java 求帮写一个关于读文件内容并计算打印的小程序

Question

一列日，一列数值
要求如图，希望有空的前辈能花点时间帮忙写一下，非常感激！

需要再增加一个功能，输入日期，就能显示对应日期的数字总合

Answer 1

public static Map<String, Integer< countDate(String filePath) {
Map<String, Integer< map = new HashMap<String, Integer<();
FileInputStream in = null;
try {
//filepath为文件路径
in = new FileInputStream(filePath);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
while(true) {
//按行读取
String str = br.readLine();
if (str == null) break;
if ((str = str.trim()).length() == 0) continue;
str = str.replaceAll("\s+", " ");
String[] result = str.split(" ");
Integer v = map.get(result[0]);
v = v == null ? Integer.valueOf(result[1]) : v.intValue() + Integer.parseInt(result[1]);
map.put(str, v);
}
Iterator<String> iterator = map.keySet().iterator();
while(iterator.hasNext()) {
String key = iterator.next();
System.out.println("date="+key+",totalCount="+map.get(key));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (in != null) {
try {
in.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
return map;
}

public static void read(String filePath) {
    Map<String, Integer<  map = countDate(filePath);
    System.out.print("请输入日期:");
    Scanner in = new Scanner(System.in);
    try {
        String date = in.nextLine();
        Integer count = map.get(date);
        int c = count == null ? 0 : count.intValue();
        System.out.println("该日期下的总数为:" + c);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

    把第一个方法改为有返回值的，然后main调用第二个方法就可以