尝试写入文件后，我的 arraylist<"obj"> 变为空。
在 WriteToFile 类中，arraylist 信息在执行最后一行后变为 null
writer.write(info.get(i).getIpadd().toString()+"\n");
当我将另一个列表写入文件时它适用于第一个实例，但当我运行它第二个实例时它不起作用。我不明白为什么会这样。下面是整个代码和堆栈跟踪。
写入文件类：
public class WriteToFile {
public WriteToFile(ArrayList<Information> info,String location)
{
FileWriter writer=null;
try
{
writer = new FileWriter(location);
System.out.println(info.size());
for(int i=0;i<info.size()-1;i++)
{
writer.write(info.get(i).getDate().toString()+",");
writer.write(info.get(i).getAccount().toString()+",");
writer.write(info.get(i).getStatus().toString()+",");
writer.write(info.get(i).getIpadd().toString()+"\n");
System.out.println(info.get(i).getAccount());
}
}
catch(Exception e)
{
e.printStackTrace();
System.out.println(e.getMessage());
}
finally
{
try {
writer.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
堆栈跟踪：
java.lang.NullPointerException
at WriteToFile.<init>(WriteToFile.java:17)
at Gen_Report.<init>(Gen_Report.java:45)
at Gen_Report.main(Gen_Report.java:57)
主要的：
public class Gen_Report {
public Gen_Report()
{
// TODO Auto-generated constructor stub
//locate file and read all text from .log file to .csv
//file is found.so read text from it and extract all date/time, email add ,accepts and rejects,ip add, delete
Date date=new Date();
String[] dateTokens=date.toString().split(" ");
String dateString=dateTokens[2]+dateTokens[1]+dateTokens[5]+"_"+dateTokens[3].substring(0, 2)+dateTokens[3].substring(3,5)+dateTokens[3].substring(6, 8);
String logFileLocation = "/Users/gundu_87/Documents/workspace/GenFLRReport/";
ReaderFromLog rfl = new ReaderFromLog(logFileLocation+"radsecproxy.log");
//include duplicates
WriteToFile wtf = new WriteToFile(rfl.log,logFileLocation+dateString+"_FLRlogduplicates.txt");
//exclude duplicates
RemoveDuplicatesInList rdil = new RemoveDuplicatesInList(logFileLocation+dateString+"_FLRlogduplicates.txt");
for(int i=0;i<rdil.log.size();i++)
{
System.out.println(rdil.log.get(i).getAccount());
}
wtf = new WriteToFile(rdil.log,logFileLocation+dateString+"_FLRlog.txt");
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Gen_Report gr= new Gen_Report();
}
}
信息类：
public class Information {
private String ipadd;
private String status;
private String account;
private String date;
public String getIpadd() {
return ipadd;
}
public void setIpadd(String ipadd) {
this.ipadd = ipadd;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getAccount() {
return account;
}
public void setAccount(String account) {
this.account = account;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
}
ReaderFromLog 类
public class ReaderFromLog {
Scanner s1 = null;
String line=null;
ArrayList<Information> log;
public ReaderFromLog(String logFileLocation) {
// TODO Auto-generated constructor stub
File logFile = new File(logFileLocation);
if(!logFile.exists())
{
System.err.println("File not found");
System.exit(1);
}
else
{
try
{
s1 = new Scanner(new FileReader(logFile));
} catch (FileNotFoundException e)
{
System.err.print("File not found");
}
}
log=new ArrayList<Information>();
//store into a array
//exclude any repeats
do{
line=s1.nextLine();
Information newUser = new Information();
if(line.contains("Access-Accept for user"))
{
newUser.setStatus("Accept");
String[] sb=line.split(" ");
newUser.setAccount(sb[7]);
int idx_Ipadd = 0;
for(int i=0;i<sb.length;i++)
if (sb[i].contentEquals("to"))
idx_Ipadd=i;
newUser.setIpadd(sb[idx_Ipadd+1]+ " " + sb[idx_Ipadd+2]);
newUser.setDate(sb[0]+ " "+sb[1] + " " +sb[2]+" " + sb[3].substring(0, 4));
log.add(newUser);
}
else if(line.contains("Access-Reject for user"))
{
newUser.setStatus("Reject");
String[] sb=line.split(" ");
newUser.setAccount(sb[7]);
int idx_Ipadd = 0;
for(int i=0;i<sb.length;i++)
if (sb[i].contentEquals("to"))
idx_Ipadd=i;
newUser.setIpadd(sb[idx_Ipadd+1]+ " " + sb[idx_Ipadd+2]);
newUser.setDate(sb[0]+ " "+sb[1] + " " +sb[2]+" " + sb[3].substring(0, 4));
log.add(newUser);
}
}while(s1.hasNextLine());
}
}
删除重复类：
public class RemoveDuplicatesInList {
Scanner s1 = null;
String line=null;
ArrayList<Information> log;
public RemoveDuplicatesInList(String duplicateFileLocation)
{
// TODO Auto-generated constructor stub
File logFile = new File(duplicateFileLocation);
if(!logFile.exists())
{
System.err.println("File not found");
System.exit(1);
}
else
{
try
{
s1 = new Scanner(new FileReader(logFile));
} catch (FileNotFoundException e)
{
System.err.print("File not found");
}
}
log=new ArrayList<Information>();
//store into a array
//exclude any repeats
do{
boolean sameAccount=false;
line=s1.nextLine();
Information newUser = new Information();
if(line.contains("Accept"))
{
newUser.setStatus("Accept");
String[] sb=line.split(",");
sameAccount=false;
for(int i=0;i<log.size();i++)
if(log.get(i).getAccount().contentEquals(sb[1]))
{
sameAccount=true;
break;
}
if(!sameAccount)
{
newUser.setAccount(sb[1]);
newUser.setIpadd(sb[3]);
newUser.setDate(sb[0]);
log.add(newUser);
}
}
else if(line.contains("Reject"))
{
newUser.setStatus("Reject");
String[] sb=line.split(",");
for(int i=0;i<log.size();i++)
if(log.get(i).getAccount().contentEquals(sb[1]))
{
sameAccount=true;
break;
}
if(!sameAccount)
{
newUser.setAccount(sb[1]);
newUser.setIpadd(sb[3]);
newUser.setDate(sb[0]);
log.add(newUser);
}
}
}while(s1.hasNextLine());
}
}