我很好奇是否有人可以帮助我理解我做错了什么。我只是在学习如何在 Java 中使用 OutputStreams 和 BufferedWriters，但我不确定我做得对。我知道如何使用一个 OutputStream 和 BufferedWriter，但我的问题是试图在一个类中使用它们中的两个。
现在我得到的主要错误在于我的 LowerAndUpper 类，并且在我的 try/catch 语句和 if/else 语句之间，我不确定我做错了什么。因此，我很感谢你们在这件事上提供的任何帮助，并帮助我了解如何同时使用其中两个项目。
这些是我遇到的错误，由于我还是 Java 的初学者，所以我并不完全理解这里发生了什么：
第 40 行错误：')' 如果 (creditsEarned>60 writerUpper.write){
第 40 行错误：不是语句 if (creditsEarned>60 writerUpper.write){
第 40 行错误：';' 预期如果（creditsEarned>60 writerUpper.write）{
第 43 行错误：没有 'if' 的 'else' else (writerLower.write){
第 43 行错误：不是其他语句（writerLower.write）{
第 43 行错误：';' 其他预期（writerLower.write）{
这是我的代码：
import java.nio.file.*;
import java.io.*;
import static java.nio.file.StandardOpenOption.*;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.attribute.FileTime;
import java.util.InputMismatchException;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class LowerAndUpper {
public static void main(String[] args) {
Path file1 =
Paths.get("C:/temp/lowerclassman.txt");
Path file2 =
Paths.get("C:/temp/upperclassman.txt");
String s = "";
String delimiter = ",";
int id;
String name;
double creditsEarned;
final int QUIT = 999;
try {
OutputStream output = new BufferedOutputStream(Files.newOutputStream(file1));
BufferedWriter writerUpper = new BufferedWriter(new OutputStreamWriter(output));
OutputStream output2 = new BufferedOutputStream(Files.newOutputStream(file2));
BufferedWriter writerLower = new BufferedWriter(new OutputStreamWriter(output2));
while (true) {
id = Validate.collectInt("Enter student ID number or " + QUIT
+ " to quit >> ");
if (id == QUIT) {
break;
}
name = Validate.collectString(2, "Enter student name "
+ id + " >> ");
creditsEarned = Validate.collectWage("Enter credit hours >> ");
s = id + delimiter + name + delimiter + creditsEarned;
if (creditsEarned>60 writerUpper.write){
System.out.println("Student is a Lowerclassman");
else (writerLower.write){
System.out.println("Student is an Upperclassman");
}
}
writerUpper.write(s, 0, s.length());
r.newLine();
} //end while
writer.close();
writer2.close();
} catch (Exception e) {
System.out.println("Message: " + e);
}
}
}
// **************************************************************************
class Validate {
public static int collectInt(String messageIn) {
Scanner input = new Scanner(System.in);
int intOut = 0;
boolean valid = true;
System.out.println(messageIn);
while (valid) {
try {
intOut = input.nextInt();
valid = false;
} catch (InputMismatchException ie) {
input.nextLine();
System.out.println("You must enter a whole number");
} //end catch
} //end while
return intOut;
}//end collectInt method
//*************************************************************************
public static String collectString(int strLen, String messageIn) {
Scanner input = new Scanner(System.in);
String strOut = "";
boolean valid = true;
System.out.println(messageIn);
while (valid) {
try {
strOut = input.nextLine();
if (strOut.length() < strLen) {
throw new Exception();
}
valid = false;
} catch (Exception e) {
System.out.printf("You must be at least %s characters\n",
strLen);
} //end catch
} //end while
return strOut;
} //end collectString method
//*************************************************************************
public static String collectZipcode(String messageIn) {
Scanner input = new Scanner(System.in);
String strOut = "";
boolean valid = true;
System.out.println(messageIn);
while (valid) {
try {
strOut = input.nextLine();
Integer.parseInt(strOut);
if (strOut.length() != 5) {
throw new Exception();
}
valid = false;
} catch (NumberFormatException ne) {
System.out.println("Please enter a valid zip code");
} catch (Exception e) {
System.out.printf("A zip code should be 5 numbers long");
} //end catch
} //end while
return strOut;
}//end collectZipcode method
//*************************************************************************
public static String collectEmail(String messageIn) {
String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
Scanner input = new Scanner(System.in);
String strOut = "";
boolean valid = true;
System.out.println(messageIn);
while (valid) {
try {
strOut = input.nextLine();
CharSequence emailChk = strOut;
Matcher matcher = pattern.matcher(emailChk);
if (!matcher.matches()) {
throw new Exception();
}
valid = false;
} catch (Exception e) {
System.out.printf("Please try again with a valid email "
+ "address\n");
} //end catch
} //end while
return strOut;
}//end collectEmail method
//*************************************************************************
public static Double collectWage(String messageIn) {
Scanner input = new Scanner(System.in);
double dblOut = 0;
boolean valid = true;
System.out.println(messageIn);
while (valid) {
try {
dblOut = input.nextDouble();
valid = false;
} catch (InputMismatchException ie) {
input.nextLine();
System.out.println("You must enter a whole number ");
} //end catch
} //end while
return dblOut;
}//end collectInt method
//*************************************************************************
public static String collectPhone(String messageIn) {
String expression = "^\\(?(\\d{3})\\)?[- ]?(\\d{3})[- ]?(\\d{4})$";
Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
Scanner input = new Scanner(System.in);
String strOut = "";
boolean valid = true;
System.out.println(messageIn);
while (valid) {
try {
strOut = input.nextLine();
CharSequence phoneChk = strOut;
Matcher matcher = pattern.matcher(phoneChk);
if (!matcher.matches()) {
throw new Exception();
}
valid = false;
} catch (Exception e) {
System.out.printf("Please try again with a valid phone "
+ "number\n");
} //end catch
} //end while
return strOut;
}//end collectPhone method
//*************************************************************************
public static String collectSsn(String messageIn) {
String expression = "^\\d{3}[- ]?\\d{2}[- ]?\\d{4}$";
Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
Scanner input = new Scanner(System.in);
String strOut = "";
boolean valid = true;
System.out.println(messageIn);
while (valid) {
try {
strOut = input.nextLine();
CharSequence ssnChk = strOut;
Matcher matcher = pattern.matcher(ssnChk);
if (!matcher.matches()) {
throw new Exception();
}
valid = false;
} catch (Exception e) {
System.out.printf("Please try again with a valid social security "
+ "number\n");
} //end catch
} //end while
return strOut;
}//end collectSsn
} //end Validate Class
提前感谢您的所有帮助。