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Printing out the array position from a number input by a user

Question:
I need to create an array that holds 1000 integers ranging from 1-100. I then need to ask the user for an input and find out if the number the user has input is present in the array. If its not, then I have to output the message that it is not in the array.
I populated the array with random numbers, just need to find out how to search for the number in the array. I tried using a while loop to condition the for loop, but cant because the random generator and searcher would be in the same loop. Is there a way to linearly search for the number?
import java.util.Scanner;
public class Main
{
public static void main(String[] args)
{
Scanner reader = new Scanner(System.in);
int[] numbers = new int[1000];
System.out.println("Please enter a number: ");
int n = Integer.parseInt(reader.nextLine());
for(int i = 0; i < 1000; i = i + 1)
{
numbers[i] = (int)(Math.random()*100);
}
}
}

Try this
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
int[] numbers = new int[1000];
boolean found = false;
System.out.println("Please enter a number: ");
int n = Integer.parseInt(reader.nextLine());
for(int i = 0; i < 1000; i = i + 1)
{
numbers[i] = (int)(Math.random()*100);
}
for(int i =0; i < 1000; i++){
if(numbers[i] == n){
found = true;
System.out.println(numbers[i] + " Appears first at index " + i);
break;
}
}
if(!found){System.out.println("Number " + n + " is not in the list");}
}

How to write Java statement to display integers between 2 numbers?

I am new to java coding. I have written the code below to the problem: How can I write a statement that can be used in a Java program to read two integers and display the number of integers that lie between them, including the integers themselves?
I couldn't run it in Eclipse. When I try to run it through Eclipse, it tells me "The selection cannot be launched, and there are no recent launches. Anyway, can someone please tell me if this code correct? Are there any errors in it?
import java.util.Scanner;
public class Assignment4 {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
System.out.print("Enter the first integer:10");
int first = s.nextInt();
System.out.print("Enter the second integer:20");
int second = s.nextInt();
System.out.println("How many integers are between "+first+" and "+second+"???");
}
}

Please put some more effort on your query, for sure you can come up with your answers by yourself and you will learn faster. For now You can refer to below answer.
package com.barnwal.jeetendra.learn;
import java.util.Scanner;
public class Assignment4 {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
System.out.print("Enter the first integer:");
int first = s.nextInt();
System.out.print("Enter the second integer:");
int second = s.nextInt();
System.out.println("How many integers are between " + first + " and "
+ second + "???");
// To print number of integer between entered number
if (second > first) {
System.out.println("Answer : " + (second - first - 1));
// To print the numbers
for (int i = first + 1; i < second; i++)
System.out.print(i + " ");
} else {
// To print number of integer between entered number
System.out.println("Answer : " + (first - second - 1));
// To print the numbers
for (int i = second + 1; i < first; i++)
System.out.print(i + " ");
}
}
}

To avoid the unnecessary if-else statement to look which value is bigger, you can also use the functionality of the class java.lang.Math like this
Scanner s = new Scanner(System.in);
System.out.print("Enter the first integer:");
int first = s.nextInt();
System.out.print("Enter the second integer:");
int second = s.nextInt();
int small = Math.min(first, second) ;
int big = Math.max(first, second);
System.out.println("How many integers are between " + small + " and " + big + "???");
System.out.println("Answer : " + (big - small + 1));
// To print the numbers
for (int i = small; i <= big; i++)
System.out.print(i + " ");

You can use looping like this:
if (first > second){
big = first;
small = second;
}
else if (second > first){
big = second;
small = first;
}
for (int i = small; i <= big; i++)
System.out.print(i + " ");

first of all, when you use resources (System.in) you should close them. You can do it with try-finally or you can use try-with-resources.
Here is your code:
import java.util.Scanner;
public class Assignment4 {
public static void main(String[] args) {
try (Scanner s = new Scanner(System.in)){
System.out.print("Enter the first integer:10");
int first = s.nextInt();
System.out.print("Enter the second integer:20");
int second = s.nextInt();
System.out.println("How many integers are between "+first+" and "+second+"???");
if (first != second)
System.out.println("Answer: " + Math.abs(first-second - 1));
else
System.out.println("Answer: 0");
}
}
}

How about this:
int diff = second - first - 1;
let secont = 25 and first = 23 so the output will be:
25-23-1 = 1;
which is 24

Java User Input array is only capturing 3 integers instead of five

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 am trying to write a program that allows me to input multiple integers, but it won't allow me to enter in my set of integers

My code won't allow me to enter in multiple integers to where it can then compute the sum, the count of integers, the minimum, and the sum of positive even integers. I am not sure if I need another method or if im calling for the wrong things.
import java.util.Scanner;
public class Assignment2 {
private static final Scanner input = null;
private static int n;
public static void main(String[] args){
Scanner scan = new Scanner(System.in);
int sum=0, minNumber=0, nCount=0, countEvenIntegers=0;
Scanner sc = new Scanner(System.in);
int i = sc.nextInt();
//when code reads 0, code terminates
int[] numbers = new int[4];
for(int i=0; i<4; i++){
numbers[i] =sc.nextInt();
}
while(!(n==0)){
sum += n;
n = input.nextInt();
}
class SumOfValues {
public int sum(int...vals){
int sum=0;
for (int val : vals) {
sum+= val;
}
return sum;
}
}
class CountingInts{
public void main(String[] args){
Scanner input=new Scanner(System.in);
int count=0;
System.out.print("Numbers: ");
while (input.hasNextInt()){
input.nextInt();
count++;
}
System.out.print(count);
input.close();
}
}
int sumPositive = 0;
System.out.println("The minimum integer is " + minNumber + "\nThe count of integers is "
+ nCount + "\nThe sum of positive integers is " + sumPositive + "\nThe count of even integers in the sequence is " +
countEvenIntegers );
}
}

It looks like you are an absolute beginner, so I'd recommend not dealing with functions and classes and all that, and just write everything linearly. I'm not sure why you have all those functions, classes and variables, but to help you, this is probably the simplest way to achieve what you are trying to do.
import java.util.Scanner;
public class Assignment2 {
public static void main(String[] args) {
int sum = 0, minNumber = 0, nCount = 0, countEvenIntegers = 0;
Scanner sc = new Scanner(System.in);
while (true) {
int input = sc.nextInt();
if (input == 0) {
break;
}
sum += input;
nCount += 1;
}
System.out.println("The minimum integer is " + minNumber);
System.out.println("The count of integers is " + nCount);
System.out.println("The sum of positive integers is " + sum);
System.out.println("The count of even integers in the sequence is " + countEvenIntegers);
}
}
Note that I've not added the minimum interger and count of even intergers for you to complete.

Not quite sure what you are doing in your code since you are not doing any operations on the variables you are outputting, and thus should not expect the output to be any other than 0.
Also, your inner classes are really weird.
Here is an example (based on your code) that does what you want. Plenty of ways of achieving your goal, but I think this is simple enough:
import java.util.Scanner;
import java.util.*;
public class Assignment2{
private static final Scanner input = null;
private static int n;
public static void main(String[] args){
Scanner scan = new Scanner(System.in);
int sum=0, minNumber=0, nCount=0, countEvenIntegers=0, sumPositive = 0;
Scanner sc = new Scanner(System.in);
List<Integer> numbers = new ArrayList<Integer>();
while(true) {
int i = sc.nextInt();
if(i == 0) {
break;
}
numbers.add(i);
}
if(numbers.size() > 0) {
minNumber = numbers.get(0);
}
for (int number : numbers) {
sum += number;
if(minNumber > number) {
minNumber = number;
}
if(number % 2 == 0) {
countEvenIntegers++;
}
if(number > 0 ) {
sumPositive += number;
}
}
nCount = numbers.size();
System.out.println("The minimum integer is " + minNumber + "\nThe count of integers is "
+ nCount + "\nThe sum of positive integers is " + sumPositive + "\nThe count of even integers in the sequence is " +
countEvenIntegers + "\nThe total sum is " + sum);
}
}

While loop not working

Hi I am fairly new to java and trying to familiarize myself to it by doing some exercises online.
How do i properly code the while loop so that everytime the user input is wrong it asks the same question again and does not proceed to the next line of code
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Array {
public static void main(String[] args) {
Scanner dataIn = new Scanner(System.in);
int entries = 0;
List<Integer> grade = new ArrayList<Integer>();
System.out.println("Enter number of students? ");
entries = dataIn.nextInt();
boolean checker = true;
while (checker){
for (int i = 0; i < entries; i++){
int input;
int addToList;
System.out.println("Enter grade for student: ");
input = dataIn.nextInt();
grade.add(input);
if (input >= 0 && input<= 100) {
}else {
System.out.println("invalid input try again..");
checker = false;
}
}
}
int sum = 0;
int count = grade.size();
double mean;
for (int grades : grade){
sum+= grades;
}
mean =(double)sum/count;
System.out.println("The Grades are: " + grade);
System.out.println("The number of elements in the Array is " + grade.size());
System.out.println("The average is: " + mean);
}
}

Your logic is backwards. You want the loop to continue if the input is incorrect. There are two ways to fix this:
Change while(checker) to while(!checker)
Change checker=false to checker=true after printing the error message. And set checker=false in the if branch.
It might help if you change the name of your checker variable to something that reads more directly. For example isInputCorrect reads very nicely when you write while(!isInputCorrect) and it also makes it more clear what the values of true and false represent.

try this :
boolean checker = true
for(int i=0;i< entries;i++){
int input;
System.out.println("Enter grade for student: ");
input = dataIn.nextInt();
while(checker){
if(input >= 0 && input<= 100){
grade.add(input);
checker = false;
}else{
System.out.println("invalid input try again..");
}
}
checker = true;
}

You could try this
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Array {
public static void main(String[] args) {
Scanner dataIn = new Scanner(System.in);
int entries = 0;
List<Integer> grade = new ArrayList<Integer>();
System.out.println("Enter number of students? ");
entries = dataIn.nextInt();
for (int i = 0; i < entries; i++) {
int input;
do{
input = dataIn.nextInt();
if (input >= 0 && input <= 100) {
grade.add(input);
}else{
System.out.println("invalid input try again..");
}
}while(!(input >= 0 && input <=100));
}
dataIn.close();
int sum = 0;
int count = grade.size();
double mean;
for (int grades : grade) {
sum += grades;
}
mean = (double) sum / count;
System.out.println("The Grades are: " + grade);
System.out.println("The number of elements in the Array is " + grade.size());
System.out.println("The average is: " + mean);
}
}

instead of doing while(checker)
make a loop for while(running)
then send it to the keyboard.nextInt()
if its the wrongAnswer than it will loop, if its correct than set running to false
and have code that follows the while loop