I have a really big program that needs to check what character is typed this is just a part of the broken part. So it worked when I had it logging each character typed. But when I try to add each character to the string so when they type the word hi it looks like this:
hi
and NOT
h
i
No matter what i try it either gives me the first value typed and doesnt add each character to the string I also want it to print out the string every 5 seconds im not sure if I did that right either but it might be correct.
String log = " ";
if(event.getVirtualKeyCode() == GlobalKeyEvent.VK_SPACE){
log = log + "";
}
if(event.getVirtualKeyCode() == GlobalKeyEvent.VK_BACK){
log = log + "[BACKSPACE]";
}
String timestamp = new SimpleDateFormat("yyyy:MM:dd HH:mm:ss").format(Calendar.getInstance().getTime());
while(true){
try {
Thread.sleep(5000);
System.out.println("[" + timestamp + "]" + log);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
}
Try to declare a new string:
String log = new String(" ");
Related
I am pretty new to Java and I am doing this project. I keep getting the following error message while I click a jButton (submitButton) in the runtime, and I am not sure why as it is not telling which line the problem is at.
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
Below is my code, I was wondering if anybody could help? Maybe help me find the error, or tell me what the error message means. Thank you!
private void submitButtonActionPerformed(java.awt.event.ActionEvent evt) {
String fullName = nameText.getText();
String email = emailText.getText();
String address = addressText.getText();
String phoneNumber = phoneText.getText();
// sets either true or false to membershipSelected if a plan is selected
boolean membershipSelected = standardMembership.isSelected() || silverMembership.isSelected() || goldMembership.isSelected();
double total = 0;
// checks if the text entered in phone number text field can be parsed to an integer
// this is only possible if it is a number, if it is a string, then error pop-up appears
try {
int phone = Integer.parseInt(phoneText.getText());
}
catch(Exception e) {
javax.swing.JOptionPane.showMessageDialog(keepStrongMain.this, "This is not a valid phone number, please try again!");
}
// checks if email text field does not contain "#" or a domain
if(!email.contains("#") || !email.contains(".com") && !email.contains(".de") && !email.contains(".co.uk")){
javax.swing.JOptionPane.showMessageDialog(keepStrongMain.this, "This is not a valid email address, please try again!");
}
else {
CardLayout card =(CardLayout)mainPanel.getLayout();
card.show(mainPanel, "card3");
}
// checks if length of phone number is 11, if not shows error pop-up
int phoneLength = Integer.parseInt(phoneText.getText());
if(phoneLength != 11){
javax.swing.JOptionPane.showMessageDialog(keepStrongMain.this, "This phone number is not long enough, please try again!");
}
else {
CardLayout card =(CardLayout)mainPanel.getLayout();
card.show(mainPanel, "card3");
}
// checks if a plan is selected, if not shows error pop-up
if(membershipSelected){
CardLayout card =(CardLayout)mainPanel.getLayout();
card.show(mainPanel, "card3");
}
else {
javax.swing.JOptionPane.showMessageDialog(keepStrongMain.this, "Please select a membership!");
}
// sets the final overview to an empty string that can be added to with selections later
String overview = "";
if (standardMembership.isSelected()){
overview = overview + " " + standardMembership.getText() + '\n';
total = 200;
}
if (silverMembership.isSelected()){
overview = overview + " " + silverMembership.getText() + '\n';
total = 450;
}
if (goldMembership.isSelected()){
overview = overview + " " + goldMembership.getText() + '\n';
total = 600;
}
}
You have two places where you perform Integer.parseInt(phoneText.getText());
At the first time, the parsing is surrounded by a try-catch block and that handles the NumberFormatException that would be thrown in case phoneText.getText() is empty or not a number.
The second time, the parsing is not surrounded by any try-catch. This time the NumberFormatException thrown is unhandled and hence you are seeing the Exception.
You should ideally parse the phoneText.getText() once and have your conditions modified accordingly.
I'm trying to get the input that the user enters to go to lower-case and then put the first character in the input to upper-case. For example, If I enter aRseNAL for my first input, I want to format the input so that it will put "Arsenal" into the data.txt file, I'm also wondering if there's a way to put each first character to upper-case if there's more than one word for a team ie. mAN uNiTeD formatted to Man United to be written to the file.
The code I have below is what i tried and I cannot get it to work. Any advice or help would be appreciated.
import java.io.*;
import javax.swing.*;
public class write
{
public static void main(String[] args) throws IOException
{
FileWriter aFileWriter = new FileWriter("data.txt");
PrintWriter out = new PrintWriter(aFileWriter);
String team = "";
for(int i = 1; i <= 5; i++)
{
boolean isTeam = true;
while(isTeam)
{
team = JOptionPane.showInputDialog(null, "Enter a team: ");
if(team == null || team.equals(""))
JOptionPane.showMessageDialog(null, "Please enter a team.");
else
isTeam = false;
}
team.toLowerCase(); //Put everything to lower-case.
team.substring(0,1).toUpperCase(); //Put the first character to upper-case.
out.println(i + "," + team);
}
out.close();
aFileWriter.close();
}
}
In Java, strings are immutable (cannot be changed) so methods like substring and toLowerCase generate new strings - they don't modify your existing string.
So rather than:
team.toLowerCase();
team.substring(0,1).toUpperCase();
out.println(team);
You'd need something like:
String first = team.substring(0,1).toUpperCase();
String rest = team.substring(1,team.length()).toLowerCase();
out.println(first + rest);
Similar as #DNA suggested but that will throw Exception if String length is 1. So added a check for same.
String output = team.substring(0,1).toUpperCase();
// if team length is >1 then only put 2nd part
if (team.length()>1) {
output = output+ team.substring(1,team.length()).toLowerCase();
}
out.println(i + "," + output);
java.lang.NumberFormatException: For input string: ":"
What does this mean?
I get the above error if I run the code (below).I am a beginner here.
and..
stacktrace:[Ljava.lang.StackTraceElement;#e596c9
the code:
try
{
Class.forName("java.sql.DriverManager");
Connection con=DriverManager.getConnection("jdbc:mysql://localhost/bvdb","root","enter")
Statement stm=con.createStatement();
String m="-",t="-",w="-",th="--",f="-",st="--",s="-",runson;
if(jCheckBox1.isSelected()==true){
m="m";}
if(jCheckBox2.isSelected()==true){
t="t";}
if(jCheckBox3.isSelected()==true){
w="w";}
if(jCheckBox4.isSelected()==true){
th="th";}
if(jCheckBox5.isSelected()==true){
f="f";}
if(jCheckBox6.isSelected()==true){
st="st";}
if(jCheckBox7.isSelected()==true){
s="s";}
runson= m + t + w + th + f + st + s ;
int h1=Integer.valueOf(jTextField10.getText().substring(0,2)
int mins1=Integer.valueOf(jTextField10.getText().substring(3,5));
int h2=Integer.valueOf(jTextField12.getText().substring(0,2));
int mins2=Integer.valueOf(jTextField12.getText().substring(2,3));
Boolean x=jTextField10.getText().substring(2,3).equals(":");
Boolean y=jTextField12.getText().substring(2,3).equals(":");
String time1=jTextField10.getText().substring(0,2)+jTextField10.getText().substring (2,3)+jTextField10.getText().substring(3,5);
String time2=jTextField12.getText().substring(0,2)+jTextField12.getText().substring(2,3)+jTextField12.getText().substring(3,5);
String tfac1=jTextField13.getText();
String tfac2=jTextField14.getText();
String tfac3=jTextField15.getText();
String tfsl=jTextField16.getText();
if(Integer.valueOf(jTextField3.getText())==0){
tfac1="0";
if(Integer.valueOf(jTextField4.getText())==0){
tfac2="0";}
if(Integer.valueOf(jTextField5.getText())==0){
tfac3="0";}
if(Integer.valueOf(jTextField6.getText())==0){
tfsl="0";}
if(y==true&&x==true&&jTextField1.getText().trim().length()<=6&&jTextField2.getText().trim().length()<=30&&h1<=24&&h2<=24&&mins1<=59&&mins2<=59){
String q="INSERT INTO TRAININFO VALUE ("+jTextField1.getText()+",'"+jTextField2.getText()+"','"+jTextField9.getText()+"','"+time1+"','"+jTextField11.getText()+"','"+time2+"','"+runson+"',"+tfac1+","+tfac2+ ","+tfac3+","+tfsl+","+jTextField3.getText()+","+jTextField4.getText()+","+jTextField5.getText()+","+jTextField6.getText()+");";
stm.executeUpdate(q);
JOptionPane.showMessageDialog("ADDED");
}
}
catch (Exception e){
e.printStackTrace();
}
that means you can not convert the String ":" to Number like integer or double
see below link
http://docs.oracle.com/javase/7/docs/api/java/lang/NumberFormatException.html
According to java docs
Thrown to indicate that the application has attempted to convert a
string to one of the
numeric types, but that the string does not have the appropriate format.
It means you want to convert ":" to a number which is not allowed. Hence you are getting the exception. Better show your code
The best way you get responses faster & answered your question is posting your code.
You cannot convert String to number.
As others have said Java can't convert "15:" into a number because ":" is not a digit. And the most probable cause for this is a line like this one:
int h1 = Integer.valueOf(jTextField10.getText().substring(0,2));
where you are splitting a time string at the wrong index which is why you have ":" in it.
UPDATE
Better way of splitting a time string like "12:35:09" is by using String.split():
String timeString = "12:35:09";
String[] parts = timeString.split(":");
boolean validTimeString = parts.length == 3;
The code above will result in the following values:
timeString = "12:35:09"
parts[0] = "12"
parts[1] = "35"
parts[2] = "09"
validTimeString = true
String.split(DELIMITER) will split the string into N + 1 strings where N is the number of occurences of the DELIMITER in target string.
Problem solved.
I have two methods in my class.
private void retrieveDetails(){
List<String> details = File.getCredentials();
username = details.get(0);
pw = details.get(1);
}
private void checkCredentials() throws IOException {
retrieveDetails();
System.out.println("\nPlease enter USERNAME: ");
String usersName = scan.next();
System.out.println("\nPlease enter PASSWORD: ");
String usersPW = scan.next();
System.out.println("\nEntered details: " + usersName + ", " + usersPW);
System.out.println("\nSystems details: " + userName + ", " + pw);
if (usersName.equals(username) && usersPW.equals(pw)) {
doWork();
} else {
System.out.println("Incorrect credentials");
}
}
I thought I came up with a solution by moving the following up to where my strings are initialized.
List<String> creds = File.getCredentials();
I created a System.out statement to check if the details coming from retrieveDetails() match those entered by the users. They do match - but when the system goes to the else clause instead of executing doWork();
If what is printed is the same then try trimming before comparing. E.g.:
if (usersName.trim().equals(username.trim()) && usersPW.trim().equals(pw.trim())) {
When i have similar problem i do this simple trick:
Print the size of the strings you are comparing because sometimes you have characters like \n or \r which are not visible when you print the string.
First of all, it seems like you have a typo in sysout statement below.
System.out.println("\nEntered details: " + usersName + ", " + usersPW);
System.out.println("\nSystems details: " + userName + ", " + pw); //Should be username
Secondly, you might wanna trim the strings for better string comparison.
Sometimes strings read from file or console can contain unwanted and hard-to-catch empty strings like spaces and tabs. These can be removed by calling .trim() method on strings.
Thus, try using the following code instead:
if (usersName.trim().equals(username.trim()) && usersPW.trim().equals(pw.trim())) {
}
usersName.equals(username) && usersPW.equals(pw).
I have faced these problem also, These kind of equality always tricky, Try to trim the strings that you are going to compare, as well as if you can compare these strings based on their length.
if (usersName.trim().equalsIgnoreCase(username.trim()) && usersPW.trim().equalsIgnoreCase(pw.trim()))
or
if (usersName.trim().length()==username.trim().length && usersPW.trim().length()==pw.trim().length))
Weird problem. I run this (very elementary) procedure to find a username and password in a file, and the program should compare the password entered to the password saved. Every time, however, i get a strange String index out of range: -1 exception. I've suffered a similar problem before, however this time the indexOf('.') call is returning -1; which it doesn't like. Why is indexOf() returning -1 if it causes an error? Here's the source:
public String loginToClient() throws FileNotFoundException, IOException {
//decryptUsers();
int tries;
tries = 5;
while (tries > 0) {
System.out.println("LOGIN");
String usnm = c.readLine("Username: ");
char [] passwd = c.readPassword("Password: ");
users = new FileInputStream("users.fra");
DataInputStream dis = new DataInputStream(users);
BufferedReader br = new BufferedReader(new InputStreamReader(dis));
String logindat = br.readLine();
System.out.println(logindat);
if (logindat.contains(usnm) == null) {
System.err.println("Username not recognised, please try another or create user.");
usnm = "INV";
return usnm;
}
else {
int startUsnm = logindat.indexOf(usnm);
System.out.println("startUsnm: " + startUsnm);
String logdat = logindat.substring(startUsnm, logindat.indexOf("."));
System.out.println("logdat: " + logdat);
int endUsnm = logdat.indexOf(':');
System.out.println("endUsnm: " + endUsnm);
int usnmend = endUsnm - 1;
System.out.println("usnmend: " + usnmend);
int startPass = endUsnm + 1;
System.out.println("startPass: " + startPass);
int endPass = logdat.indexOf('.');
System.out.println("endPass: " + endPass);
String Usnm = logdat.substring(0, usnmend);
System.out.println("Usnm: " + Usnm);
int passend = endPass - 1;
System.out.println("passend: " + passend);
String Pass = logdat.substring(startPass, passend);
System.out.println("Pass: " + Pass);
char [] Passwd = Pass.toCharArray();
if (usnm.equals(Usnm)) {
if (Arrays.equals(passwd,Passwd)) {
System.out.println ("Logged in. Welcome, " + usnm + ".");
String data = "LOGIN: " + usnm;
printLog(data);
//encryptUsers();
return usnm;
}
else {
System.out.println ("Incorrect password, please try again.");
String data = "PASWFAIL: " + usnm;
printLog(data);
tries -= 1;
}
}
else {
System.out.println ("Username not recognised.");
printLog("USNAMFAIL");
usnm = "INV";
return usnm;
//encrytUsers();
}
}
}
//encryptUsers();
System.exit(2);
return usnm;
}
And here's some input/output:
Startup initiated.
Logfile exists.
Users file exists.
New user? n
ELSE
LOGIN
Username: rik
Password:
rik:55.
startUsnm: 0
endUsnm: 3
startPass: 4
endPass: -1
Usnm: rik
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: -5
at java.lang.String.substring(String.java:1949)
at client0_0_2.loginToClient(client0_0_2.java:103)
at client0_0_2.general(client0_0_2.java:209)
at client0_0_2.<init>(client0_0_2.java:221)
at client0_0_2.main(client0_0_2.java:228)
EDIT : SOLUTION FOUND!
For some reason, indexOf() does not want to find a '.'- when replaced with a hyphen('-'), however, it runs perfectly, seemingly!
I think the error is in this line:
String Pass = logdat.substring(startPass, passend);
For some reason (you'll have to determine why), you compute passend by searching for . in the string. If . isn't present, indexOf returns -1 as a sentinel. This isn't the line that causes the exception, though. I think it's the above line, since if you try to compute a substring ending at passend when passend is -1, you would get the above error.
Try determining why your string doesn't contain a . in it.
Hope this helps!
When indexOf() returns -1, it means that the value couldn't be found in the String. So, in this case, you're searching a String for '.' which doesn't exist in the String.
I would recommend that you always check the values of indexOf() after the call, and handle the -1 properly. For many cases, its probably sufficient to set it to either 0 or string.length(), depending on how you will use it later in your code.
Regardless, if you're expecting a '.' to exist and there isn't one, you'll need to debug through your code to find out what the value is, and where the '.' is missing.
indexOf() returns -1 if the specified string can't be found.
The problem is in the Line:
String Pass = logdat.substring(startPass, passend);
because of negative index.