Java ACM 模式

Java ACM 模式

输入

一维数据 Scanner

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String s = sc.next();
		double d = sc.nextDouble();
	}
}

二维数据 BufferedReader

注意导入包和抛出异常

import java.util.*;
import java.io.*;

public class Main {
	static class Reader {
	    static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
	    static StringTokenizer tokenizer = new StringTokenizer("");
	
	    static String nextLine() throws IOException{// 读取下一行字符串
	        return reader.readLine();
	    }
	
	    static String next() throws IOException {// 读取下一个字符串
	        while (!tokenizer.hasMoreTokens()) {
	            tokenizer = new StringTokenizer(nextLine());
	        }
	        return tokenizer.nextToken();
	    }
	
	    static int nextInt() throws IOException {// 读取下一个int型数值
	        return Integer.parseInt(next());
	    }
	
	    static double nextDouble() throws IOException {// 读取下一个double型数值
	        return Double.parseDouble(next());
	    }
	}
}

使用例 1：readLine()​ 之后使用 split()​ 分割，不需要手搓工具类

public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n, m;
    n = Integer.parseInt(input[0]);
    m = Integer.parseInt(input[1]);

    input = br.readLine().split(" ");
    for (int i = 1; i <= n; i++) {
        r[i] = Long.parseLong(input[i - 1]);
    }

    for (int i = 1; i <= m; i++) {
        input = br.readLine().split(" ");
        d[i] = Integer.parseInt(input[0]);
        s[i] = Integer.parseInt(input[1]);
        t[i] = Integer.parseInt(input[2]);
    }
}

使用例 2：单独读取每个数据，需要手搓完整的工具类，用法和 Scanner​ 保持一致，需要避免 next()​ 和 nextLine()​ 混用

import java.util.*;
import java.io.*;

public class Main {
	public static void main(String[] args) throw Exception {
		int n = Reader.nextInt();
		double d = Reader.nextDouble();
		// 如果需要long类型手动加即可
		String s = Reader.next();
	}

	static class Reader {
	    static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
	    static StringTokenizer tokenizer = new StringTokenizer("");
	
	    static String nextLine() throws IOException{// 读取下一行字符串
	        return reader.readLine();
	    }
	
	    static String next() throws IOException {// 读取下一个字符串
	        while (!tokenizer.hasMoreTokens()) {
	            tokenizer = new StringTokenizer(nextLine());
	        }
	        return tokenizer.nextToken();
	    }
	
	    static int nextInt() throws IOException {// 读取下一个int型数值
	        return Integer.parseInt(next());
	    }
	
	    static double nextDouble() throws IOException {// 读取下一个double型数值
	        return Double.parseDouble(next());
	    }
	}
}

输出

一维数据 System.out

public static void main(String[] args) throws Exception {
	System.out.println();
}

二维数据 BufferedWriter

• ​write()​ 不带\n，注意传入数字时要转换为字符串
• 最后一定要使用 flush() ​清空缓冲区，否则会有不输出的情况（都存在缓冲区里）
• close() ​加不加随意

import java.util.*;
import java.io.*;

public class Main {
	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
	
	public static void main(String[] args) throws Exception {
		bw.write();
		bw.write("\n");
		// 清空缓冲区
		bw.flush();
		bw.close();
	}
}