Basically I have to prompt a user to enter 10 string values, and then in another loop print them in ascending order, then in a final loop, print them in descending order. My array is bringing back null, obviously because I am not prompting users to enter actual information into the array object. I am really stuck on this. I know I need to somehow reference the "userStrings[]" array in my first while loop. I keep researching and keep getting integer loops questions and For loops. This has to be a while loop. I just can no figure out how to get the userStrings[] to actually fill up when the user enters the values. How do I get it linked in the loop?
public class HomeWork10
{
public static void main(String[] args)
{
String[] userStrings = new String[10];
int count = 0;
int count2 = 0;
while (count < 10)
{
System.out.println("Please enter a string value ");
Scanner input = new Scanner(System.in);
String userInput = input.next();
count++;
}
while (count2 < 1)
{
System.out.println(Arrays.asList(userStrings));
count2++;
}
}
}
You are not putting the values in the String[]
Do it like this:
while (count < 10) {
System.out.println("Please enter a string value ");
Scanner input = new Scanner(System.in);
String userInput = input.next();
userStrings[count] = userInput;
count++;
}
Also, declare Scanner input = new Scanner(System.in) outside your while() {...}
See below code snippet may solve your problem.
package com.suresh;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;
public class HomeWork10 {
public static void main(String[] args) {
String[] userStrings = new String[10];
int count = 0;
System.out.println("\t Reading Array Elements ");
while (count < 10) {
System.out.print("\t Please enter a string value : ");
Scanner input = new Scanner(System.in);
userStrings[count] = input.next();
count++;
}
System.out.println("\t PRINTING ORIGINAL ARRAY OF ELEMENTS ");
count = 0;
while (count < userStrings.length) {
System.out.println("\t " + userStrings[count]);
count++;
}
Collections.sort(Arrays.asList(userStrings), new StringAscComparator());
System.out.println("\t ASCENDING ORDER ");
count = 0;
while (count < userStrings.length) {
System.out.println("\t " + userStrings[count]);
count++;
}
System.out.println("\t DESCENDING ORDER ");
Collections.sort(Arrays.asList(userStrings), new StringDescComparator());
count = 0;
while (count < userStrings.length) {
System.out.println("\t " + userStrings[count]);
count++;
}
}
static class StringAscComparator implements Comparator<String> {
#Override
public int compare(String o1, String o2) {
return o1.compareTo(o2);
}
}
static class StringDescComparator implements Comparator<String> {
#Override
public int compare(String o1, String o2) {
return o2.compareTo(o1);
}
}
}
You created the array with 'String[] userStrings = new String[10];' and inside your while loop to access it you need to do something like this 'userStrings[0] = input.next()' This says the first item in the array userStrings will be set to input.next(). I'm not great at java so I'm not sure what input.next() will do though.
Related
I'm quite new to Java and I've been asked to create a program in which the user is able to input two values and store them in separate arrays. The two values I'm asking the user are name and cell number, then I must allow the user to search by typing either a name or a cell number and return the corresponding name or cell number. I made it possible to input the values and search within them by number but when I try searching by name I get this error :
Exception in thread "main" java.lang.NumberFormatException: For input string: "B"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.base/java.lang.Integer.parseInt(Integer.java:652)
at java.base/java.lang.Integer.parseInt(Integer.java:770)
This is my code:
import java.util.Scanner;
public class HW {
static Scanner sc = new Scanner(System.in);
private static int i, x = 2;
static String names[] = new String[x];
static int numbers[] = new int[x];
public static void main(String[] args) {
Input();
Compare();
}
public static void Input() {
System.out.println("Enter a name followed by the persons number");
while (i < x) {
System.out.println("NAME: ");
names[i] = sc.next();
System.out.println("NUMBER: ");
numbers[i] = sc.nextInt();
i++;
}
}
public static void Compare() {
System.out.println("=======SEARCH=======\nSEARCH CRITERIA: ");
var temp = sc.next();
System.out.println("NAME\tNUMBER");
for (i = 0; i < numbers.length; i++)
if ((names[i].equals(temp)) || (numbers[i] == Integer.parseInt(temp.trim()))) {
System.out.println(names[i] + "\t" + numbers[i]);
}
}
}
Thanks! :)
Looking at your problem statement it doesn't seem like you need to do any additional processing on numbers. Hence, even if you store the number as a string it should be fine in this case.
Hence after getting a user search criteria, you could do a simple string search within both arrays.
Hope this helps :)
First of all, the highest number that can be represented as an int in Java is 2147483647 (214-748-3647). This clearly will not be able to hold a high enough number to accommodate any phone number. To address this issue and also fix your main error, I would suggest storing the numbers as a string instead. Here's my solution:
import java.util.Scanner;
public class HW {
static Scanner sc = new Scanner(System.in);
private static int x = 2;
static String names[] = new String[x];
static String numbers[] = new String[x];
public static void main(String[] args) {
input();
compare();
}
public static void input() {
System.out.println("Enter a name followed by the persons number");
for (int i = 0; i < x; i++) {
System.out.println("NAME: ");
names[i] = sc.next();
System.out.println("NUMBER: ");
numbers[i] = sc.next();
i++;
}
}
public static void compare() {
System.out.println("=======SEARCH=======\nSEARCH CRITERIA: ");
String temp = sc.next();
System.out.println("NAME\tNUMBER");
for (int i = 0; i < numbers.length; i++) {
if ((names[i].equals(temp)) || numbers[i].equals(temp)) {
System.out.println(names[i] + "\t" + numbers[i]);
}
}
System.out.println("===END OF SEARCH====")
}
}
Please also note that I un-defined your variable i. As far as I can see there's no reason for you to be defining it. Hope this helps, good luck!
This code is supposed to capture 5 user integers, print them out, then print them in reverse. It is capturing the first int only, and printing it 3 times, then printing the first integer again 5 more times without reversing. Test ends with "Process finished with exit code 0" which I think is says the program finished without errors -- which of course is not correct. I assume the issue is in how the user input array is stored. I have it assigning as userNum[i] with a limited array of 5, and int i =0 to begin array storage at userNum[0], so I'm not clear on why all the inputs are not captured up to userNum[4].
Thank you for any insight you can provide. I am very new to java and this is prework for my java class.
import java.util.Scanner;
public class ArrayReverse {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in); // scanner for input
final int NUM_VALS = 5; // number on int user able to enter
int[] userNum = new int[NUM_VALS]; // user integers storage
int j = 0;
int i = 0;
System.out.println("Enter integer values: ");
userNum[i] = scnr.nextInt(); // capture user input int
for (j = 0; j < NUM_VALS; j++) {
System.out.print("You entered: ");
System.out.println(userNum[i]);
++j;
}
System.out.print("\nNumbers in reverse: "); // statement to Print reversed array
for (j = NUM_VALS - 1; j >= 0; j--) {
System.out.print(userNum[i] + " ");
}
}
}
You need to work more about on for loops and study how to iterate values in for loop, the problem in your i,j variables.
Here I fix your code.
import java.util.Scanner;
public class ArrayReverse {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in); // scanner for input
final int NUM_VALS = 5; // number on int user able to enter
int[] userNum = new int[NUM_VALS]; // user integers storage
int j = 0;
int i = 0;
//for 5 inputs you need loop
for(;i<NUM_VALS;i++){
System.out.println("Enter integer values: ");
userNum[i] = scnr.nextInt(); // capture user input int
}
for (j = 0; j < NUM_VALS; j++) {
System.out.print("You entered: ");
System.out.println(userNum[j]);
//++j; //no need to increment as you already did in for loop
}
System.out.print("\nNumbers in reverse: "); // statement to Print reversed array
for (j = NUM_VALS - 1; j >= 0; j--) {
System.out.print(userNum[j] + " ");// userNum[0] = your last value which you reverse
}
}
}
Here is a solution using the collections framework:
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
public class ArrayReverse {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in); // scanner for input
final List<Integer> numbers = new ArrayList<>();
System.out.println("Enter any number of integers. (whitespace delimited. enter a non-integer to quit.): ");
while (scnr.hasNextBigInteger()) {
final int n = scnr.nextInt();
System.out.println("Parsed: " + n);
numbers.add(n);
}
System.out.println("Done reading user input.");
System.out.println("Your input: " + numbers);
Collections.reverse(numbers);
System.out.println("Your input reversed: " + numbers);
}
}
I have provided you with a solution. This is a clean way of doing it.
nextInt() reads the next integer that the user inputs. Notice that this will throw a InputMismatchExceptionif the user does not input a integer as value.
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
List<Integer> input = new ArrayList<Integer>();
//Simple loop that will read 5 user inputs
//and add them to the input list
for(int i = 0; i < 5; i++){
input.add(scanner.nextInt());
}
//print the 5 values
for(Integer val : input){
System.out.println(val);
}
//reverse the 5 values
Collections.reverse(input);
//print the 5 values again, but they are now reversed
for(Integer val : input){
System.out.println(val);
}
}
I've been working on this program and am currently stuck. The HW prompt is to prompt a user to input numbers, save it as an array, find the number of odd numbers & the percentages then display those values back to the user.
Currently I am trying to write to part of the code that finds the percentage of the odd numbers in the array but the return isn't displaying and i just cant figure it out. Any ideas? Thank you!
import java.util.*; // import java course for Scanner class
public class Integers {
public static void main(String[] args) {
Scanner console = new Scanner(System.in);
System.out.println("Please input a series of numbers");
int inputs = Integer.parseInt(console.next());
int[] arraysize = new int[inputs];
Oddvalues(arraysize);
}
public static int Oddvalues (int[] size) {
int countOdd = 0;
for (int i = 1; i < size.length; i++) {
if(size[i] % 2 != 0) {
i++;
}
}
return countOdd;
}
}
Consider the following code, which appears to be working in IntelliJ locally. My approach is to read in a single line from the scanner as a string, and then to split that input by whitespace into component numbers. This avoids the issue you were facing of trying to directly create an array of integers from the console.
Then, just iterate over each numerical string, using Integer.parseInt(), checking to see if it be odd.
public static void main(String[] args) {
Scanner console = new Scanner(System.in);
System.out.println("Please input a series of numbers");
String nextLine = console.nextLine();
String[] nums = nextLine.split(" ");
int oddCount = 0;
for (String num : nums) {
if (Integer.parseInt(num) % 2 == 1) {
++oddCount;
}
}
double oddPercent = 100.0*oddCount / nums.length;
System.out.println("Total count of numbers: " + nums.length + ", percentage odd: " + oddPercent);
}
In the function Oddvalues you promote i instead of promoting countOdd. And the loop should start from 0 not 1.
Try this
import java.util.*;
import java.lang.*;
import java.io.*;
public class OddVals{
public static void main(String[] args) throws java.lang.Exception {
Scanner sc = new Scanner(System.in);
int[] array = new int[sc.nextInt()]; // Get the value of each element in the array
System.out.println("Please input a series of numbers");
for(int i = 0; i < array.length; i++)
array[i] = sc.nextInt();
System.out.println("Number of Odds:" +Oddvalues(array));
printOdd(array);
}
public static int Oddvalues (int[] size) {
int countOdd = 0;
for (int i=0; i < size.length; i++){
if(size[i]%2 != 0)
++countOdd;
}
return countOdd;
}
public static void printOdd(int[] arr)
{
for(int i=0;i<arr.length;++i)
{
if(arr[i]%2==1)
System.out.print(arr[i]+" ");
}
}
import java.util.*; // import java course for Scanner class
public class Integers {
public static void main(String[] args) {
List<Integer> intList = new ArrayList<Integer>();
Scanner console = new Scanner(System.in);
System.out.println("Please input a series of numbers");
while (console.hasNext())
{
String str = console.next();
try
{
if(str.equals("quit")){
break;
}
int inputs = Integer.parseInt(str);
System.out.println("the integer values are" +inputs);
intList.add(inputs);
}
catch (java.util.InputMismatchException|NumberFormatException e)
{
console.nextLine();
}
}
console.close();
double d = Oddvalues(intList);
System.out.println("the percent is" +d);
}
public static double Oddvalues (List<Integer> list) {
int count = 0;
for( Integer i : list)
{
if(!(i%2==0))
{
count++;
}
}
double percentage = (Double.valueOf(String.valueOf(count))/ Double.valueOf(String.valueOf(list.size())))*100;
return percentage;
}
}
If this helps
I am in a low level java programming class, and I am having trouble figuring something my professor assigned to us. We originally made a program that added integers that were placed in an arraylist. She then asked us to make it as user friendly as possible, without having a specific amount of integers the user inputs. So I came up with this:
public class CalculatorREDONE
{
public static void main(String[] args)
{
ArrayList<Integer> numbers = new ArrayList<Integer>();
System.out.println("Enter any numbers you would like to add. ");
Scanner input = new Scanner(System.in);
do
{
numbers.add((int) input.nextInt()); //inserting input into the arraylist
System.out.println("The sum is " + sum(numbers)); //test output
}while(input.hasNextInt()); // I believe this needs to change but I am unsure what it should be
System.out.println(sum(numbers));
//My Problem here is that the loop doesn't end, therefore cannot print this output
input.close();
}
public static int sum(ArrayList<Integer> list)
{
int total = 0;
for (int i = 0; i < list.size(); i++)
{
total += list.get(i);
}
return total;
}
}
Sorry for the clutter of comments, I'm trying to show any of you my mindset behind what I did. Thank you so much in advance for anyone that has any suggestions!
See if this helps where in you take an input from user to terminate the program.
public class CalculatorREDONE {
public static void main(String[] args) {
List<Integer> numbers = new ArrayList<Integer>();
System.out.println("Enter any numbers you would like to add or -1 to exit");
Scanner input = new Scanner(System.in);
// boolean nextAvailable = true;
while(true)
{
String nextVal = input.nextLine();
if(nextVal.isEmpty()) {
break;
}
numbers.add(Integer.parseInt(nextVal)); //inserting input into the arraylist
// System.out.println("The sum is " + sum(numbers)); //test output
} //while (!input.next().); // I believe this needs to change but I am unsure what it should be
System.out.println(sum(numbers));
//My Problem here is that the loop doesn't end, therefore cannot print this output
input.close();
}
public static int sum(List<Integer> list) {
int total = 0;
for (int i = 0; i < list.size(); i++) {
total += list.get(i);
}
return total;
}
}
Try this -- it takes the input as a string, checks the length. If the user just hits enter the length will not be greater than zero. This catches the number exception from the parseInt by confirming the user has ended their list.
Note that I didn't include your sum portion since it wasn't relevant to the question of breaking the loop. You'll need to re-add
import java.util.Scanner;
import java.util.ArrayList;
public class CalculatorREDONE
{
public static void main(String[] args)
{
ArrayList<Integer> numbers = new ArrayList<Integer>();
System.out.println("Enter any numbers you would like to add. ");
Scanner input = new Scanner(System.in);
String userinput = "xx";
int nextnum = 0;
while (userinput.length() > 0) {
try {
userinput = input.nextLine();
nextnum = Integer.parseInt(userinput);
numbers.add(nextnum);
System.out.println("Taken");
} catch (NumberFormatException e) {
System.out.println("Inputs complete");
}
}
System.out.println(numbers);
input.close();
}
}
package jellyProblem;
import java.util.*;
public class jellyProblem {
public static void main(String[] args){
Scanner input=new Scanner(System.in);
int studentNumbers = input.nextInt();
input.nextLine();
String [] name =new String [100];
int [] volume=new int[100];
while(true){
if (studentNumbers==0)
break ;
else
for(int i=0;i<studentNumbers;i++){
name[i]=input.next();
int length =input.nextInt();
int width =input.nextInt();
int height =input.nextInt();
System.out.printf("\n%s %d %d %d\n",name[i],length,width,height);
volume[i]=length*height*width;
}
int minimum=0,maximum=0;
for(int i=1;i<studentNumbers;++i){
if (volume[i]<volume[minimum])
minimum=i;
if (volume[i]>volume[maximum])
maximum=i;
}
if(volume[minimum]==volume[maximum])
System.out.println("\nno child lost his jelly\n");
else
System.out.printf("\n%s has lost jelly to %s.\n",name[minimum],name[maximum]);
studentNumbers = input.nextInt();
input.nextLine();
}
}
}
First request I don't know how to:
Prevent string duplicates in names[] array like
I want to stop array if characters of name[] is more than past (names[i].length<=10) it doesn't work with me
Maybe you can do it like this:
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class test {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int studentNumbers = input.nextInt();
input.nextLine();
List<String> names = new ArrayList<String>();
int[] volume = new int[100];
// clear all data to make it clean
names.clear();
while (true) {
if (studentNumbers == 0)
break;
else
for (int i = 0; i < studentNumbers; i++) {
String studentName = input.next();
// here is how prevent string duplicates in names[] array like
if (names.contains(studentName)) {
continue;
}
if (studentName.length() > 10) {
break;
}
names.add(studentName);
int length = input.nextInt();
int width = input.nextInt();
int height = input.nextInt();
System.out.printf("\n%s %d %d %d\n", names.get(i), length, width, height);
volume[i] = length * height * width;
}
int minimum = 0, maximum = 0;
for (int i = 1; i < studentNumbers; ++i) {
if (volume[i] < volume[minimum])
minimum = i;
if (volume[i] > volume[maximum])
maximum = i;
}
if (volume[minimum] == volume[maximum])
System.out.println("\nno child lost his jelly\n");
else
System.out.printf("\n%s has lost jelly to %s.\n", names.get(minimum), names.get(maximum));
studentNumbers = input.nextInt();
input.nextLine();
}
}
}
a. Instead of using an Array of string you can use an ArrayList. The ArrayList will give you the power to perform various function over the list of String. Incase you want to write your own method and only allow non duplicates to be inserted into the Array then u can iterate over the array and check whether you encounter the same value. eg.
String newName = input.nextLine();
boolean checkDuplicate = dupliacteFunction(newName,name);
boolean dupliacteFunction(String newName , String []nameArray) {
for(String nameValue : nameArray) {
if(newName .equals(nameValue))
return true;
}
else return false;
}
b. String newName = input.nextLine();
newName.length();// This will give u the size of the string being read.
Please try and implement these changes and then we can suggest further alternatives. Happy Coding!!!
To answer your first question, there is no real way to prevent duplicates in an array. I would use an ArrayList object. If it is absolutely impossible to use an ArrayList, you could create a method like this:
public static String[] removeDupes(String[] array){
ArrayList<String> uniqueItems = new ArrayList<String>();
for(String s : array){
if(uniqueItems.contains(s) == false)
uniqueItems.add(s);
}
array = uniqueItems.toArray(array);
return array;
}
And to answer your second question, I don't know what you mean by "stop array" but it seems like all you need is a simple if-statement with exactly the condition you described.