Develop Reference

How do i print the the first initial of a string and the last word of a string?

How do I print only the first letter of the first word and the whole word of the last? for example,
I will request username input like "Enter your first and last name" and then if I type my name like "Peter Griffin", I want to print only "P and Griffin". I hope this question make sense. Please, help. I'm a complete beginner as you can tell.
Here is my code:
public static void main(String[] args) {
Scanner scan=new Scanner(System.in);
System.out.println("Enter your first and last name");
String fname=scan.next();
}

The String methods trim, substring, indexof, lastindexof, and maybe split should get you going.

This should do the work (typed directly here, so syntax errors might be there)
String fname=scan.nextLine(); // or however you would read whole line
String parts=fname.split(" ");
System.out.printf("%s %s",parts[0].substring(0,1),parts[parts.length-1]);
What you have to do next:
Check if there actually at least 2 elements in parts array
Check if first element is actually at least 1 char (no empty parts)
Check if there is actually line to read
Do your next homework yourself, otherwise you will not anything

I recommand you to watch subString(1, x) and indexOf(" ") to cut from index 1 to first space.
or here a other exemple, dealing with lower and multi name :
String s = "peter griffin foobar";
String[] splitted = s.toLowerCase().split(" ");
StringBuilder results = new StringBuilder();
results.append(String.valueOf(splitted[0].charAt(0)).toUpperCase() + " ");
for (int i = 1; i < splitted.length; i++) {
results.append(splitted[i].substring(0, 1).toUpperCase() + splitted[i].substring(1)+" ");
}
System.out.println(results.toString());

How can I obtain the first character of a string that is given by a user input in java

I want the user to input a String, lets say his or her name. The name can be Jessica or Steve. I want the program to recognize the string but only output the first three letters. It can really be any number of letters I decide I want to output (in this case 3), and yes, I have tried
charAt();
However, I do not want to hard code a string in the program, I want a user input. So it throws me an error. The code below is what I have.
public static void main(String args[]){
Scanner Name = new Scanner(System.in);
System.out.print("Insert Name here ");
System.out.print(Name.nextLine());
System.out.println();
for(int i=0; i<=2; i++){
System.out.println(Name.next(i));
}
}
the error occurs at
System.out.println(Name.next(i)); it underlines the .next area and it gives me an error that states,
"The Method next(String) in the type Scanner is not applicable for arguments (int)"
Now I know my output is supposed to be a of a string type for every iteration it should be a int, such that 0 is the first index of the string 1 should be the second and 2 should be the third index, but its a char creating a string and I get confused.

System.out.println("Enter string");
Scanner name = new Scanner(System.in);
String str= name.next();
System.out.println("Enter number of chars to be displayed");
Scanner chars = new Scanner(System.in);
int a = chars.nextInt();
System.out.println(str.substring(0, Math.min(str.length(), a)));

The char type has been essentially broken since Java 2, and legacy since Java 5. As a 16-bit value, char is physically incapable of representing most characters.
Instead, use code point integer numbers to work with individual characters.
Call String#codePoints to get an IntStream of the code point for each character.
Truncate the stream by calling limit while passing the number of characters you want.
Build a new String with resulting text by passing references to methods found on the StringBuilder class.
int limit = 3 ; // How many characters to pull from each name.
String output =
"Jessica"
.codePoints()
.limit( limit )
.collect(
StringBuilder::new,
StringBuilder::appendCodePoint,
StringBuilder::append
)
.toString()
;
Jes

When you take entry from a User it's always a good idea to validate the input to ensure it will meet the rules of your code so as not to initiate Exceptions (errors). If the entry by the User is found to be invalid then provide the opportunity for the User to enter a correct response, for example:
Scanner userInput = new Scanner(System.in);
String name = "";
// Prompt loop....
while (name.isEmpty()) {
System.out.print("Please enter Name here: --> ");
/* Get the name entry from User and trim the entry
of any possible leading or triling whitespaces. */
name = userInput.nextLine().trim();
/* Validate Entry...
If the entry is blank, just one or more whitespaces,
or is less than 3 characters in length then inform
the User of an invalid entry an to try again. */
if (name.isEmpty() || name.length() < 3) {
System.out.println("Invalid Entry (" + name + ")!\n"
+ "Name must be at least 3 characters in length!\n"
+ "Try Again...\n");
name = "";
}
}
/* If we get to this point then the entry meets our
validation rules. Now we get the first three
characters from the input name and display it. */
String shortName = name.substring(0, 3);
System.out.println();
System.out.println("Name supplied: --> " + name);
System.out.println("Short Name: --> " + shortName);
As you can see in the code above the String#substring() method is used to get the first three characters of the string (name) entered by the User.

Java input/output confusion

I am writing a program and I need to input a value for index, but the index should be composite, e.g 44GH.
My question is, how to make the program to do not crash when I ask the user to input it and then I want to display it?
I have been looking for answer in the site, but they are only for integer or string type.
If anyone can help, would be really appreciated.
Scanner s input = new Scanner(System.in);
private ArrayList<Product> productList;
System.out.println("Enter the product");
String product = s.nextLine();
System.out.println("Input code for your product e.g F7PP");
String code = s.nextLine();
}
public void deleteProduct(){
System.out.println("Enter the code of your product that you want to delete ");
String removed = input.nextLine();
if (productList.isEmpty()) {
System.out.println("There are no products for removing");
} else {
String aString = input.next();
productList.remove(aString);
}
}

Remove all non digits char before casting to integer:
String numbersOnly= aString.replaceAll("[^0-9]", "");
Integer result = Integer.parseInt(numbersOnly);

The best way to do it is to create some RegEx that could solve this problem, and you test if your input matches your RegExp. Here's a good website to test RegExp : Debuggex
Then, when you know how to extract the Integer part, you parse it.

I think the OP wants to print out a string just but correct me if I am wrong. So,
Scanner input = new Scanner(System.in);
String aString = input.nextLine(); // FFR55 or something is expected
System.out.println(aString);
Then obviously you can use:
aString.replaceAll();
Integer.parseInt();
To modify the output but from what I gather, the output is expected to be something like FFR55.

Try making the code split the two parts:
int numbers = Integer.parseInt(string.replaceAll("[^0-9]", ""));
String chars = string.replaceAll("[0-9]", "").toUpperCase();
int char0Index = ((int) chars.charAt(0)) - 65;
int char1Index = ((int) chars.charAt(1)) - 65;
This code makes a variable numbers, holding the index of the number part of the input string, as well as char0Index and char1Index, holding the value of the two characters from 0-25.
You can add the two characters, or use the characters for rows and numbers for columns, or whatever you need.

print even words from string input?

I am in a beginners course but am having difficulty with the approach for the following question: Write a program that asks the user to enter a line of input. The program should then display a line containing only the even numbered words.
For example, if the user entered
I had a dream that Jake ate a blue frog,
The output should be
had dream Jake a frog
I am not sure what method to use to solve this. I began with the following, but I know that will simply return the entire input:
import java.util.Scanner;
public class HW2Q1
{
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a sentence");
String sentence = keyboard.next();
System.out.println();
System.out.println(sentence);
}
}

I dont want to give away the answer to the question (for the test, not here), but I suggest you look into
String.Split()
From there you would need to iterate through the results and combine in another string for output. Hope that helps.

While there will be more simpler and easier way to do this, I'll use the basic structure- for loop, if block and a while loop to achieve it. I hope you will be able to crack the code. Try running it and let me know if there is an error.
String newsent;
int i;
//declare these 2 variables
sentence.trim(); //this is important as our program runs on space
for(i=0;i<sentence.length;i++) //to skip the odd words
{
if(sentence.charAt(i)=" " && sentence.charAt(i+1)!=" ") //enters when a space is encountered after every odd word
{
i++;
while(i<sentence.length && sentence.charAt(i)!=" ") //adds the even word to the string newsent letter by letter unless a space is encountered
{
newsent=newsent + sentence.charAt(i);
i++;
}
newsent=newsent+" "; //add space at the end of even word added to the newsent
}
}
System.out.println(newsent.trim());
// removes the extra space at the end and prints newsent

you should use sentence.split(regex) the regular expression is going to describe what separate your worlds , in your case it is white space (' ') so the regex is going to be like this:
regex="[ ]+";
the [ ] means that a space will separate your words the + means that it can be a single or multiple successive white space (ie one space or more)
your code might look like this
Scanner sc= new Scanner(System.in);
String line=sc.nextLine();
String[] chunks=line.split("[ ]+");
String finalresult="";
int l=chunks.length/2;
for(int i=0;i<=l;i++){
finalresult+=chunks[i*2]+" ";//means finalresult= finalresult+chunks[i*2]+" "
}
System.out.println(finalresult);

Since you said you are a beginner, I'm going to try and use simple methods.
You could use the indexOf() method to find the indices of spaces. Then, using a while loop for the length of the sentence, go through the sentence adding every even word. To determine an even word, create an integer and add 1 to it for every iteration of the while loop. Use (integer you made)%2==0 to determine whether you are on an even or odd iteration. Concatenate the word on every even iteration (using an if statement).
If you get something like Index out of range -1, manipulate the input string by adding a space to the end.
Remember to structure the loop such that, regardless of the whether it is an even or odd iteration, the counter increases by 1.
You could alternatively remove the odd words instead of concatenation the even words, but that would be more difficult.

Not sure how you want to handle things like multiple spaces between words or weird non-alphabetically characters in the entry but this should take care of the main use case:
import java.util.Scanner;
public class HW2Q1 {
public static void main(String[] args)
{
System.out.println("Enter a sentence");
// get input and convert it to a list
Scanner keyboard = new Scanner(System.in);
String sentence = keyboard.nextLine();
String[] sentenceList = sentence.split(" ");
// iterate through the list and write elements with odd indices to a String
String returnVal = new String();
for (int i = 1; i < sentenceList.length; i+=2) {
returnVal += sentenceList[i] + " ";
}
// print the string to the console, and remove trailing whitespace.
System.out.println(returnVal.trim());
}
}

Storing multiple phone numbers in a single array in Java

I'm working on a program and I'm stuck. This particular program is supposed to prompt the user to input either an uppercase or lowercase Y to process a phone number, they are then prompted to enter the character representation of a phone number (like CALL HOME would be 225-5466), this repeats until the user enters something other than the letter Y. All of the words entered are to be stored into a single array. The program is then to convert these words in the array to actual phone numbers. I'm kind of confused as to how to set this up. Here is what I have so far.
import java.util.*;
public class Program1 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String begin;
int phoneNumber = number.convertNum();
System.out.println("Please enter an uppercase or lowercase Y when you are ready to enter a telephone number: ");
begin = input.next();
while (begin.equals("y") || begin.equals("Y")) {
System.out.println("Please enter a telephone number expressed in letters: ");
String letters = input.next();
char[] phoneArray = letters.toCharArray();
System.out.println("Please enter an uppercase or lowercase Y when you are ready to enter a telephone number: ");
begin = input.next();
}
System.out.println("Here is the numeric representation of the phone number(s) you entered");
}
public static int convertNum(char[] phoneArray) {
return number;
}
}
I realize that the second method doesn't have anything to return yet, I just wanted to put that in there while I was doing things that I actually know how to do ha. The convertNum() method is supposed to be the method with which the array of characters is converted to phone numbers.
I'm still trying to think my way through this. I would think it'd be easier to store the inputs from the user as individual letters rather than words for the sake of converting to phone numbers.
Also, we are only supposed to recognize the first 7 letters of each word that is entered, like the CALL HOME example, there are 8 letters but it's still a seven digit phone number, so I'm not sure how that would work.
Also, when printing the phone numbers after they've been converted, we're supposed to print the hyphen after the third number, I have no clue how that would be done from an array.
I was actually feeling pretty good about this program until I reached this point ha. Any help would be greatly appreciated.

To translate a character to it's proper number, you can use a map, where the key is a character, and the value is the digit (in string form) that it represents.
Map<Character,String> charToPhoneDigitMap = new HashMap<Character,String>();
charToPhoneDigitMap.put('A', "2");
charToPhoneDigitMap.put('B', "2");
charToPhoneDigitMap.put('C', "2");
charToPhoneDigitMap.put('D', "3");
...
charToPhoneDigitMap.put('W', "9");
charToPhoneDigitMap.put('X', "9");
charToPhoneDigitMap.put('Y', "9");
charToPhoneDigitMap.put('Z', null);
So, for each character in the input string, ignoring any spaces and dashes, get it's digit:
String digitStr = charToPhoneDigitMap.get(inputChar);
if(digitStr == null) {
throw new IllegalArgumentException("'" + inputChar + "' has no corresponding phone number digit.");
}
phoneNumString += digitStr;
When the length of phoneNumString reaches 7, stop.
As far as displaying the dash: Don't store the dash, just store the raw digits.
Create a getPhoneNumberWithDash(raw_phoneNumStr) function, that returns it with the dash in the right place.
Now, if you also want to store the letter-representation, then you might want an array of a PhoneNumbers, instead of just a string-array containing only the raw phone numbers (seven digits each):
public class PhoneNumber {
private final String digits;
private final String letters;
public PhoneNumber(String digits, String letters) {
this.digits = digits;
this.letters = letters;
}
public String getLetters() {
return letters;
}
String getDigits() {
return digits;
}
}

A better approach to this would be to make a class called PhoneNumber for example :
public class PhoneNumber {
String name; //the representation like "Call Home"
String number;//the actual phone number like "225-5466"
//constructor ...
}
and then store create instances of PhoneNumber and store them in a List or ArrayList
public static void main(String args[]){
ArrayList<PhoneNumber> numbersList = new ArrayList();
String name;
String number;
Scanner input = new Scanner(System.in);
System.out.println("input number representation");
name=input.nextLine();
System.out.println("input number ");
number=input.nextLine();
numbersList.add(new PhoneNumber(name,number));
System.out.println(numbersList.get(0).name+" represents :"+numbersList.get(0).number);
}