For this program it asks for the user to input their full name. It then sorts out the first name and last name by separating them at the space the put between the first and last name. However, indexOf() is not recognizing the space and only returns -1. Why is that? Thanks.
Here is the prompt off of PracticeIt:
Write a method called processName that accepts a Scanner for the console as a parameter and that prompts the user to enter his or her full name, then prints the name in reverse order (i.e., last name, first name). You may assume that only a first and last name will be given. You should read the entire line of input at once with the Scanner and then break it apart as necessary. Here is a sample dialogue with the user:
Please enter your full name: Sammy Jankis
Your name in reverse order is Jankis, Sammy
import java.util.*;
public class Exercise15 {
public static void main(String[] args) {
Scanner inputScanner = new Scanner(System.in);
processName(inputScanner);
}
public static void processName(Scanner inputScanner) {
System.out.print("Please enter your full name: ");
String fullName = inputScanner.next();
int space = fullName.indexOf(" "); // always return -1 for spaces
int length = fullName.length();
String lastName = fullName.substring(space+1,length+1);
String firstname = fullName.substring(0, space);
System.out.print("Your name in reverse order is " + lastName + ", " + firstname);
}
}
As next will return the next token use nextLine not next to get the whole line
see http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#next()
When you do String fullName = inputScanner.next() you only read till the next whitespace so obviously there is no whitespace in fullName since it is only the first name.
If you want to read the whole line use String fullName = inputScanner.nextLine();
Related
So I have a file which has all presidents in it - their first name, middle initial (if any), and last name.
The file needs to be read in, and a user can enter a president's name to search for it, and that president should be displayed.
I have it displaying the president if a user searches by first name or by last name, but not by both.
For example, the external file contains:
George,Washington,(1789-1797)
Franklin,D.,Roosevelt,(1933-1945)
... and so on with all the presidents
I need the user to be able to either type in the first name, the last name, or both first and last name and get the desired result (the date is irrelevant for the most part).
Tried lots of different things, but not getting there as far as displaying the president if user searches by first and last name.
Here is what I got so far:
public class NameSearch {
public static void main(String[] args) throws IOException {
try {
// read from presidents file
Scanner presidentsFile = new Scanner(new File("Presidents.txt"));
// scanner for user input
Scanner keyboard = new Scanner(System.in);
// create array list of each line in presidents file
ArrayList<String> presidentsArrayList = new ArrayList<String>();
// prompt user to enter a string to see if it matches with a president's name
System.out.println("Enter a search string of letters to find a president match: ");
// store user input
String userInput = keyboard.nextLine();
// add president file info to array list linesInPresidentFile
while (presidentsFile.hasNextLine()) {
presidentsArrayList.add(presidentsFile.nextLine());
} // end while loop
String presidentNamesArray[] = presidentsArrayList.toArray(new String[presidentsArrayList.size()]);
String results = searchArray(presidentNamesArray, userInput);
//System.out.println("\nThe presidents who have \"" + userInput + "\" as part of their name are: ");
} catch (FileNotFoundException ex) {
// print out error (if any) to screen
System.out.println(ex.toString());
} // end catch block
} // end main
// method to search for a specific value in an array
public static String searchArray(String array[], String value) {
for (int i = 0; i < array.length; i++) {
if (array[i].toLowerCase().contains(value.toLowerCase())) {
String splitter[] = array[i].split(" ,");
System.out.println(Arrays.toString(splitter));
}
}
return Arrays.toString(array);
}
}
There is another way in which I might have implemented this.Read the file inputs and stored them as objects (class with lname, fname and year perhaps). In this way you can search for lname from user input, match it up with its corresponding fname (as same objects). The creation can be done once and searching can be done in a while loop implementing users consent of continuing the search.
//define your class like this:
static int i; //to keep a track of number of objects
public class dummy{
string fname;
string lname;
string year;
};
while the file content exists:
read the line
dummy dobj[i++] = new dummy();//allocate memory for the object
split the different parameters (fname, lname, year) from the read line
put these read parameters into the object
dobj[i].fname = first;
dobj[i].lname = second;
dobj[i].year = y;
//ask your user to enter the query in a specified format
//if he enters lname, compare your input to all the object's lname, and so on
//in case of lname && fname, compare your input to the lname first and then check for the corresponding objects fname, if they match.. display
Actually, there are many ways in which you can achieve what you wish to program. You can ask use the array list indices to solve it. If you take in the input from the user in a particular format, you can map it to the index in that list. Further, if you want to use first name and last name together, you may use these index representing the first and last name to come from same list.
The reason you may have problems searching by both first and last names is because you have to match your input exactly (ignoring case of course). What I mean is if you use George Washington as input, your program will not find a match for the George,Washington,(1789-1797) line. This is because your program treats George Washington as one string. Note: the input is missing the comma, so it will not be considered a substring of George,Washington,(1789-1797). If you used George,Washington as your input string, then your program would print the George Washington line. Your program just searches if the input string is a substring of any of the lines in your file. It does not search for a first name or last name specifically. If you used in as your input string, then you would get a match for both George Washington and Franklin D. Roosevelt.What you could do is take your input data and split it and search for each of the terms. You can either accept lines that match all of the terms provided, or at least one of the terms provided.
public static String searchArray(String array[], String value) {
// Uses both blank spaces and commas as delimiters
String[] terms = value.toLowerCase().Split("[ ,]");
for (int i = 0; i < array.length; i++) {
String line = array[i].toLowerCase();
boolean printIfAllMatch = true;
boolean printIfAtLeastOneMatches = false;
for(int j = 0 ; j < terms.length; j++) {
// Check that all terms are contained in the line
printIfAllMatch &= line.Contains(terms[j]);
// Check that at least one term is in the line
printIfAtLeastOneMatches |= line.Contains(terms[j]);
}
String splitter[] = array[i].split(" ,");
if (printIfAllMatch) {
System.out.println(Arrays.toString(splitter));
}
if(printIfAtLeastOneMatches) {
System.out.println(Arrays.toString(splitter));
}
}
//I'm not sure why you're returning the original array as a string
//I would think it would make more sense to return an Array of filtered data.
return Arrays.toString(array);
}
This does not take name ordering into account. If that's what you're going for, then I would suggest making a class and parsing each line in the file as an new object and trying to match the first term provided with the first name and second term provided with the last name, or something to that effect.
For my project I need to input a first and last name with no numbers but I simply can't find anything online. If you could help, that would be terrific.
Also if you have the time, I need to flip the first and last name with a comma when the user inputs them.
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
public class PhoneListr {
public static void main (String[] args) throws IOException {
String firstName;
String lastName;
System.out.println ("Please enter your first name:");
firstName = PhoneList ("");
System.out.println ("Please enter your last name:");
lastName = PhoneList ("");
System.out.println ("Your full name is: " + lastName + "," + firstName);
}
public static String PhoneList (String input) throws IOException {
boolean continueInput = false;
while (continueInput == false) {
BufferedReader bufferedReader = new BufferedReader (new InputStreamReader (System.in));
input = bufferedReader.readLine();
continueInput = true;
if(input.matches("[a-zA-Z]+")) {
continueInput = true;
}
else {
System.out.println ("Error, you may only use the alphabet");
continueInput = false;
}
}
return input;
}
}
use String.matches(regex):
if(input.matches("[a-zA-Z]+")) {
System.out.println("your input contains no numerics");
}
else {
System.out.println("only alphabets allowed");
}
the above regex checks a through z, or A through Z, inclusive (range).
For this type of string matching you need to use Regular Expressions, or "RegEx"es. It is a very big topic to cover but here's an introduction. RegExes are tools used to test whether strings match certain criteria, and/or to pull certain patterns out of that string or replace certain parts that match those patterns with something else.
Here is an example using a RegEx to test whether your input contains a digit:
if(input.matches("\\d")) {
// matched a digit, do something
}
Based on OP problem and clarification here are few suggestions.
Chaitanya solution handles the check for only alphabets perfectly.
About the neglected areas of problem :
i would advice you to make two variable firstName and lastName inside the main()
String firstName;
String lastName;
Change retun type of method phoneList() to String
return the entered name input insted of number inside the method phoneList ( dont actually see why you are returning number) and store it inside the firstName and lastName
System.out.println ("Please enter your first name:");
firstName = PhoneList (0);
System.out.println ("Please input your last name:");
lastNamr =PhoneList (0);
now to print it in the "comma format" use
System.out.println("full name is: " +lastName+ "," +firstName);
As i read your program again , its a mess!!
About the method phoneList()
Use regex condition to set continueInput to true/flase and not exploit execptions.
P.s. I would appreciate "editing" to post , if any fellow member find any mistakes above, using a mobile, not sure about formatting etc. Thanks. :-) (y)
You can also use
if(input.matches("[^0-9]"))
{
System.out.println("Don't input numbers!");
continueInput = false;}
Can't understand what 2nd question asks. For answer what I get from your 2nd question is like this.
In main function change the code like this
String first_name = null;
String last_name = null;
System.out.println ("Please enter your first name:");
first_name = PhoneList();
System.out.println ("Please input your last name:");
second_name = PhoneList();
System.out.println (second_name+","+first_name);
then in PhoneList function last line should be changed to
return input;
Please check for a link! for more info
You can add a check by passing the argument to method StringUtils.isNumeric
This returns true if the String entered is numeric
I'm stuck and need your help (yes, it's homework), what I'm trying to do is get my code to read the contents in the text file and output the words by specific words. For example I want it to output all words that start with letter "g".
Here's a pseudocode code if I didn't explain that well:
BEGIN
Get the initial letter from the user
While there are more entries in the file
Get the next personal name
Get the next surname
Get the next year info
If the surname starts with the initial letter
Output the person name, surname and year info
End while
END
So far I've managed to get this done, and now I'm stuck where you output the names correctly. Any help or tutorials will be appreciated.
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
public class PrimeMinisters
{
public static void main(String[] args) throws FileNotFoundException
{
// ask the user for the first letter
Scanner keyboard = new Scanner(System.in);
System.out.print("What is the first letter? ");
String input = keyboard.next().toLowerCase();
char firstLetter = input.charAt(0);
// open the data file
File pmFile = new File ("OZPMS.txt");
// create a scanner from the file
Scanner pmInput = new Scanner (pmFile);
// read one line of data at a time, processing each line
while(pmInput.hasNext())
{
String names = pmInput.next();
System.out.println(names);
}
// be polite and close the file
pmInput.close();
}
}
I'd recommend using nextLine() over next(). From this you would then use the String's startsWith(String stringsequence) method which returns a boolean to get all the values beginning with the letter of your choice:
while(pmInput.hasNextLine())
{
String names = pmInput.nextLine();
System.out.println(names);
if(names.startsWith("g")) {
//the name begins with letter g do whatever
}
}
You can have a look at more methods for String here: http://docs.oracle.com/javase/7/docs/api/java/lang/String.html
Since your requirements state to look at the surname's first letter, it will be easier to tokenize each line while you read it (while checking to see if the user input is the first letter of the surname). Assuming that the line is in the order that you stated above, the surname will be token #2 (index 1 of the array).
public class PrimeMinisters
{
public static void main(String[] args) throws FileNotFoundException
{
// ask the user for the first letter
Scanner keyboard = new Scanner(System.in);
System.out.print("What is the first letter? ");
String input = keyboard.next().toLowerCase();
char firstLetter = input.charAt(0);
// open the data file
File pmFile = new File ("OZPMS.txt");
// create a scanner from the file
Scanner pmInput = new Scanner (pmFile);
// read one line of data at a time, processing each line
while(pmInput.hasNextLine())
{
String names = pmInput.nextLine();
// Break line into tokens. This is assuming that there are only
// 3 strings per line in the following order (personal name, surname, yearinfo)
//
String[] info = names.split("\\s");
// Check 2nd string in line (since you are looking for the first character in
// the surname and not the personal name.
//
if(info[1].startsWith(input))
{
System.out.println(info[0] + "\t" + info[1] + "\t" + info[2]);
}
}
// be polite and close the file
pmInput.close();
}
}
I have just started the java programming and at the moment I am doing the basic things. I came across a problem that I can't solve and didn't found any answers around so I thought you might give me a hand. I want to write a program to prompt the user to enter their full name (first name, second name and surname) and output their initials.
Assuming that the user always types three names and does not include any unnecessary spaces. So the input data will always look like this : Name Middlename Surname
Some of my code that I have done and stuck in there as I get number of the letter that is in the code instead of letter itself.
import java.util.*;
public class Initials
{
public static void main (String[] args)
{
//create Scanner to read in data
Scanner myKeyboard = new Scanner(System.in);
//prompt user for input – use print to leave cursor on line
System.out.print("Please enter Your full Name , Middle name And Surname: ");
String name = myKeyboard.nextLine();
String initials1 = name.substring(0, 1);
int initials2 = name.
//output Initials
System.out.println ("Initials Are " + initials1 + initials2 + initials3);
}
}
Users will enter a string like
"first middle last"
so therefore you need to get each word from the string.
Loot at split.
After you get each word of the user-entered data, you need to use a loop to get the first letter of each part of the name.
First, the nextLine Function will return the full name. First, you need to .split() the string name on a space, perhaps. This requires a correctly formatted string from the user, but I wouldn't worry about that yet.
Once you split the string, it returns an array of strings. If the user put them in correectly, you can do a for loop on the array.
StringBuilder builder = new StringBuilder(3);
for(int i = 0; i < splitStringArray.length; i++)
{
builder.append(splitStringArray[i].substring(0,1));
}
System.out.println("Initials Are " + builder.toString());
Use the String split() method. This allows you to split a String using a certain regex (for example, spliting a String by the space character). The returned value is an array holding each of the split values. See the documentation for the method.
Scanner myKeyboard = new Scanner(System.in);
System.out.print("Please enter Your full Name , Middle name And Surname: ");
String name = myKeyboard.nextLine();
String[] nameParts = name.split(" ");
char firstInitial = nameParts[0].charAt(0);
char middleInitial = nameParts[1].charAt(0);
char lastInitial = nameParts[2].charAt(0);
System.out.println ("Initials Are " + firstInitial + middleInitial + lastInitial);
Note that the above assumes the user has entered the right number of names. You'll need to do some catching or checking if you need to safeguard against the users doing "weird" things.
I am trying to replace a specific character '8' with a '2' in a string. I think I have everything set up correctly and when I look online for examples, this looks like it should. When I print the string though, it is just as I entered it. To run it, test it with "80802" or some similar input. Thanks!
import java.util.Scanner;
class PhoneNumber {
public static void main(String[] args) {
String number = null;
Scanner scan = new Scanner(System.in);
// Prompt the user for a telephone number
System.out.print("Enter your telephone number: ");
// Input the user's name
number = scan.nextLine();
// Replace the relevant letters with numbers
number.replace('8', '2');
System.out.println("Your number is: " + number );
}
}
A common mistake... You want:
number = number.replace('8', '2');
String.replace() doesn't change the String, because Strings are immutable (they can not be changed). Instead, such methods return a new String with the calculated value.
number.replace() returns a new string. It does not change `number'.
number.replace('8','2'); returns the correct string it does not modify number. To get your desired functionality you must type
number = number.replace('8','2');
public static void main(String[] args) {
String number = null;
Scanner scan = new Scanner(System.in);
// Prompt the user for a telephone number
System.out.print("Enter your telephone number: ");
// Input the user's name
number = scan.nextLine();
// Replace the relevant letters with numbers
number = number.replace('8', '2');
System.out.println("Your number is: " + number );
}
Hope this helps.