Java 实例¶

读取输入并求和¶

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        System.out.println(a + b);
    }
}

ArrayList 排序¶

import java.util.*;

public class Main {
    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList<>(List.of(3, 1, 2));
        Collections.sort(list);
        System.out.println(list);
    }
}

HashMap 计数¶

import java.util.*;

Map<String, Integer> count = new HashMap<>();
count.put("a", count.getOrDefault("a", 0) + 1);

读取文件¶

import java.nio.file.*;

String text = Files.readString(Path.of("data.txt"));
System.out.println(text);

简单线程¶

Thread t = new Thread(() -> System.out.println("hello"));
t.start();
t.join();