Java 中要设置的列表
给定一个列表(数组列表或链接列表，将其转换为 Java 中字符串的集合 ( HashSet 或 TreeSet )。
方法 1(简单) 我们简单地创建一个列表。我们遍历给定的集合，一个接一个地向列表中添加元素。
// 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<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
Set<String> hSet = new HashSet<String>();
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<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
// Creating a hash set using constructor
Set<String> hSet = new HashSet<String>(aList);
System.out.println("Created HashSet is");
for (String x : hSet)
System.out.println(x);
System.out.println("Created TreeSet is");
Set<String> tSet = new TreeSet<String>(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<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
Set<String> hSet = new HashSet<String>(aList);
hSet.addAll(aList);
System.out.println("Created HashSet is");
for (String x : hSet)
System.out.println(x);
Set<String> tSet = new TreeSet<String>(aList);
tSet.addAll(aList);
System.out.println("Created TreeSet is");
for (String x : tSet)
System.out.println(x);
}
}
方法 4(使用 Java 中的流 ) 我们使用 Java 中的流将给定列表转换为流，然后流进行设置。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<String> aList = Arrays.asList("Geeks", "for",
"GeeksQuiz", "GeeksforGeeks", "GFG");
// Converting to set using stream
Set<String> set = aList.stream().collect(Collectors.toSet());
for (String x : set)
System.out.println(x);
}
}
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