我必须记下文件“ test.txt”中有多少个字母（字符）。我记下来了，但它也包括空格，我不想包括在内。有什么建议吗？非常感谢。
import java.io.*;
class EnglishAnalysis
{
public static void main(String[] args)
{
try
{
FileReader fr = new FileReader("test.txt");
BufferedReader br = new BufferedReader(fr);
int count = 0;
String lineCharacters [];
String line;
line = br.readLine();
while (line != null)
{
lineCharacters = line.split("");
for (int i = 0; i < lineCharacters.length; i++)
{
count ++;
line = br.readLine();
}
System.out.println(count);
}
br.close();
}
catch (IOException e) {}
}
}
答案 0 :(得分：2)
或者（对于Java 8+），您可以使用lines()和chars()方法很容易地做到这一点：
BufferedReader br = new BufferedReader(fr);
long count = br.lines().flatMapToInt(e -> e.codePoints()).filter(e -> !Character.isWhiteSpace(e)).count();
将提取文件行中的Stream<String>，使用String::codePoints将其平面映射到字符，过滤出所有空白，然后计算元素
答案 1 :(得分：1)
也许我错过了一些东西，但我不知道拆分有什么好处。我会这样做：
public static void main(String[] args) {
try {
FileReader fr = new FileReader("/tmp/test.txt");
BufferedReader br = new BufferedReader(fr);
int count = 0;
String line;
line = br.readLine();
while (line != null) {
for (int i = 0; i < line.length(); i++)
if (!Character.isWhitespace(line.charAt(i)))
count++;
line = br.readLine();
}
br.close();
System.out.println(count);
} catch (IOException ex) {
System.out.println(ex);
}
}
特别是，我认为根本不需要通过调用split，制作额外的副本，执行查找/替换等操作来修改输入。这一切都需要花费额外的时间和空间。
实际上，我看不出任何理由来烦扰文件的处理：
public static void main(String[] args) {
try {
FileReader fr = new FileReader("/tmp/test.txt");
BufferedReader br = new BufferedReader(fr);
int count = 0;
while (true) {
int c = br.read();
if (c < 0)
break;
if (!Character.isWhitespace(c))
count++;
}
br.close();
System.out.println(count);
} catch (IOException ex) {
System.out.println(ex);
}
}
本身使用BufferedReader可以提高不逐字符读取文件的效率。因此，您可以通过这种方式保存每行的额外副本。
答案 2 :(得分：1)
为什么从所有空格中清除每行后就不添加字符数：
while (line != null) {
count += line.replaceAll("\\s+", "").length();
line = br.readLine();
}
答案 3 :(得分：0)
为什么在进行分割和计数之前不从字符串中删除空格？
使用正则表达式的一种实现方式：
while (line != null)
{
line.replaceAll("\\s+","");
lineCharacters = line.split("");
...
}
答案 4 :(得分：0)
角色类具有“ isWhiteSpace（）”方法
java.lang.Character.isWhitespace（char ch）
(venv) localhost:mainsite_project davea$ python manage.py migrate mainsite
Operations to perform:
Apply all migrations: mainsite
Running migrations:
Applying mainsite.0019_auto_20190401_2139...Traceback (most recent call last):
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/models/options.py", line 564, in get_field
return self.fields_map[field_name]
KeyError: 'website'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "manage.py", line 22, in <module>
execute_from_command_line(sys.argv)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
utility.execute()
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/core/management/base.py", line 316, in run_from_argv
self.execute(*args, **cmd_options)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/core/management/base.py", line 353, in execute
output = self.handle(*args, **options)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/core/management/base.py", line 83, in wrapped
res = handle_func(*args, **kwargs)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/core/management/commands/migrate.py", line 203, in handle
fake_initial=fake_initial,
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/migrations/executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/migrations/migration.py", line 124, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/migrations/operations/models.py", line 514, in database_forwards
getattr(new_model._meta, self.option_name, set()),
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 356, in alter_unique_together
self._delete_composed_index(model, fields, {'unique': True}, self.sql_delete_unique)
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 379, in _delete_composed_index
columns = [model._meta.get_field(field).column for field in fields]
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 379, in <listcomp>
columns = [model._meta.get_field(field).column for field in fields]
File "/Users/davea/Documents/workspace/mainsite_project/venv/lib/python3.7/site-packages/django/db/models/options.py", line 566, in get_field
raise FieldDoesNotExist("%s has no field named '%s'" % (self.object_name, field_name))
django.core.exceptions.FieldDoesNotExist: MainSiteStatByHour has no field named 'website'