java program to demonstrate conversion of
// Set to array using addAll() method.
import java.util.*;
  
class Test {
    public static void main(String[] args)
    {
  
        // Creating a list of strings
        List aList = Arrays.asList("Geeks", "for",
                    "GeeksQuiz", "GeeksforGeeks", "GFG");
  
        Set hSet = new HashSet(aList);
        hSet.addAll(aList);
        System.out.println("Created HashSet is");
        for (String x : hSet)
            System.out.println(x);
  
        Set tSet = new TreeSet(aList);
        tSet.addAll(aList);
        System.out.println("Created TreeSet is");
        for (String x : tSet)
            System.out.println(x);
    }
}

方法4（在Java中使用流）
我们在Java中使用流将给定的列表转换为流，然后将流转换为集合。这仅适用于Java 8 或之后的版本。

// Java program to demonstrate conversion of
// Set to list using stream
import java.util.*;
import java.util.stream.*;
  
class Test {
    public static void main(String[] args)
    {
  
        // Creating a list of strings
        List aList = Arrays.asList("Geeks", "for",
                    "GeeksQuiz", "GeeksforGeeks", "GFG");
  
        // Converting to set using stream
        Set set = aList.stream().collect(Collectors.toSet());
  
        for (String x : set)
            System.out.println(x);
    }
}