Question

我有这个方法应该从txt文件中读取，然后在交互窗格中打印出读取的信息。该方法有效，我获取了文件中的所有数据，但最后我还打印出了java.util.NoSuchElementException。我知道这意味着扫描程序已到达文件的末尾，没有更多数据要读取，但不知道如何解决问题。有人能帮帮我吗？

public void parseRecord(String recordFileName){

File recordFile = null;
Fruit fruit = null;
String color = null, name = null;
Scanner sc = null;
PrintWriter output = null;      

try{    
  recordFile = new File(recordFileName);
  sc = new Scanner(recordFile);
  sc.useDelimiter("- *");

  while(sc.hasNext()){
    color = sc.next();
    name = sc.next();

    fruit = new Fruit(color, name);
    System.out.println(fruit);
  }
  sc.close();
}catch(Exception e){
  System.out.println(e);
}

}

  java.util.NoSuchElementException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at ReadFruits.parseRecord(ReadFruits.java:21)
at ReadFruits.main(ReadFruits.java:41)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:271)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at edu.rice.cs.dynamicjava.symbol.JavaClass$JavaMethod.evaluate(JavaClass.java:362)
at edu.rice.cs.dynamicjava.interpreter.ExpressionEvaluator.handleMethodCall(ExpressionEvaluator.java:92)
at edu.rice.cs.dynamicjava.interpreter.ExpressionEvaluator.visit(ExpressionEvaluator.java:84)
at koala.dynamicjava.tree.StaticMethodCall.acceptVisitor(StaticMethodCall.java:121)
at edu.rice.cs.dynamicjava.interpreter.ExpressionEvaluator.value(ExpressionEvaluator.java:38)
at edu.rice.cs.dynamicjava.interpreter.ExpressionEvaluator.value(ExpressionEvaluator.java:37)
at edu.rice.cs.dynamicjava.interpreter.StatementEvaluator.visit(StatementEvaluator.java:106)
at edu.rice.cs.dynamicjava.interpreter.StatementEvaluator.visit(StatementEvaluator.java:29)
at koala.dynamicjava.tree.ExpressionStatement.acceptVisitor(ExpressionStatement.java:101)
at edu.rice.cs.dynamicjava.interpreter.StatementEvaluator.evaluateSequence(StatementEvaluator.java:66)
at edu.rice.cs.dynamicjava.interpreter.Interpreter.evaluate(Interpreter.java:77)
at edu.rice.cs.dynamicjava.interpreter.Interpreter.interpret(Interpreter.java:47)
at edu.rice.cs.drjava.model.repl.newjvm.InterpreterJVM.interpret(InterpreterJVM.java:246)
at edu.rice.cs.drjava.model.repl.newjvm.InterpreterJVM.interpret(InterpreterJVM.java:220)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

我认为问题可能出在我创建的txt文件中。我使用 - 作为分隔符，在文件的最后一行我不应该 - ，意思是橙色 - 橙色 - Green- Apple

当我这样做时，我不再收到错误

Answer 1

您遇到的一个问题是，每次使用hasNext时都不会检查next：

while(sc.hasNext()) {
    String color = sc.next();
    if(sc.hasNext()) {
        String name = sc.next();
        Fruit fruit = new Fruit(color, name);
        System.out.println(fruit);
    }
}

java I / O中的NoSuchElement异常

1 个答案: