本文介绍了扫描器nextLine()NoSuchElementException的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我已经为Bukkit插件编程了一段时间了，这个问题让我很头疼.我正在尝试使用扫描仪从文件中读取一行，并将:"之前的行中的所有内容添加到HashSet中.每次尝试时，我都会收到一个NoSuchElementException，看起来像这样:
I've been programming a Bukkit plugin for a while now, and this one issue has me stumped. I'm trying to read a line from a file using a Scanner, and add everything on the line before ": " to a HashSet. Every time I try, I get a NoSuchElementException, looking like this:
21:01:01 [SEVERE] Could not pass event PlayerLoginEvent to ServerProtect
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:341)
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62)
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:477)
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:462)
at net.minecraft.server.ServerConfigurationManagerAbstract.attemptLogin(
ServerConfigurationManagerAbstract.java:273)
at net.minecraft.server.NetLoginHandler.d(NetLoginHandler.java:112)
at net.minecraft.server.NetLoginHandler.c(NetLoginHandler.java:41)
at net.minecraft.server.DedicatedServerConnectionThread.a(DedicatedServe
rConnectionThread.java:44)
at net.minecraft.server.DedicatedServerConnection.b(SourceFile:29)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:578)
at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:213)
at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:474)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:406)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
Caused by: java.util.NoSuchElementException: No line found
at java.util.Scanner.nextLine(Unknown Source)
at com.gmail.thecotlsdragon98.ServerProtect.AltAccounts.CheckForUsedIP(A
ltAccounts.java:49)
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 org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:339)
... 13 more
这是我尝试做上面解释的课程.
This is the class where I try to do what I explained above.
package com.gmail.thecotlsdragon98.ServerProtect;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashSet;
import java.util.Scanner;
import org.bukkit.ChatColor;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerLoginEvent;
import org.bukkit.event.player.PlayerLoginEvent.Result;
import org.bukkit.event.server.PluginDisableEvent;
import org.bukkit.event.server.PluginEnableEvent;
public class AltAccounts implements Listener
{
ServerProtect plugin;
public AltAccounts(ServerProtect instance){
plugin = instance;
}
File usersFile;
FileWriter outputFile;
PrintWriter out;
Scanner in;
HashSet<String> players = new HashSet<String>();
StringBuffer buffer = new StringBuffer();
@EventHandler
public void newUsersFile(PluginEnableEvent event) throws IOException{
if(event.getPlugin() == plugin){
usersFile = new File("plugins\\ServerProtect\\users.yml");
if(!usersFile.exists()){
usersFile.createNewFile();
}
}
}
@EventHandler
public void CheckForUsedIP(PlayerLoginEvent event) throws IOException{
outputFile = new FileWriter(usersFile, true);
out = new PrintWriter(outputFile);
in = new Scanner(new FileReader(usersFile));
String[] nameandIP;
String name;
String IP;
String line = in.nextLine();
while(in.hasNextLine() && !in.nextLine().isEmpty()){
players.add(line.split(": ")[0]);
if(!players.contains(event.getPlayer().getName())){
out.println(event.getPlayer().getName() + ": " + event.getAddress().getHostAddress());
out.close();
}
}
if(!in.hasNextLine() || in.nextLine().isEmpty()){
if(!players.contains(event.getPlayer().getName())){
out.println(event.getPlayer().getName() + ": " + event.getAddress().getHostAddress());
out.close();
players.clear();
}
}
if(!plugin.getConfig().getBoolean("alts.kick-on-login")){
while(in.hasNextLine()){
nameandIP = in.nextLine().split(": ");
name = nameandIP[0];
IP = nameandIP[1];
if(event.getAddress().getHostAddress().equals(IP) && !event.getPlayer().getName().equals(name)){
for(final Player player : plugin.getServer().getOnlinePlayers()){
if(player.hasPermission("serverprotect.alts.notify")){
player.sendMessage(ChatColor.RED + event.getPlayer().getName() + " has the same IP as " + name + " (" + event.getAddress().getHostAddress() + ")");
}
}
}
}
}
else if(plugin.getConfig().getBoolean("alts.kick-on-login")){
while(in.hasNextLine()){
nameandIP = in.nextLine().split(": ");
name = nameandIP[0];
IP = nameandIP[1];
if(event.getAddress().getHostAddress().equalsIgnoreCase(IP)){
event.setKickMessage("The IP address you've logged in with is used. Alternate account?");
event.setResult(Result.KICK_OTHER);
}
}
}
}
public void Disable(PluginDisableEvent event)throws IOException{
if(event.getPlugin() == plugin){
in.close();
}
}
}
有人告诉我，我两次调用in.nextLine()，当我寻求有关如何解决它的建议时，他只是不理我.任何帮助，我们将不胜感激.
I've been told that I'm calling in.nextLine() twice, and when I asked for advice on how to fix it he just ignored me. Any help is greatly appreciated.
推荐答案
尝试一下:
import java.io.*;
import java.lang.*;
import java.util.*;
public class test {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
while(in.hasNextLine()) {
String line = in.nextLine();
String parse = line.substring(0, line.lastIndexOf(':'));
System.out.println(parse);
}
}
}
这篇关于扫描器nextLine()NoSuchElementException的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！