Java程序从TreeSet获取耳机
要从TreeSet获取HeadSet，首先创建一个TreeSet并添加一些元素：
TreeSet<String> treeSet = new TreeSet<String>();
treeSet.add("ABC");
treeSet.add("DEF");
treeSet.add("GHI");
treeSet.add("JKL");
treeSet.add("MNO");
treeSet.add("PQR");要获取耳机，请使用以下headset()方法：
SortedSet<String> set = treeSet.headSet("MNO");
System.out.println("Head Set = " + set);您还可以像这样更改值：
set = treeSet.headSet("GHI");
System.out.println("Head Set = " + set);示例
import java.util.SortedSet;
import java.util.TreeSet;
public class Demo {
public static void main(String[] args) {
TreeSet<String> treeSet = new TreeSet<String>();
treeSet.add("ABC");
treeSet.add("DEF");
treeSet.add("GHI");
treeSet.add("JKL");
treeSet.add("MNO");
treeSet.add("PQR");
SortedSet<String> set = treeSet.headSet("MNO");
System.out.println("Head Set = " + set);
set = treeSet.headSet("GHI");
System.out.println("Head Set = " + set);
set = treeSet.headSet("ABC");
System.out.println("Head Set = " + set);
}
}输出结果
Head Set = [ABC, DEF, GHI, JKL] Head Set = [ABC, DEF] Head Set = []