I am trying to have the user set the name for how many numbers they set. for example if they set 3 the program asks for name 3 times and then sets those names to a different varible inside an array.
public static void main(String[] args) {
Scanner Num = new Scanner(System.in);
Scanner Name = new Scanner(System.in);
System.out.println("How many names do you want to enter: ");
int number = Num.nextInt();
int[] numbs = new int[number];
for (int i = 0; i < numbs.length; i++) {
System.out.println("What is your name");
String [] nameArray = Name.nextLine();
Just a small improvement over Titan's answer.
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("How many names do you want to enter: ");
int numberOfTimes = sc.nextInt();
String[] names = new String[numberOfTimes];
sc.nextLine();
for (int i = 0; i < numberOfTimes; i++) {
System.out.println("What is your name");
names[i] = sc.nextLine();
}
System.out.println(Arrays.toString(names));
}
Starting point
Here are several things happening in your posted code:
You have two different Scanners, each reading from System.in
After prompting for user input (int number = Num.nextInt()), you're using that number to create an array of size "number"
When you call nextLine(), you are assigning the result to a string array (String []).
Working solution
Here's a variation which addresses those issues, with a few additions, too:
Use one Scanner, and give it a general name ("scanner", not "Num") since a scanner has nothing to do with one specific data type. Any scanner can read strings, integers, booleans, bytes, etc. Look in Javadoc for the full set of supported data types.
Check if user input is valid before trying to create an array – if user enters "-1" that's a valid integer value, but not valid for allocating an array – new int[-1]) would throw a java.lang.NegativeArraySizeException at runtime.
Use "next()" instead of "nextLine()" – with the rest of your example, using "nextLine()" results in skipping one line without direct interaction from the user (so the first "name" is always an empty string)
Assign the result of "next()" to a String (not String[]), matching the return type from the method
Use "System.out.print()" instead of "println()", a little tidier program output
Use lowercase names to follow Java naming conventions ("scanner", not "Scanner")
Scanner scanner = new Scanner(System.in);
System.out.print("How many names do you want to enter: ");
int times = scanner.nextInt();
if (times < 0) {
System.out.println("negative numbers not allowed");
} else {
String[] names = new String[times];
for (int i = 0; i < times; i++) {
System.out.print("What is your name: ");
names[i] = scanner.next();
}
System.out.println(Arrays.toString(names));
}
And here's a sample run:
How many names do you want to enter: 3
What is your name: one
What is your name: two
What is your name: three
[one, two, three]
Create a String array of number length outside the loop and initialize each index with name as input.
By the way you only need to create one Scanner object for input(Not needed to create various objects for different input).
Edit - There was no use of numbs array.
Scanner sc=new Scanner(System.in);
System.out.println("How many names do you want to enter: ");
int number = sc.nextInt();
String []nameArray=new String[number];
/*Since nextInt() does not read the newline character in your input
created by hitting "Enter"*/.
sc.nextLine();
for (int i = 0; i < number; i++) {
System.out.println("What is your name");
nameArray[i]=sc.nextLine();
}
sc.close(); //To prevent memory leak
Related
I need to use scanner to get 2 inputs.
1st input is a sequence of integers that I need to store in ArrayList.
2nd input should go right after the first one and it's integer as well.
My question is - how do I stop accepting input for ArrayList and tell the machine to ask for a second number.
I ended with something like this but it does not of course work because it just keeps asking for integers for arraylist. And yes, I need to use ArrayList for the task, since I don't know how many integers there will be. I also haven't learned List interface yet so I need to use what I have in my disposal.
while (scanner.hasNextInt()) {
numbers.add(scanner.nextLine());
if (scanner.hasNextInt()) {
referenceNumber = scanner.nextInt();
}
}
I managed to solve it this way, though probably not optimal
String inputString = scanner.nextLine();
String[] inputArray = inputString.split(" ");
int[] numberArray = new int[inputArray.length];
for (int i = 0; i < inputArray.length; i++) {
numberArray[i] = Integer.parseInt(inputArray[i]);
}
if (scanner.hasNextInt()) {
referenceNumber = scanner.nextInt();
}
if your input sequence is something like 23 34 54 46 then you can use this
Scanner scanner = new Scanner(System.in);
String integers = scanner.nextLine();
StringTokenizer string = new StringTokenizer(integers);
ArrayList<Integer> list = new ArrayList<Integer>();
while(string.hasNextToken()){
list.add(Integer.parseInt(string.nextToken()));
}
This is just some homework but I cannot find a way to achieve it like I want. Have a look at my code please.
Once the numbers are typed, I'd just like to play around with them.
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
//user says if he'd like to use 3 numbers for instance (2,4,5)
System.out.println("How many numbers would you like to use? : ");
int amountOfNumbers = sc.nextInt();
System.out.println("Great! Please type in your numbers: ");
int numbers =sc.nextInt(amountOfNumbers);
// should let him write the amount of numbers he entered
}
Once he has typed the amount of numbers he'd like to use, I would like the scanner to give him the possibility to type in all of those numbers.
Let's say he the amount of numbers he'd like to use is three.
I would like him to be able to type it in the console like this:
First number + enter key
Second number + enter key
Third number + enter key
Not able to write anymore
That is what I meant here by adding "amountOfNumbers" in the scanner itself... (which is not working)
int numbers =sc.nextInt(amountOfNumbers);
BR
Consider a for loop:
for(int i = 0; i < amountofNumbers; i++){
// add to a collection / array / list
}
And then access what you need from there.
import java.util.*;
class EnterNumber{
public void enter_list_function(){
Scanner sc = new Scanner(System.in);
System.out.println("How many numbers would you like to use?");
//Enter the Numbers of amount
int input = sc.nextInt();
ArrayList<Integer> list = new ArrayList<Integer>();
System.out.println("Great! Please type in your numbers: ");
//Input - Numbers of amount
for(int j =1; j<=input; j++ ){
int addval = sc.nextInt();
//Add the enter amount in array
list.add(addval);
}
Iterator itr=list.iterator();
while(itr.hasNext()){
//get the enter amount from list
System.out.println(itr.next());
}
}
public static void main(String[] args){
EnterNumber EnterNumber = new EnterNumber();
EnterNumber.enter_list_function();
}
}
I have a For Loop and it's asking the user how many times the loop should be looped inside the loop. How do I loop it the number of times given without repeating the question "how many names would you like to input"?
The issue is that I don't want to repeat the question after the user answered it. When the user answers the question, I want it to ask for the names x amount of times and then move on.
The main problem is that I need to ask how many times to loop it after the name is asked. It's says it the assignment sheet.
Thanks so much!
for (int i = 0; i < num; i++) {
System.out.println("Enter name #" + (i+1));
names[i] = input.next();
System.out.println("How many names would you like to input?");
num = input.nextInt;
}
You must move your num getter code outside of loop like this:
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("How many names would you like to input?");
int num = input.nextInt();
String names[] = new String[num];
for (int i = 0; i < num; i++) {
System.out.println("Enter name #" + (i+1));
names[i] = input.next();
}
}
Always move these kinds of questions out of the loop rather than inside.
System.out.println("How many names would you like to input?");
num = input.next();
for (int i = 0; i < num; i++) {
System.out.println("Enter name #" + (i+1));
names[i] = input.next();
}
num = input.next();
You are asking a numbers not a string should change the .next() to either nextInt or nextShort.
#DevilsHnd the first code won't work indeed, I never saw that String [] = new String [] use array before plus this will explain better why.
#J.A.P link with code may work
import java.util.Scanner;
public class Newpro{
public static void main(String args[]){
Scanner sc = new Scanner(System.in);
System.out.println("how many times you want to loop?")
int num = sc.nextInt();//input the no of times you want to loop
String names[i] = new String[num];//initialize a string array for reading names
for(i=0;i<num;i++){
System.out.println("enter name#"+(i+1));
names[i]=sc.next();
}
for(j=0;j<num;j++){
//printing the names entered by you
System.out.println("the entered names by you are"+" "+names[j]);
}
as others suggested, you have to move your 'num' getter part out of the loop and after that initialize a string array for reading your names by specifying how many names you want to enter(index of string array = number of names you want to enter and no of times you want to loop as well==>'num') and based on that number the looping will be done with above code.
finally iterate through the array and print the names entered by you.
Edit:1
check with the below code if you need to ask "how many names user wants to input AFTER it asks for a first name.
import java.util.Scanner;
public class Newpro2{
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
//make sure you create a string array with index = no of names you want to
//enter
String[] names = new String[10];
System.out.println("enter name#1");
names[0]= sc.next();
System.out.println("how many inputs you want to give?");
num=sc.nextInt();//give the no of inputs you want to give here
//read the remaining names
for(int i=1;i<num;i++){
System.out.println("enter name#"+(i+1));
names[i] = sc.next();
}
//print all the names entered by you
for(int j=0;j<num;j++){
System.out.println("entered name#"+(j+1)+"by you is"+" "+names[j]);
}
I'm trying to create a program that takes the user's input and then scans the user's input into an array with a for loop. That way I can loop through the array to find if the string is a word palindrome or not. A word palindrome differs from a palindrome in that it is the whole word in reverse rather than each individual letter in reverse. When the program that I wrote prints it just prints null, which I believe means that it's not storing what the scanner scanned.
Below is what I've written:
String userInput, scannedWord;
Scanner keyboard = new Scanner(System.in); //scanner for user input
System.out.print("Please enter a sentence: ");
userInput = keyboard.nextLine(); //stores user input
Scanner stringScan = new Scanner(userInput); //scanner to scan through user input
int userInputLength = userInput.length(); //to find word count
int wordCount = 0; //for array size
for (int i = 0; i < userInputLength; i++) //finds word count
{
while(stringScan.hasNext())
{
scannedWord = stringScan.next();
wordCount = wordCount + 1;
}
}
String stringArray[] = new String[wordCount];
for (int i = 0; i < userInputLength; i++) //should store scanned words into the array
{
while (stringScan.hasNext())
{
scannedWord = stringScan.next();
stringArray[i] = scannedWord;
}
}
System.out.println(Arrays.toString(stringArray)); //how I've checked if it's storing
You've got some funky logic going on here. A few things:
userInput = keyboard.nextLine(); //stores user input
int userInputLength = userInput.length(); //to find word count
userInputLength is the length of the userInput string, which is the number of characters in the string, not the number of words.
It looks like the while loop is used simply to calculate the required size of the array, but the outer for loop is not required. You're effectively saying, for every character in the input string, while the scanner has another word, count the word, which doesn't make much sense.
You do something similar in your second for loop, which also doesn't make much sense.
for (int i = 0; i < userInputLength; i++) //finds word count
{
while(stringScan.hasNext())
{
scannedWord = stringScan.next();
wordCount = wordCount + 1;
}
}
It would be easier to use a List and save yourself the trouble that comes with fixed size arrays. You can just initialize the list and add things to it without caring about how big it is.
List<String> words = new ArrayList<String>();
words.add(word1);
words.add(word2);
Here's some code to simplify your problem a little:
Scanner keyboard = new Scanner(System.in); //scanner for user input
System.out.print("Please enter a sentence: ");
String userInput = keyboard.nextLine(); //stores user input
Scanner stringScan = new Scanner(userInput); //scanner to scan through user input
List<String> words = new ArrayList<String>();
while (stringScan.hasNext())
{
String scannedWord = stringScan.next();
words.add(scannedWord);
}
System.out.print(Arrays.toString(words.toArray())); // nasty! but you can see what's in the array for debugging
I have a bit of a unique problem to solve and I'm stuck.
I need to design a program that does the following:
Inputs two series of numbers (integers) from the user.
Creates two lists based on each series.
The length of each list must be determined by the value of the first digit of each series.
The rest of the digits of each series of numbers becomes the contents of the list.
Where I'm getting stuck is in trying to isolate the first number of the series to use it to determine the length of the list.
I tried something here so let me know if this is what you're looking for. It would be better for you to provide your attempt first.
I also want to point out that Lists are for the most part dynamic. You don't have to worry about the size of them like a normal array.
Scanner sc = new Scanner(System.in);
ArrayList<Integer[]> addIt = new ArrayList<>();
boolean choice = false;
while(choice == false){
String line = sc.nextLine();
if(line.equalsIgnoreCase("n")){
break;
}
else{
String[] splitArr = line.split("\\s+");
Integer[] convertedArr = new Integer[splitArr.length];
for(int i = 0; i < convertedArr.length; i++){
convertedArr[i] = Integer.parseInt(splitArr[i]);
}
addIt.add(convertedArr);
}
}
This is assuming that you are separating each integer with a whitespace. If you are separating the numbers with something else just modify the split statement.
The user enters "n" to exit. With this little snippet of code, you store each array of Integer objects in a master ArrayList. Then you can do whatever you need to with the data. You can access the first element of each Integer object array to get the length. As you were confused how to isolate this value, the above snippet does that for you.
I would also advise you to add your parse statement in a try-catch block to provide error handling for invalid input that cannot be parsed to an integer.
This is one way of doing it with default arrays.
import java.util.Scanner;
public class ScanList {
public static void main(String[] args){
System.out.println("Array:");
Scanner s = new Scanner(System.in);
String line = s.nextLine();
String[] nums = line.split(",");
int[] result = new int[Integer.parseInt(nums[0])];
for(int i = 0; i<result.length;i++){
result[i]=Integer.parseInt(nums[i+1]);
}
for(int r:result){
System.out.println(r);
}
}
}
This is what I came up with:
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Insert the first series of numbers: ");
String number1 = input.nextLine();
System.out.println("Insert the second series of numbers: ");
String number2 = input.nextLine();
String[] items = number1.split(" ");
String[] items2 = number2.split (" ");
List<String> itemList = new ArrayList<String>(Arrays.asList(items));
itemList.remove(0);
Collections.sort(itemList);
System.out.println(itemList);
} // End of main method