Reading Input With Scanner And Checking If User Entered Empty String?
Apr 7, 2015
The project is a program that allows the user to enter students and enter grades for each student. One of the requirements is that if there is already a grade stored for the student that it will display the previous grade. IF the user then enters a new grade the new grade will be stored. IF the user simply presses enter (enters an empty string) nothing is done. I have everything working except for the requirement of doing nothing if the user enters an empty string. If I just press enter at this point I get a NumberFormatException.
The below code is a method "setTestGrades" from the student class. This method iterates through each student object stored in an array list and then checks if there is a previous grade (Requirement# unset grades have to default to -1) before allowing the user to set a new grade.
public void setTestGrades(int testNumber) { //Sets the grade for the specified test number for each student in the arraylist.
testNumber -= 1;
Scanner input = new Scanner(System.in);
for (int i = 0; i < studentList.size(); i++) {
System.out.println("Please enter the grade for Test #" + (testNumber + 1) + " For Student " + studentList.get(i).getStudentName());
I have the code below that just keeps getting the user's name and displaying it until the user enter's an empty string. Well, to simulate that, I just hit the keyboard instead of entering any name but for some reasons I am not seeing in my code, the programme just keeps looping.
System.out.println("Enter your name : "); Scanner st = new Scanner(System.in); while(st.hasNext()){ System.out.println("Enter your name : "); String name = st.nextLine(); System.out.println(name); if(name==" ") break; } System.out.println("you are out of the while loop now!!");
I made a guess a number program but I am having issue figuring out a way that when a user enter's in nothing for the program to spit out a message saying "hey entering nothing doesn't work try again" then ask for input. I have done some research and from what I have found is to read the input in as a String rather than int, and use something like Integer.valueOf() to get the integer value but I am completely lost on how to apply that to my program here is my code
//import statements import java.util.*; //for scanner class // class beginning public class Guess { public static void main(String[] args ) { //Declare variables area int guess, secretNumber = (int) (Math.random() * 10 + 1), lowGuess,highGuess;
I just can't find a way to check if user puts any input or not? The line is Employee Name and I need to validate that he puts something there.
import java.util.Scanner; public class JavaMartInventorySystem { public static void main(String[] args) { String empName; Scanner keyboard = new Scanner(System.in);
So I clipped this out of my Jeopardy game code and made it into its own project for testing. using this code I want to check to see if the input for wage is an integer?
import java.util.Scanner; public class test { /** * @param args */ public static void main(String[] args) { Scanner input = new Scanner (System.in);
Obviously right now if you enter "aflwkj" or some such for the wager, the program terminates. How to make a loop that will keep asking the user for a value for wage until the input is an integer?
Logic her eis when user selects option1, it asks for user to enter name and as soon as user enters name, it should compar name to existing names in txt file. I have user while loop and for loop but for some reason, it doesnt compare properly as there seems to be some mistake in looping and it just read first line or you can say single line rather than comparing it with all lines in txt file. i have attached votes.txt file with this. Also, if user doesnt exists infile, it will ask user to enter vote as yes or no and add it to file and then count total number of Yes and No votes from file and compare them.
my votes.txt file looks as below with two columns namely (name and vote).
Hiren No samir yes bob no rikul no master yes patrick no summer yes bhanja no
I've been trying to get my program to not accept empty strings when the user inputs, but I'm having some difficulties. I've tried for loops, as well as while loops.
import java.util.Scanner; public class GasMileage { /** * displayIntro * This method displays the introduction to the user */ public static void displayIntro()
The code for my button is below - I know it is wrong and that I need to change line 8 at least,so I am technically asking the property object if there is a key_name there but I dont quite get how to do that
//code for button
JButton btnSearch = new JButton("Search"); btnSearch.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { //find selected command String key_name = textFieldSearch.getText();
[Code] ....
I basically just want the user typed in word to be checked against a keyword in a properties file and if it exists, pull the key and the value back into a panel
I am trying to do is get a user to input their name into the system. Once the user has inputted the name into the system, the system should check to see if the name entered matches "alice". If this is true then the system should print "welcome to the system alice". If it is not alice it should not do anything.
Here is the code I have so far... The fault/ error seems to be with the sInput string in the IF statement.
import java.io.*; public class Hellohuman { public static void main (String[] args) { try { InputStreamReader isr = new InputStreamReader(System.in);
/* * To change this template, choose Tools | Templates * and open the template in the editor. */
package firstgui; import javax.swing.*; import java.awt.event.*; public class TicTacToe {
[Code] ......
Program is 10x10 board, I need to check if the user's input is a duplicate of any number in that same column, but I can't figure it out. When I tried it, it always check the same box. For example, if I entered 4 in [1][1] (going by 10x10 grid), it automatically checks right after I entered that [1][1] is the same as my input and erases it. My professor wants me to check it with the "CheckWinner" method.
I tried the following when someone told me to pass the reference of the JButton being clicked to ignore it.
Assignment: Your task is to implement a similar scheme to store polynomials of any number of terms, such that the number of terms and the components (coefficient, variable and exponent) of every term are entered from the keyboard. To implement the interactive input we will using the Java class Scanner, defined in the java.utils standard package. The Scanner class can be used in Java to read data types from a file.
Since the input console (keyboard) is treated as the file called System.in, we can create a Scanner for that input stream as new Scanner (System.in), as shown below. Once you define a Scanner object, using its method next() you can read Strings from the file/keyboard. The incomplete program below is your assignment. You are supposed to complete without changing the existing code. Your output should be the terms of the polynomial entered by the user, separated by + signs. Additional instructions in the code below, that you will change to achieve the requested functionality.
import java.util.Scanner; public class Polynomials { public static void storeTerm (int coeff, String var, int exp, String poly[][], int where){ //ENTER THE COEFFICIENT, VARIABLE AND EXPONENT INTO THE //ARRAY POLY THAT REPRESENTS THE POLYNOMIAL, AT POSITION "where" //THAT RANGES BETWEEN INDEX 0 AND POLY.LENGTH-1
[Code] ....
Anyways, I'm not looking for straight answers. I just want to know which section I should start on first because I was advised to tackle programs one problem at a time.
The method below is called within a large loop in another method. The code has been boiled down to easily show the problem I'm having. I found that the method worked fine (prompts user for input, gets input, returns input) until I added a statement at the end of the method that closes the Scanner object. When the kb.close() statement is present, the method works the first time through, but subsequent calls to this method only display the prompt and the Scanner object never waits for the user to input anything thereafter.
public int scanIt() { int i; Scanner kb = new Scanner(System.out); System.out.print("==> "); // prompt for input if(kb.hasNextInt()) { i = kb.nextInt(); System.out.println("User entered " + i); } kb.close(); }
I am having issues with the program below everything works but I can't figure out a way to add code that if a user just hits enter without inputting anything it says "entering in nothing is not a valid choice" I am stuck on how to compare a int to a string ...
//import statements import java.util.*; //for scanner class // class beginning public class Guess { public static void main(String[] args ) { //Declare variables area
I'm having trouble with the last few lines of the code. It's supposed to take a replacement string entered by the user and print out the new string. For some reason it's now allowing me to enter a replacement string
import java.util.Scanner; public class Project02 { public static void main(String[] args) { Scanner keyboard = new Scanner(System.in); System.out.print("Enter a long string: "); String lString = keyboard.nextLine();
[Code] ....
Output:
Enter a long string: the quick brown fox jumped over the lazy dog Enter a substring: jumped Length of your string: 44 Length of your substring: 6 Starting position of your substring in string: 20 String before your substring: the quick brown fox String after your substring: over the lazy dog Enter a position between 0 and 43: 18 The character at position 18 is x
Enter a replacement string: Your new string is: the quick brown fox over the lazy dog <------ isn't taking user input
I have returned with yet another problem but I think this one might be a bit easier to fix.
So the whole MO of this program is to take user input, and display the sum of the digits of the number they entered. I am supposed to do this by utilizing methods. So far this is what I have and when I compile it tells me that it "cannot find symbol", which I don't understand as I define what "m" is in the for loop. The other error is that it says:
"Exercise6_2.java:22: error: incompatible types: possible lossy conversion from long to int return result; ^
I don't understand why it's giving me this error nor do I understand why result seems to inherently be an int. (Also the public static int sumDigits(long n) method was given to me by the book so that is what I am supposed to use).
import java.util.Scanner; public class Exercise6_2 { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("Enter a integer"); long n = input.nextLong();
I'm having an issue, I have a scanner (Scan.nextLine();) that scans the console for input to fetch the string "word". Then I want to fetch a character using Scan.findInLine(word).charAt(number);. The problem is that the console requires me to write 2 lines in order for the program to move on. I only want the program to scan for a word, and then move on with what it has instead of requiring 2 inputs.
I am using jdk 6 ... I came to know that how we can read strings from user input ... and how we can convert a string to int .. but i dont fount how to read a character by character from user ..
I am required to read user input to create two matrices which will eventually be added together. I am unsure as to how I can read the input from the user as an int and not a String. The input is from size 0-10 for both column and row size. Also, can you have a new button created in the actionPerformed method of a previous button?
import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.util.*; public class Matrices implements ActionListener { private JFrame win1, win2, win3, win4;
I trying to get this code to get user input instead of reading from a hardcoded array. I'm getting compile errors while trying to get user input. Here's some of the code:
Basically I need to make a program prompts the user for an integer, check to make sure the length entered by the user is a power of 2 and at least 2. Then I need to convert from base e to base 2 then I need to print the tick marks of a ruler based of the value of the length.
I got the whole converting thing working and the check for a power of 2, that wasn't an issue because it didn't require any recursion. I just don't know how to print out the proper tick mark values.
The way it is supposed to work is that it needs to look like this. Say the user enters 8;
012131210 012345678
Or if the user enters 16;
01213121412131210 01234567890123456
The bottom row is pretty much just the index value, that I print fine.
The top row though is supposed to be the length of the ticks on a ruler, with the middle most value being the value of the conversion from base e to base 2 from above. I can get that printed and what I get just looks like this.
For 8;
000030000 012345678
For 16;
00000000400000000 01234567890123456
As you can see I can get the middle value and the index values below but I don't know how to use recursion to get the right numbers.
Here's my current code.
import java.util.*; public class TickMarks { public static void main (String args[]){ Scanner input = new Scanner(System.in); boolean looping = true; while(looping == true){ System.out.print("Please enter a length: ");
[Code]...
Now the methods isPowerOfTwo() and printLength() both work fine. However, I'm not sure how to get the left and right side working.
My thoughts were to split the length in half and get a left and right side. I gave both of them arrays so I can keep track of the values. Now as you've seen above I get all zeros and I know it's because that's the default value in an array, I just don't know how to get the proper values.
I have to take a users input. The general gist of the problem is I want to convert a decimal number entered by the user inputs into it's binary equivalent....the conversion part I know how to do.
I'm stuck at the user input phase. If the user inputs a decimal number within the correct range (lets say between 0-5000 for this example) the conversion goes ahead as planned and the program outputs on the screen the binary equivalent.
If on the other hand the user inputs a number outside of this range ... OR a String OR and empty space, an error message is given and the user is asked to try again. I don't know how to handle it if the user enters the different types...int or String.
I have a code that imports a text file [URL] .... and has a variety of methods for sorting through it. The file is structured differently when loaded into the environment, as each line begins with a movie and lists all of its actors. Each line has a movie title, then its release date in parentheses, and then the actors in the movie all listed and separated by slashes (Ex: /lastname 1, firstname 1/lastname 2, firstname 2/etc.....
Well I tried to create a method to search all the actors in the file for an inputted word and return the ones that have that word somewhere in their names. I managed to get it to work, but the code only runs for one line of it. How should I get this to do what its doing, but for EVERY line?
I'm having an issue with my program that needs 2 lines of input when I only want one. First I call Scan.nextLine(); to fetch a word. Then I want Scan.findInLine(word).charAt(number); to scan the string word for a letter instead of having to put another line in the console. How do I make Scan.findInLine(word).charAt(number); scan a single String instead of scanning input typed by the user?
I am having trouble with getting a user input once they enter it in to a JTextArea and then storing it in to a string value. See, I wanted the user to enter an answer in to the JTextArea, and then once I store it in to a string value, I would be able to use it later. I wanted to after storing the variable to print it on to a JLabel, but nothing is showing up... Heres my code.
static String usera[]= new String [10]; for (int i=0; i< usera.length; i++) { //These are the JTextArea names usera[0]= Question1.getText(); usera[1]= Question2.getText();
[Code].....
I already initialized the JLabels earlier in my code, and I did not feel the need to post all my code here. This is where I am trying to get the string variable and then printing it out.
So this application gets input from the user and converts it into a string. It then uses various methods to set instance variables of this class and ends up printing those classes to display information to the user about that products.
package javaapplication5; import java.text.NumberFormat; import java.util.Scanner; public class Product { private String product; private String description; private double price;
[Code] ....
I am getting a logical error. My output is this:
Enter a product for information. Choose either Java or C++ java Prduct: null Description: null Price 0.0
