在 Java 中设置为列表
给定 Java 中字符串的集合 ( HashSet 或 TreeSet )，将其转换为字符串的列表(数组列表或链接列表)。
Input : Set hash_Set = new HashSet();
hash_Set.add("Geeks");
hash_Set.add("For");
Output : ArrayList or Linked List with
following content
{"Geeks", "for"}
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
// Set to array using simple traversal
import java.util.*;
class Test {
public static void main(String[] args) {
// Creating a hash set of strings
Set<String> s = new HashSet<String>();
s.add("Geeks");
s.add("for");
int n = s.size();
List<String> aList = new ArrayList<String>(n);
for (String x : s)
aList.add(x);
System.out.println("Created ArrayList is");
for (String x : aList)
System.out.println(x);
// We can created LinkedList same way
}
}
Output:
Created ArrayList is
Geeks
for
方法 2(使用数组列表或链接列表构造函数)
// Java program to demonstrate conversion of
// Set to list using constructor
import java.util.*;
class Test {
public static void main(String[] args) {
// Creating a hash set of strings
Set<String> s = new HashSet<String>();
s.add("Geeks");
s.add("for");
// Creating an array list using constructor
List<String> aList = new ArrayList<String>(s);
System.out.println("Created ArrayList is");
for (String x : aList)
System.out.println(x);
System.out.println("Created LinkedList is");
List<String> lList = new LinkedList<String>(s);
for (String x : lList)
System.out.println(x);
}
}
Output:
Created ArrayList is
Geeks
for
Created LinkedList is
Geeks
for
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 hash set of strings
Set<String> s = new HashSet<String>();
s.add("Geeks");
s.add("for");
List<String> aList = new ArrayList<String>();
aList.addAll(s);
System.out.println("Created ArrayList is");
for (String x : aList)
System.out.println(x);
List<String> lList = new LinkedList<String>();
lList.addAll(s);
System.out.println("Created LinkedList is");
for (String x : lList)
System.out.println(x);
}
}
Output:
Created ArrayList is
Geeks
for
Created LinkedList is
Geeks
for
方法 4(使用 Java 中的流 ) 我们使用 Java 中的流将给定集合转换为蒸汽，然后流至列表。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 hash set of strings
Set<String> s = new HashSet<String>();
s.add("Geeks");
s.add("for");
List<String> aList = s.stream().collect(Collectors.toList());
for (String x : aList)
System.out.println(x);
}
}
Output:
Geeks
for
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