Any possible way to keep entering numbers, and when the same number is entered 2 or more times an error message arises or something like that? I need this to be answered in Java only. I'm new and I don't know where to go from here. I need help searching values in the array and then printing out all the numbers that have been entered.
public class Test
{
public static void main(String args[])
{
Scanner input = new Scanner(System.in);
System.out.println("How big is the group?: ");
int[] group = new int[input.nextInt()];
for (int i = 0; i < group.length; i++)
{
System.out.println("Please enter number: ");
group[i] = input.nextInt();
}
I think this is what you're looking for. Inside of the for loop, there's a while loop spinning to keep collecting new ints until you enter one that's not already in the list.
for (int i = 0; i < group.length; i++)
{
System.out.println("Please enter number: ");
int next = input.nextInt();
while(Arrays.asList(group).contains(next)) { // Keep asking for new input while the input is already in list
System.out.println("That number is already in the group ... try again.");
next = input.nextInt();
}
group[i] = next;
}
Since this is clearly a "learning exercise", it is only appropriate to give you hints:
You can search an array by stepping through the array indexes and testing the elements at each index.
A method and a class both need a closing } ...
I need this to be answered in Java only.
That is incorrect. What you REALLY need is some hints. If we give you Java code, you miss out on the important learning experience of writing it yourself. And THAT is the WHOLE POINT of the homework. Go ask your teacher if you don't believe me.
Related
I need help checking rows, columns, and boxes for a Sudoku program. I am a high school student that needs help completing this project. If any one could provide help that would be awesome! I am currently working on checking boxes where I have a comment saying "Start Here". Thanks!
import java.util.*;
public class Run
{
Scanner scanner = new Scanner(System.in);
public static void main(String[] args)
{
char [][] board = new char [9][9];
Scanner scanner = new Scanner(System.in);
System.out.println("Welcome to Sudoku!\n");
fill(board);
printBoard(board);
inputLengthandDigits(board);
System.out.println();
printBoard(board);
}
public static void fill(char[][] arr){
for(int row = 0; row < arr.length; row++){
for(int col= 0; col< arr[row].length; col++){
arr[row][col] = '-';
}
}
}
public static void printBoard(char [][] array)
{
for(char[] row: array)
{
for(char play: row)
{
System.out.print(play+ " ");
}
System.out.println();
}
}
public static void inputLengthandDigits(char[][] array){
Scanner in = new Scanner(System.in);
for (int i = 0; i < 9; i++)
{
System.out.println("\nEnter the numbers in row " + (i+1) + ":");
String input = in.nextLine();
String numbers = "123456789-";
boolean numberscheck = false;
boolean endCheck = true;
boolean onlyOnce = true;
//Input Validation Starts Here!
//Checks if Input is only digits 0-9
do{
if(endCheck==false){
System.out.println("\nPlease input numbers only (1-9)!");
input = in.nextLine();
}
if(onlyOnce==false){
System.out.println("\nPlease input numbers only once!");
input = in.nextLine();
}
//Checks Length of User Input
while(input.length() < 9 || input.length() > 9){
System.out.println("\nPlease input 9 numbers!");
input = in.nextLine();
}
//Start Here
for(int a = 0; a<input.length()-1; a++){
for(int b= a + 1; b<input.length(); b++){
if(input.charAt(a)==input.charAt(b)){
onlyOnce = false;
}
}
}
for(int x = 0; x < input.length(); x++){
char thing = input.charAt(x);
numberscheck = false;
for(int y = 0; y < numbers.length(); y++){
char numbersn = numbers.charAt(y);
if(thing == numbersn){
numberscheck = true;
endCheck = true;
break;
}
}
if(numberscheck == false){
endCheck = false;
break;
}
}
}while(endCheck==false || onlyOnce==false);
for(int j=0; j<9; j++){
array[i][j] = input.charAt(j);
}
}
}
}
My initial response is too long for a comment. I'm not sure I have a solution to your problem, largely because you haven't actually pointed out which bit is a problem yet, but these pointers should help improve things anyway:
Please reformat your code. It is actually quite painful to look at. Spaces should be used consistently around variables, key words, brackets and operands. Opening curly braces should be on the same line as the method signature, for() loop or whatever else comes first. You have random blank lines within methods which don't separate logical sections so are just confusing. The compiler won't care about any of this, but if you can make your code look neater people will instinctively presume you care and are more likely to credit you with the ability to write decent code.
You have declared a new scanner variable three times. This is redundant and wasteful clutter. Either have a single, class-wide scanner, or (preferably), only create a scanner in a method which actually uses it and then remember to call scanner.close() once the scanner is no longer required.
inputLengthandDigits is a weird name. Is 'Lengthand' a single word, or should it be 'inputLengtHandDigits' or 'inputLengthAndDigits'? In camel case, capitalise every word except the first to make the whole easier to read. Whatever it should be, I don't understand from the name what this method does. It isn't inputting anything, it's getting inputs from someone else. Perhaps getData or populateGrid might be more explanatory.
9 appears quite a few times, with no explanation. I know where it came from, because I spend far too much time playing Sudoku, but it is a magic number and these are to be avoided at all costs. I met a magic number in the workplace once, wasted half a day trying to do what could have been a ten minute job if colleagues had recorded what the number was and where it came from. Here, just have a private static final int maxNumber = 9; statement.
A good thing: your main() method has almost no fiddly details in it. You have effectively used method calls to tell a story and describe what is happening elsewhere. This is a really, really good thing to do :)
Some of your logic tests can be tidied up a bit, e.g. !onlyOnce is the same as onlyOnce == false, and input.length() < maxNumber || input.length() > maxNumber can be simplified to input.length() != maxNumber. It's exactly the same logic, but faster to type and easier to read :)
It looks like your code under the //Start here comment is checking that you don't have any duplicate numbers. If you do get duplicate numbers, the program is still going to try and run the next bit of code before asking the user for alternative input. Is that something you want to happen, or a waste of time?
I actually burst out laughing when I saw a variable called 'thing'. Please, find a name which actually describes the purpose of this variable.
I have now run the code, and it rightly pointed out an error when I tried to key in duplicate numbers for row 4. However, it's now stuck there and keeps asking me to try again even when I put in a valid set of digits. This needs to be fixed. Look closely at which flags are triggering the request to retry. Run your code in debugging mode (you are using an IDE like IntelliJ or Eclipse, aren't you?) and deliberately enter a bad row to see the behaviour for yourself and where the logic is going wrong.
This whole method to get the row input, validate it, and then populate the array, is very big and confusing. You need to refactor it into a lot of smaller methods. Here is a suggestion to play with:
private static char[][] populateGrid(char[][] array) {
Scanner scanner = new Scanner(System.in);
for (int i = 0; i <maxNumber; i++) {
String rowData = getRowInput(scanner);
populateRow(array, rowNumber, rowData);
}
scanner.close;
return array;
}
private static String getRowInput(Scanner scanner) {
System.out.println("\nEnter the numbers in row " + (i + 1) + ":");
String input = scanner.nextLine();
while (!isValidInput(input) {
System.out.println("Please enter only the digits 1-9 in any order, with no duplicates or omissions");
input = scanner.nextLine();
}
return input;
}
private static boolean isValidInput(String input) {
if (!rightLengthOfInput(input)) {
return false;
}
if (!allUniqueDigits(input)) {
return false;
}
if (!usesCorrectCharacters(input)) {
return false;
}
return true;
}
I'll leave you to make the different input validation methods. It will largely be a case of moving your existing code, but the method names will help humans understand what each section is doing. This structure also allows you to cleanly add more validation checks, should such a thing be desired in the future.
Things to consider after all that:
Are you going to check that you have a viable Sudoku solution, or will you trust the user to put in correct data such that the columns also have each of the nine digits in them? How will you handle an invalid grid, e.g. each row is identical?
How far does this assignment want you to go? Do you need to systematically remove numbers to get a solvable puzzle rather than a completed grid? Will the assignment stop at a puzzle which can be seen in the console, or do you need a printable format, or will the user be able to play through the program? If the latter option, will this be in the console or using a graphical interface?
I appreciate that there is a lot to think about and work on here. Take it steadily, one step at a time, and keep asking questions if you need too.
I am incredibly new to java and have been given the following task:
Write a Java Program to prompt a user for a 3 letter body part name which has to be in the 'official' list of 3 letter body parts. (Arm, Ear, Eye, Gum, Hip, Jaw, Leg, Lip, Rib, Toe)
If a user makes a guess correctly then display the correct guess as part of a list.
Allow the user to keep guessing until they have all 10.
If a body part is incorrect then display an appropriate message.
Display the number of guesses they have made including
the correct ones.
The advice given was to use Arrays and Collections as well as Exception Handling where appropriate but I don't know where to go from what I've coded so far. Any help would be appreciated so much, thank you.
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String[] bodyparts = new String [10];
bodyparts[0] = "Arm";
bodyparts[1] = "Ear";
bodyparts[2] = "Eye";
bodyparts[3] = "Gum";
bodyparts[4] = "Hip";
bodyparts[5] = "Jaw";
bodyparts[6] = "Leg";
bodyparts[7] = "Lip";
bodyparts[8] = "Rib";
bodyparts[9] = "Toe";
Set<String> bodypartSet = new TreeSet<>();
Collections.addAll(bodypartSet, bodyparts);
System.out.println("Please enter a 3 letter body part: ");
String bodypart = input.nextLine();
if (bodypartSet.contains(bodypart)) {
System.out.println("Correct, " + bodypart + " is on the list!");
} else {
System.out.println("Nope, try again!");
}
}
There are a lot of way to do this. The following, isn't the best or the most efficient, but it should work...
First of all, you have to put your "official" list in a structure, like an array:
private static String[] offList={Arm, Ear, Eye, Gum, Hip, Jaw, Leg, Lip, Rib, Toe};
Now you have to write a method that can find a world in that "offList", like that:
private static boolean find(String word){
for( int i=0; i<offList.length; i++){
if(word.equals(offList[i])) //if "word" is in offList
return true;
}
return false;
}
Now, let's create this guessing game GUI:
public static void main(String[] args){
LinkedList<String> guessed=new LinkedList<>();
String s;
Scanner input = new Scanner(System.in);
while(guessed.size()<offList.length){
System.out.println("Guessed= "+guessed.toString()); //you have to change it, if you want a better look
System.out.print("Try:");
s=input.nextLine();
/*Here we ask to the user the same thing, unless the guessed list
contains all the words of offList.
Every time we print the guessed worlds list*/
if(find(s)){
System.out.println("This world is in offList!");
if(!guessed.contains(s)) //the world is counted only one time!
guessed.add(s);
}else
System.out.println("Sorry...");
}
System.out.println("The complete list is "+guessed.toString());
}
If you want to show this game in a window, you should have to study some Java Swing classes.
EDIT: I post my answer before the main post editing. First of all you have to understand the Collections advantages and usage... When you know all the LinkedList methods, for example, this assignment looks like a joke! ;)
You need a loop for that, otherwise it will only ask for input once.
Something like this should do:
ArrayList<String> bodyParts = new ArrayList<String>();
bodyParts.add("Arm");
bodyParts.add("Ear");
bodyParts.add("Eye");
bodyParts.add("Gum");
bodyParts.add("Hip");
bodyParts.add("Jaw");
bodyParts.add("Leg");
bodyParts.add("Lip");
bodyParts.add("Rib");
bodyParts.add("Toe");
String input = "";
int totalGuesses = 0;
Scanner sc = new Scanner(System.in);
System.out.println("Start guessing...");
while (!bodyParts.isEmpty()) {
totalGuesses++;
input = sc.nextLine();
if (input.length() != 3 || !bodyParts.contains(input)) {
// incorrect, do nothing
System.out.println("Nope.");
} else {
// correct, remove entry
bodyParts.remove(input);
System.out.println("Correct! " + (10 - bodyParts.size()) + " correct guess" + ((10 - bodyParts.size()) != 1 ? "es" : ""));
}
}
System.out.println("Done. You have found them all after " + totalGuesses + " guesses.");
sc.close();
Also, this is case sensitive. It will not find Arm when typing arm. And if you need the number of all guesses you can simply add an int before the loop and increase it inside.
The result of my example:
Start guessing...
arm
Nope.
Arm
Correct! 1 correct guess
Arm
Nope.
Ear
Correct! 2 correct guesses
Eye
Correct! 3 correct guesses
(...)
Rib
Correct! 9 correct guesses
Toe
Correct! 10 correct guesses
Done. You have found them all after 12 guesses.
I'm currently working on an assignment for school and I am almost done but I just have one large problem I need to fix before I can add the final bit.
I need to create a program that prompts you to enter either 1 or 2, Afterwards it asks you to enter three words/names and saves them into an array.
Then, depending on whether you picked 1 or 2, it prints them in alphabetical order or flips around the lowercase and uppercase letters. I didn't add that part yet because I'm trying to fix a problem related to the very first input.
When you input a number other than 1 or 2, I am instructed to display an error message and ask for input again. I am pretty sure what I need to do is get the entire program to go back to the beginning because copy/pasting the entire program again would be bad, lol
A big problem is probably that I'm using if/else statements with for loops inside when I might need to put the entire thing inside a loop? But I'm not sure what condition I would use to start the loop if I put the entire code in it. I must be missing something here.
With what I have now, it gets stuck saying invalid input even if you put in a 1 or 2.
import java.util.Scanner;
public class IsabellaPiantoniLab5 {
public static void main (String[]args) {
//Ask for input
Scanner input = new Scanner(System.in);
System.out.print("Please choose either a number 1 or number 2.");
int numChoice = input.nextInt();
//if choice is 1 or 2
if (numChoice == 1 || numChoice == 2) {
System.out.println("Please enter three names: ");
String nameInput[] = new String[4];
//input loop
for (int i= 0; i < nameInput.length; i++) {
nameInput[i] = input.nextLine();
}
System.out.println("Values are:");
//display values if 1
if (numChoice == 1) {
for (int i=1; i<4; i++) {
System.out.println(nameInput[i]);
}
}
//display values if 2
else if (numChoice == 2) {
for (int i=1; i<4; i++) {
System.out.println(nameInput[i]);
}
}
}
//retry if invalid------i restart from the beginning if this happens
else if (numChoice != 1 || numChoice != 2) {
System.out.println("Invalid value. Please try again.");
//continue;
}
}
}
System.exit(0);
This will terminate the app, thus you can start it again using command line ( START [your app path])
Or
RunTime.getRuntime().exec(“Your app”);
System.exit(0);
Edit I misunderstood the question, I thought you wanted to restart the whole app
After discussing the approach with #csm_dev
It is way either to ask for the user input one more time by emptying the field and showing a message “please enter a valid input” with a clarification message
So, I want to ask the user to input three values (all double) with only one prompt and have them stored in an array (I just started getting familiar with creating objects and arrays). This is what I've got so far:
import java.util.Scanner;
final int ARRAY_LIMIT=3;
Scanner input=new Scanner(System.in);
System.out.println("Enter the points and speed: ");
double entryVal=input.nextDouble();
double[] array=new double[ARRAY_LIMIT];
for(int entriesCounter=0; entriesCounter<array.length; entriesCounter++)
{
array[entriesCounter]=entryVal;
if(array[2]==0)
break;
}
So when I try to run it and I input something like 1.0, 1.0, 10.0, but I get all sorts of code spewed out. The point is to input all 3 values at the same time, eventually use these values in separate equations and terminate if the third number is 0. But I want to first be able to get these values to be stored correctly. I've tried to look at other previously answered questions but couldn't find something that helped me. I'm very new to Java so I'm still bumbling about. Any detailed help would be greatly appreciated.
The best way I think is just read the whole line to String :
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter the points and speed: ");
String entryVal = input.nextLine();
String[] stringArray = entryVal.split(" ");
double[] array = new double[stringArray.length];
for (int i = 0; i < array.length; i++) {
array[i] = Double.valueOf(stringArray[i]);
}
}
Note that each value has to be seperated only by space.
Basically I am trying to write a program that will read a finite set of values from the user then print the average. (I know how to do the calculations so I will leave those out.)
I am having a problem with the logic side of the loop.
I understand that everyone here would prefer that I attempted it but I am new to loops and I am having extreme difficulties understanding loop logic.
I am attempting to do this assignment for my class but the teacher is flying through material and does not help at all when questions are asked. When I ask for help with a problem he says do your best to attempt it and I will grade it accordingly?
I honestly do not know where to start.
import java.util.Scanner;
public class P4Point5 {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String Status = "";
int count = 0;
while (in.hasNext()) {
count++;
}
for (int i = 0; i < count; i++) {
//Do calculations here?
}
}
}
You never get the next element:
while (in.hasNext())
count++;
You are always on the 1st element and asking if there is a 2nd element.
You should use:
while (in.hasNext())
int next = sc.nextInt();
BTW: please avoid statement without curly brackets. It is the root of all evil.
When you read for the first time, you don't read anymore, so hasNext() will stay always true since there will always be next element, which is.. the current element you're reading.
One solution is to do something like that:
String input = null;
while((input = in.next()) != null) {
//...
}
You can try this:
while (in.nextInt() != 'SOME INT TO STOP LOOP')
count++;
Instead of verify every time if we have an entered number, we can verify if the entered number is an stop condition.