I have a simple login program and my very simple unsecure database is text file, which is this
mohammed
badpassword1
fahad
badpassword2
saad
Badpassword3
faisal
badpassword4
jack
badpasswod5
and I have this code reading every line in a text file and print it
I just want to pass the username and get it password which is the next line but I couldn't
I tried to store it in array and get the password from next element from the username but all the elements are NULL, I don't know why
can I get some help?
public static void main(String[] args) throws Exception{
try {
FileReader reader = new FileReader("/Users/mohammed/Downloads/testFile.txt");
BufferedReader bufferedReader = new BufferedReader(reader);
String line = new String();
while ((line = bufferedReader.readLine()) != null) {
System.out.println(line);
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
I know this might be a little stupid solution, but it should work.
public class User {
private String username;
private String password;
// getters, setters, toString
}
....
public static void main(String[] args) throws Exception{
try {
FileReader reader = new FileReader("/Users/mohammed/Downloads/testFile.txt");
BufferedReader bufferedReader = new BufferedReader(reader);
String line = new String();
// let's have this one to hold users
List<User> users = new ArrayList<>();
int index = 1;
User user = new User();
while ((line = bufferedReader.readLine()) != null) {
now we will read line by line, create User objects and put them into the list
System.out.println(line);
if (index > 2) {
// means you are reading the third line, so that's the name of the next user
users.add(user); // save previous user
user = new User(); // object to hold new one
index = 1; // reset index
}
if (index == 1) {
user.setUserName(line);
}
if (index == 2) {
user.setPassword(line);
}
index++;
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
// and once you have all the users in the list you can do whatever you need
//e.g. print all users
users.forEach(System.out::println);
// find the user you need, e.g. with name 'fahad'
final User fahad = users.stream().filter(u -> { return u.getUserName().equals("fahad")}).findFirst();
System.out.println(fahad.getPassword()); // for instance
}
Compare the line you currently read to the line you are looking for (username) and print the next one
public static void main(String[] args) throws Exception{
try {
FileReader reader = new FileReader("/Users/mohammed/Downloads/testFile.txt");
BufferedReader bufferedReader = new BufferedReader(reader);
String username="mohammed";
String line = new String();
while ((line = bufferedReader.readLine()) != null)
if(line.equals(username){
System.out.println(bufferedReader.readLine());
break;
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
Related
Below is the code:
InputStream in = channelExec.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
} catch (JSchException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
The following is my output:
Context successfully set
Script started
LXKADMIN|In/OutBoundValidation|-|50149.11065.26960.11788|inbound=OFF|outbound=OFF
inbound=OFF|outbound=OFF
Script complete
STEP 1: COMPLETED
PASSED: step1
I want to fetch the line 5 "inbound=OFF|outbound=OFF" and check if its value is matching "inbound=OFF|outbound=OFF" then my test case will pass else it will fail.
The TCL Script is:
tcl;
eval {
puts "Script started"
set schemaValidationStr [mql temp query bus LXKADMIN In/OutBoundValidation * select id description dump '|']
puts $schemaValidationStr
set schemaValidation [string range $schemaValidationStr 57 end]
puts $schemaValidation
puts "Script complete"
}
Any suggestion will be really helpful.
If your question is just how to verify that the output returned by your TCL script, contains a specific line, than you might try this:
public static final int CHECK_LINE_NR = 4;
public static final String EXPECTED_LINE_VALUE = "inbound=OFF|outbound=OFF";
public boolean verifyScriptOutput(ChannelExec channel)
throws IOException
{
// Check all lines in output
BufferedReader reader = new BufferedReader(new InputStreamReader(channel.getInputStream()));
String line;
int linenr = 0;
while ((line = reader.readLine()) != null)
{
linenr++;
if (linenr == CHECK_LINE_NR)
return (line.equals(EXPECTED_LINE_VALUE));
}
// If we get here, output has less lines
return (false);
} // verifyScriptOutput
The point at which you are reasoning is not possible because you can not access the console and see what is visualized. Instead you should process the input that the console gets, and outputs it, which is the line variable in your case.
If for you is enough to see that inbound=OFF|outbound=OFF you can search that substring in the line like this:
if(line.indexOf("inbound=OFF|outbound=OFF") != -1) {
// you have a match
}
I'm not sure I understood the question, but you might try this:
public static final int CHECK_LINE_NR = 4;
public static final String CHECK_LINE_VALUE = "inbound=OFF|outbound=OFF";
InputStream in = channelExec.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line;
int linenr;
boolean line_check_passed;
linenr = 0;
line_check_passed = false;
while ((line = reader.readLine()) != null) {
linenr++;
if (linenr == CHECK_LINE_NR)
line_check_passed = line.equals(CHECK_LINE_VALUE);
System.out.println(line);
}
} catch (JSchException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
public static boolean check(InputStream in, int line, String expected) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
int i = 0;
String str;
while ((str = reader.readLine()) != null) {
if (i < line)
i++;
else
return expected.equals(str);
}
return false;
}
I need some help with reading line by line from a file then put it into a class.
My idea is like this: I've saved everything in a text file, it's about 500 lines but this can change that's why I wan't the line number reader and then lnr/5 to get how many times I'll need to run the for loop. I wan't it to first take line 1,2,3,4,5 into a object, then 6,7,8,9,10 and so on. So basically I need each 5 lines go in seperatley.
Code:
public static void g_txt() {
LineNumberReader lnr;
String[] text_array = new String[500];
int nu = 0;
try {
lnr = new LineNumberReader(new FileReader(new File("test.txt")));
lnr.skip(Long.MAX_VALUE);
//System.out.println(lnr.getLineNumber());
lnr.close();
BufferedReader br = new BufferedReader(new FileReader("test.txt"));
String line;
while ((line = br.readLine()) != null) {
text_array[nu] = line;
nu++;
}
} catch (IOException e) {
}
}
as you can see, I now has it in an array. Now I need it to make so 1,2,3,4,5 and so on go in to this:
filmer[antalfilmer] = new FilmSvDe(line1);
filmer[antalfilmer].s_filmbolag(line2);
filmer[antalfilmer].s_producent(line3);
filmer[antalfilmer].s_tid(line4);
filmer[antalfilmer].s_betyg(line5);
filmer[antalfilmer].s_titel(line1);
then antalfilmer++.
public static void g_txt() {
String[] text_array = new String[5];
int nu = 0;
try {
BufferedReader br = new BufferedReader(new FileReader("test.txt"));
String line;
while ((line = br.readLine()) != null) {
text_array[nu] = line;
nu++;
if (nu == 5) {
nu = 0;
makeObject(text_array);
}
}
} catch (IOException e) {
}
}
private static void makeObject(String[] text_array) {
// do your object creation here
System.out.println("_________________________________________________");
for (String string : text_array) {
System.out.println(string);
}
System.out.println("_________________________________________________");
}
Try this.
ive gotten this far, but this doesnt work to read in the file, thats the part im stuck on. i know that you need to use the scanner, but im not sure what im missing here. i think it needs a path to the file also, but i dont know where to put that in
public class string
{
public static String getInput(Scanner in) throws IOException
{
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter file");
String filename =keyboard.next();
File inputFile = new File(filename);
Scanner input = new Scanner(inputFile);
String line;
while (input.hasNext())
{
line= input.nextLine();
System.out.println(line);
}
input.close();
}
if(filename.isEmpty())
{
System.out.println("Sorry, there has been an error. You must enter a string! (A string is some characters put together.) Try Again Below.");
return getInput(in);
}
else
{
return filename;
}
}
public static int getWordCount(String input)
{
String[] result = input.split(" ");
return result.length;
}
public static void main(String[] args)
{
DecimalFormat formatter = new DecimalFormat("0.##");
String input = getInput(new Scanner(System.in));
float counter = getWordCount(input);
System.out.println("The number of words in this string ("+input+") are: " + counter);
Scanner keyboard= new Scanner(System.in);
}
}
//end of code
First of all, when doing file I/O in Java, you should properly handle all exceptions and errors that can occur.
In general, you need to open streams and resources in a try block, catch all exceptions that happen in a catch block and then close all resources in a finally block. You should read up more on these here as well.
For using a Scanner object, this would look something like:
String token = null;
File file = null;
Scanner in = null;
try {
file = new File("/path/to/file.txt");
in = new Scanner(file);
while(in.hasNext()) {
token = in.next();
// ...
}
} catch (FileNotFoundException e) {
// if File with that pathname doesn't exist
e.printStackTrace();
} finally {
if(in != null) { // pay attention to NullPointerException possibility here
in.close();
}
}
You can also use a BufferedReader to read a file line by line.
BufferedReader reader = new BufferedReader(new FileReader("/path/to/file.txt"));
String line = null;
while ((line = reader.readLine()) != null) {
// ...
}
With added exception handling:
String line = null;
FileReader fReader = null;
BufferedReader bReader = null;
try {
fReader = new FileReader("/path/to/file.txt");
bReader = new BufferedReader(fReader);
while ((line = bReader.readLine()) != null) {
// ...
}
} catch (FileNotFoundException e) {
// Missing file for the FileReader
e.printStackTrace();
} catch (IOException e) {
// I/O Exception for the BufferedReader
e.printStackTrace();
} finally {
if(fReader != null) { // pay attention to NullPointerException possibility here
try {
fReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(bReader != null) { // pay attention to NullPointerException possibility here
try {
bReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In general, use the Scanner for parsing a file, and use the BufferedReader for reading the file line by line.
There are other more advanced ways to perform reading/writing operations in Java. Check out some of them here
I have a text file with more than 20,000 lines and i need to extract specific line from it. The output of this program is completely blank file.
There are 20,000 lines in the txt file and this ISDN line keeps on repeating lots of time each with different value. My text file contains following data.
RecordType=0(MOC)
sequenceNumber=456456456
callingIMSI=73454353911
callingIMEI=85346344
callingNumber
AddInd=H45345'1
NumPlan=H34634'2
ISDN=94634564366 // Need to extract this "ISDN" line only
public String readTextFile(String fileName) {
String returnValue = "";
FileReader file = null;
String line = "";
String line2 = "";
try {
file = new FileReader(fileName);
BufferedReader reader = new BufferedReader(file);
while ((line = reader.readLine()) != null) {
// extract logic starts here
if (line.startsWith("ISDN") == true) {
System.out.println("hello");
returnValue += line + "\n";
}
}
} catch (FileNotFoundException e) {
throw new RuntimeException("File not found");
} finally {
if (file != null) {
try {
file.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return returnValue;
}
We will assume that you use Java 7, since this is 2014.
Here is a method which will return a List<String> where each element is an ISDN:
private static final Pattern ISDN = Pattern.compile("ISDN=(.*)");
// ...
public List<String> getISDNsFromFile(final String fileName)
throws IOException
{
final Path path = Paths.get(fileName);
final List<String> ret = new ArrayList<>();
Matcher m;
String line;
try (
final BufferedReader reader
= Files.newBufferedReader(path, StandardCharsets.UTF_8);
) {
while ((line = reader.readLine()) != null) {
m = ISDN.matcher(line);
if (m.matches())
ret.add(m.group(1));
}
}
return ret;
}
I want to read the 2nd line of text from a file and have that put into an array. I already have it working on the first line.
[ Code removed as requested ]
The while loop above shows how I read and save the 1st line of the text file into an array. I wish to repeat this process from the 2nd line only into a different array.
File Content:
Sofa,Armchair,Computer Desk,Coffee Table,TV Stand,Cushion,Bed,Mattress,Duvet,Pillow
599.99,229.99,129.99,40.00,37.00,08.00,145.00,299.99,24.99,09.99
Just get rid of the first readLine() call, and move the String.split() call into the loop.
Simply use the BufferedReader class to read the entire file and then manipulate the String output.
Something along these lines
public static String readFile(String fileName) throws IOException {
String toReturn = "";
BufferedReader br = null;
try {
String sCurrentLine;
br = new BufferedReader(new FileReader("test.txt"));
while ((sCurrentLine = br.readLine()) != null) {
toReturn = toReturn+"\n"+sCurrentLine;
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null)br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
return toReturn;
}
would yield a String which can then be easily used.
public static void main(String[] args)
{
String filePath = args[0];
String[] lineElements = getLine(filePath,2).split(",");
}
public static String getLine(String path,int line)
{
List<String> cases = new ArrayList<String>();
try{
BufferedReader br = new BufferedReader(new FileReader(path));
String currLine = "";
while((currLine = br.readLine()) != null){
cases.add(currLine);
}
}catch(IOException ex){
ex.printStackTrace();
}
return cases.get(line - 1);//2nd line
}