[英]ERROR Scanning textFile shows error “ Exception in thread ”AWT-EventQueue-0“ java.util.NoSuchElementException”
public class checkDuplicateNames1 {
public boolean checkDuplicateNames1(String name , String surname){
boolean found = false;
File file = new File("transactions.txt");
try {
Scanner sc = new Scanner(new File("transactions.txt"));
sc.useDelimiter("/");
while(sc.hasNext()){
String userName = sc.next();
String userLastName = sc.next();
String userCash = sc.next();
String paidStatus = sc.next();
if((userName.equals(name)&&userLastName.equals(surname))){
found = true;
}
else
{
found = false;
}
}
} catch (FileNotFoundException ex) {
Logger.getLogger(checkDuplicateNames.class.getName()).log(Level.SEVERE, null, ex);
}
return found;
}
}
When i am in the point when i use the "boolean checkDuplicateNames1" method i get this error 当我使用“ boolean checkDuplicateNames1”方法时,出现此错误
Exception in thread "AWT-EventQueue-0" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:862)
at java.util.Scanner.next(Scanner.java:1371)
at Lending.checkDuplicateNames1.checkDuplicateNames1(checkDuplicateNames1.java:41)
at Lending.Loan.jButton1ActionPerformed(Loan.java:250)
at Lending.Loan.access$200(Loan.java:24)
at Lending.Loan$3.actionPerformed(Loan.java:137)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
I tried to use different filereader like bufferedReader it's just the same , 我试图使用像bufferedReader这样的不同文件读取器,它是相同的,
here's the "Loan class " method that uses "checDuplicateNames1" method 这是使用“ checDuplicateNames1”方法的“贷款类”方法
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String name = jTextField1.getText();
String surname = jTextField4.getText();
String cash = jTextField5.getText();
System.out.println("loan clicked");
try {
String info = name + "/" + surname + "/" + cash + "/" + "unpaid";
checkDuplicateNames1 c = new checkDuplicateNames1();
boolean duplicated = c.checkDuplicateNames1(name,surname);
if(duplicated == true){
System.out.println("duplicated");
this.currentName = name;
this.currentSurname = surname;
JOptionPane.showMessageDialog(null,"Person already in the Record ");
wannaAddLoanValue w = new wannaAddLoanValue(name,surname,cash);
w.show();
}
else
{
File file = new File("transactions.txt");
PrintWriter writer = new PrintWriter(new FileWriter(file,true));
String info1 = name + "/" + surname + "/" + cash + "/" + "unpaid";
writer.println(info1);
writer.close();
}
} catch (FileNotFoundException ex) {
Logger.getLogger(Loan.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(Loan.class.getName()).log(Level.SEVERE, null, ex);
}
}
and Also the text in the file are like this 并且文件中的文本也像这样
rodchris/toledo/200/unpaid
yannie/taub/890/unpaid
You should always call sc.hasNext()
before sc.next();
你应该总是调用
sc.hasNext()
之前sc.next();
. 。
while(sc.hasNext()){
// This line is OK
String userName = sc.next();
// The following lines can cause NoSuchElementException
String userLastName = sc.next();
String userCash = sc.next();
String paidStatus = sc.next();
checkDuplicateNames1()
can be refactored as follows: checkDuplicateNames1()
可以按以下方式重构:
public boolean checkDuplicateNames1(String name, String surname) {
boolean found = false;
try (Scanner sc = new Scanner(new File("transactions.txt"))) {
sc.useDelimiter("/");
String userName = sc.hasNext() ? sc.next() : null;
String userLastName = sc.hasNext() ? sc.next() : null;
return userName != null && userLastName != null && userName.equals(name) && userLastName.equals(surname);
} catch (FileNotFoundException ex) {
Logger.getLogger(checkDuplicateNames.class.getName()).log(Level.SEVERE, null, ex);
}
return found;
}
which line in ur class is 41
? 你班上哪一行是
41
? ie which next()
causes the error, 即哪个
next()
导致错误,
i think hasNext()
considers the whole current input as 1 token, but when you call next()
several times, you got only first 1 then the exception, to fix this i think you have to check for hasNext()
before each next()
我认为
hasNext()
认为,当前整个输入为1个令牌,但是当你调用next()
几次,你只拿到了第一个1个例外,要解决这个问题,我认为你必须检查hasNext()
前各next()
while(sc.hasNext()){
String userName="",userLastName="",userCash="",paidStatus="";
//first one already checked in while(...)
userName = sc.next();
if(sc.hasNext())
userLastName = sc.next();
if(sc.hasNext())
userCash = sc.next();
if(sc.hasNext())
paidStatus = sc.next();
//... rest of code
in the rest of your code you may want to check each variable is empty 在其余的代码中,您可能需要检查每个变量是否为空
if(!userLastName.isEmpty()) ...
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.