java 读取txt文件，一列日期(8位，如20160524)，一列数值，将相同日期的数值求和并打印

Question

求前辈帮忙写下

Answer 1

public static void 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;
Integer v = map.get(str);
v = v == null ? 1 : v.intValue() + 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();
}
}
}
}