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invalid value user input ask again to place into array

Scanner scanner = new Scanner(System.in);
int grade[] = new int[3];
for (int i = 0; i < grade.length; i++) {
System.out.println("Enter your test score:");
grade[i] = scanner.nextInt();
}
I've been trying to figure out how to make it so if the user input is below 0 or above 100 it will ask again. I'm very new to Java and this is the first language I'm learning. I would appreciate any pointers. Do I need to use a do-while loop instead of a for loop for this? Or do I implement an if statement into the for loop?

You can validate the input by putting an if block inside the for loop.
However, since your loop will only execute three times, you should change your increment condition only when user enters correct input or else not.
You also can use while loop here.
Here is some example code:
for (int i = 0; i < grade.length; i++)
{
System.out.println("Enter your test score:");
if(grade[i] < 0 || grade > 100)
{
i--;
continue;
}
grade[i] = scanner.nextInt();
}
The if block will check that if the input is outside boundaries, decrement i and restart the loop.

What I suggest is, instead of incrementing i in loop, you can increase the value in if condition. Like below,
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int grade[] = new int[3];
for (int i = 0; i < grade.length;) {
System.out.println("Enter your test score:");
int temp = scanner.nextInt();
if (temp >= 0 && temp <= 100) {
grade[i] = temp;
i++;
}else {
System.out.println("Please enter valid score");
}
}
scanner.close();
}
This basically gets a input value from user, if the value is greater or equal to 0 && lesser or equal to 100,then adds it to the Array and increments the loop count(array index value we can call it), else, prints message asking for valid input.

Instead of shoving the validation logic somewhere within the loop, you could also write a small utility method which neatly asks for valid input, and continues to do so until the user finally inputs something valid:
int promptInt(Scanner scanner, int min, int max, String errorMessage) {
while (true) {
int input = scanner.nextInt();
if (min <= input && input <= max) {
return input;
}
else {
System.out.println(errorMessage);
}
}
}
You could then simplify the loop:
int grade[] = new int[3];
for (int i = 0; i < grade.length; i++) {
System.out.println("Enter your test score:");
grade[i] = promptInt(0, 100, "Please enter a valid number");
}

How to make the program to check the instance of a letter in java?

I am creating a cash register where I have to use a scanner and can only have 5 input amounts. It has to also include hst and that is by only having a "h" after or before an amount. My question is how would the program recognize that I have put an "h" after or before an amount? This seems to be done only using a string variable, so how would I accomplish that? I have to store the inputs in an array, and so I got that to work.
My Code:
// Import scanner class
import java.util.Scanner;
// Create class and method
class Main {
public static void main(String[] args) {
// Declare the scanner object and create scanner variables
Scanner inp = new Scanner(System.in);
System.out.println("Press any key to start");
String key = inp.nextLine();
System.out.println("\nEnter the amount of each item");
System.out.println("Upto 5 inputs are allowed!\n");
// Define an array double variable, set the limit to 5 inputs
double[] numbers = new double[5];
// Create a for loop to input any numbers 5 times
for (int i = 0; i < numbers.length; i++){
// Add a scanner input to let the user type out the values
numbers[i] = inp.nextDouble();
}
}
}

below code asks the user input for 5 times , and only valid values will be in the Array , Vald values are the values with 'h' at start or end and should only occur once. i.e. at 'h' at both end and start or more than once is invalid.
public static void main(String[] args) throws ParseException {
int counter = 1;
Double[] result = new Double[5];
int index = 0;
while(counter <= 5) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter an Amount ");
String value = scanner.nextLine();
int indexOfH = value.indexOf("h");
int lastIndexOfH = value.lastIndexOf("h");
boolean containsHatstartsOrEnd = indexOfH == 0 || indexOfH == (value.length()-1);
if(containsHatstartsOrEnd && indexOfH==lastIndexOfH){ //Validate h at begins or end and should contains only once
result[index] = Double.parseDouble(value.replace("h", ""));
index++;
}
counter++;
}
System.out.println("Printing Valid values");
for(int i=0; i< result.length; i++) {
if(result[i]!=null) {
System.out.println(result[i]);
}
}
}
input & result
Enter an Amount 13.45h
Enter an Amount 55h.65
Enter an Amount 32h.33h
Enter an Amount h100.23
Enter an Amount h20
Printing Valid values
13.45
100.23
20.0

Flag variable with user input to quit

I have a program that is supposed to simulate a game of poker in java. I have a method class called Poker and a check class called CheckPoker which calls the methods in the method class. I haven't even been able to check if the algorithmic part works because while asking if the user would like to switch out any cards. The loop should quit after 5 cards have been entered or if the user enters "1" but in running the program, the for loop doesn't quit until 5 card values have been entered and then throws a "java.lang.ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 56" error. I have tried a for loop, a while loop, a do-while loop, but none have seemed to work thus far.
import java.util.*;
public class Poker {
private String[] deck = {
"D1","D2","D3","D4","D5","D6","D7","D8","D9","D10","DJ","DQ","DK","DA",
"C1","C2","C3","C4","C5","C6","C7","C8","C9","C10","CJ", "CQ","CK","CA",
"H1","H2","H3","H4","H5","H6","H7","H8","H9","H10","HJ", "HQ","HK","HA",
"S1","S2","S3","S4","S5","S6","S7","S8","S9","S10","SJ", "SQ","SK","SA"};
private List<String> hand = new ArrayList<>();
public Poker(){
Collections.shuffle(Arrays.asList(deck));
}
public void playGame(){
System.out.print("The first five cards are: ");
for(int i = 0; i<5; i++){
System.out.print(deck[i] +", ");
}
System.out.println(" ");
int k = 0;
String j;
List<String> discard = new ArrayList<>();
Scanner in = new Scanner(System.in);
System.out.println("Enter up to 5 cards you want to get rid of (1 to quit): ");
while (k<5) { //this is the loop I'm having trouble with
j = in.next();
if(!j.equals("1")){
j = in.next();
discard.add(j);
k++;
}else{
break;
}
}
List deckList = Arrays.asList(deck);
String[] discard1 = discard.toArray(new String[0]);
for(int l = 0; l<k; l++){
int m = deckList.indexOf(discard1[l]);
String n = deck[m];
deck[m] = deck[l+5];
deck[l+5] = n;
}
System.out.print("Your new hand is: ");
for(int i = 0; i<5; i++){
System.out.print(deck[i] +", ");
hand.add(deck[i]);
}
System.out.println(" ");
}

Try the code below. It seems you were grabbing two cards per iteration and not capturing them all in the ArrayList.
Scanner in = new Scanner(System.in);
System.out.println("Enter up to 5 cards you want to get rid of (1 to quit): ");
while (k<5) { //this is the loop I'm having trouble with
j = in.nextLine();
if(j.equals("1") {
break;
}
discard.add(j);
k++;
}

For loop: populate array from user input [duplicate]

This question already has answers here:
Scanner is skipping nextLine() after using next() or nextFoo()?
(24 answers)
Closed 4 years ago.
I was setting up a small app that asks a user to determine the array size and then populate it. The used "for" loop skips the index 0; but I'm uncertain why.
If you run this code with 1 as the array size it skips over the user inputting the first word.
The issue is certainly on the for-loop but it is so simple that I don't see it.
Thanks!
import java.util.Scanner;
public class WordRandomizerAdvanced {
public static void main(String[] args) {
int arrayDimesion;
Scanner sc = new Scanner(System.in);
System.out.println("****************************************************");
System.out.println("******** Welcome to Word Randomizer ADVANCED********");
System.out.println("****************************************************");
//Get array size
System.out.println("How many words would you like to enter?");
arrayDimesion = sc.nextInt();
String[] wordArray = new String[arrayDimesion];
//Populate with user input
for (int i=0; i<arrayDimesion; i++) {
System.out.println("Please enter a word");
wordArray[i] = sc.nextLine();
}
//Print all entered Strings
System.out.println("This are the words you entered: ");
for(int i = 0; i < wordArray.length; i++) {
System.out.println(wordArray[i]);
}
//Print random string from array
int r = (int)(Math.random() * wordArray.length);
System.out.println("The random word is: " + wordArray[r]);
}
}

Change your
arrayDimesion = sc.nextInt();
to
arrayDimesion = Integer.parseInt(sc.nextLine());
Reason: sc.nextInt() doesn't consume the newline character that you give after taking arrayDimesion input. This later on gets consumed in the next sc.nextLine() call.
PS: It might throw NumberFormatException. So you can handle it like :
try {
arrayDimesion = Integer.parseInt(sc.nextLine());
} catch (NumberFormatException e) {
e.printStackTrace();
}

The below code is clean, easy to read and handles the edge cases.
import java.util.Scanner;
public class WordRandomizerAdvanced {
public static void main(String[] args) {
int numOfWords;
Scanner scanner = new Scanner(System.in);
System.out.println("****************************************************");
System.out.println("******** Welcome to Word Randomizer ADVANCED********");
System.out.println("****************************************************");
//Get array size
System.out.println("How many words would you like to enter?");
numOfWords = Integer.parseInt(scanner.nextLine());
String[] wordArray = new String[numOfWords];
//Populate with user input
System.out.println("Please enter the word(s)");
for (int i = 0; i < numOfWords; i++) {
wordArray[i] = scanner.nextLine();
}
//Print all entered Strings
System.out.println("These are the words you entered: ");
for (int i = 0; i < numOfWords; i++) {
System.out.println(wordArray[i]);
}
//Print random string from array
if (numOfWords == 0) {
System.out.println("You didn't enter a word");
} else {
int r = (int) (Math.random() * numOfWords);
System.out.println("The random word is: " + wordArray[r]);
}
}
}

Validate multiple inputs to an array in java

I have a HOMEWORK assignment that involves users inputs.
I want to ask the user for three integer inputs in the range 1-7 and store them in an array.
What I have so far seems to validate properly if all inputs are over 7 and rules out strings etc inputs and but still allows for a single input to be over 7.
Any help is appreciated.
Scanner in = new Scanner(System.in);
boolean valid = false;
int[] inputRange = new int[3];
while(!valid)
{
System.out.println("enter three numbers: ");
if(in.hasNextInt())
{
for(int i = 0; i< inputRange.length; i++)
{
inputRange[i] = in.nextInt();
if(inputRange[i] >= 1 && inputRange[i] <= 9){
valid = true;
}
}
}else{
in.next();
}
}

Your logic is fine, but you need to restart valid to false again each time user is going to enter a new digit.
Here's how you can validate user input to be between 1-9 with a do-while using your same logic just a little bit different.
Also next time be sure to post a valid MCVE and not just "snippets" (it should include a main method and imports)
import java.util.Scanner;
public class ValidationOfNumbers {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
boolean valid = false;
int[] inputRange = new int[3];
int counter = 0;
int number = 0;
System.out.println("Enter 3 digits between 1-9"); //Ask for digits, numbers can have multiple digits, while digits are numbers from 0-9
for (int i = 0; i < inputRange.length; i++) {
valid = false; //Restart "valid" variable for each new user input
do {
number = in.nextInt();
if (number >= 1 && number <= 9) {
valid = true; //If valid, it will exit do-while
} else {
System.out.println("Enter a valid digit between 1-9");
}
} while (!valid);
inputRange[i] = number; //We know it's valid because it went out of do-while, so we can now store it in the array
}
for (int i = 0; i < inputRange.length; i++) {
System.out.println(inputRange[i]);
}
}
}

Here is the code
Scanner in = new Scanner(System.in);
int count = 0;
int data[] = new int[3];
while(count < 3) {
if(in.hasNextInt()) {
int val = in.nextInt();
if(val>=1 && val <=7) {
data[count] = val;
count++;
}
}
else {
in.next();
}
}