I am trying to create a method that will accept the users input for the amount of elements they would like in an array, and the numbers to input for the array.
So far I have the main method which accepts the input from the console using the following code, after that I am not 100% sure if the method I need to create should return an int array or should just print out the results.
import java.util.Scanner;
public class Lab {
public static void main (String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Input amount desired in Array 1");`
int a = input.nextInt();
int [] array1 = new int[a];
for (int i = 0; i < array1.length; i++) {
System.out.println("Input a number");
array1[i] = input.nextInt();}
System.out.println();}
public int swapPairs(int [] array)
Ok, so You just do this:
public void swapPairs(int [] array){
for(int i = 0; i < array.length(); i += 2){
if(i != array.length - 1)
System.out.print(array[i] + " " + array[i+1]);
}
if(array.length % 2 == 1) System.out.print(" " + array[array.length - 1]);
It really depends on what you want to achieve. If you need only to see the results the print is enough but if you return the array you can operate on the one that is changed as you wanted
Related
I'm pretty sure I've done most of the code correctly but I'm returning the wrong thing? I've tried using copyOf() but still had the same issue. It looks like I'm returning the object of an array rather than the elements? I need the method treble to return the original array repeated in order, three times in one array. So [1,2,3,] should look like [1,2,3,1,2,3,1,2,3] when trebled.
Any help would be much appreciated.
import java.util.Scanner;
import java.util.Arrays;
public class ArrayExercises
{
public static void main(String[] args)
{
final int SIZE = 5;
int[] array = new int[SIZE];
Scanner scanner = new Scanner(System.in);
for (int i = 0; i < array.length; i++)
{
System.out.print("Please enter whole number " + (i + 1) + ": ");
int input = scanner.nextInt(); // get input from the user
array[i] = input; // store the value in the array
}
printArray("Input array:", array);
// call method sum and print out the result
int sum = sum(array);
System.out.println("The sum of elements is " + sum);
// call method repeat and print out the result
int[] trebled = repeat(array);
System.out.println("The repeated array is " + trebled);
}
public static void printArray(String msg, int[] array)
{
System.out.println(msg + " " + Arrays.toString(array));
}
public static int sum(int[] array)
{
int s = 0;
for (int i = 0; i < array.length; i++)
s += array[i];
return s;
}
public static int[] repeat(int[] array) //this is the part I'm having trouble with
{
int len = array.length;
int[] multiplied = new int[len*3];
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < len; j++)
{
multiplied[i * len + j] = array[j];
}
}
return multiplied;}
}
Try using:
System.out.println("The repeated array is " + Arrays.toString(trebled));
to print your array instead of printing using the array variable name, because otherwise that will print the address of the array rather than the content.
your method is ok, the issue is how you print it because as mentioned in the comments you do not use your printArray() method in this case.
So try changing this line :
System.out.println("The repeated array is " + trebled);
to :
printArray("The repeated array is " , trebled);
before you help me this is a homework assignment, i have most of all of it done but there is one thing that i cant figure out, 0 doesn't get detected at all. This means if i input 0-9 into the array it will tell me there is only 9 distinct numbers when really there should be 10 and it will print out all the numbers but 0. Can anyone see the problem and please explain it to me becuase i need to understand it.
package javaproject.pkg2;
import java.util.Scanner;
public class JavaProject2 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int[] numArray = new int[10];
int d = 0;
System.out.println("Enter Ten Numbers: ");
for(int i = 0; i < numArray.length; i++){
int num = input.nextInt();
if(inArray(numArray,num,numArray.length)){
numArray[i] = num;
d++;
}
}
System.out.println("The number of distinct numbers is " + d);
System.out.print("The distinct numbers are: ");
for(int i = 0; i < d; i++){
System.out.print(numArray[i] + " ");
}
}
public static boolean inArray(int[] array, int searchval, int numvals){
for (int i =0; i < numvals; i++){
if (searchval == array[i]) return false;
}
return true;
}
}
You can use a set to identify distinct values:
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
Set<Integer> distinctNumbers = new LinkedHashSet<>();
System.out.println("Enter ten Numbers: ");
for (int i = 0; i < 10; i++) {
int number = input.nextInt();
distinctNumbers.add(number);
}
System.out.println("The number of distinct numbers is " + distinctNumbers.size());
System.out.print("The distinct numbers are: ");
for (Integer number : distinctNumbers){
System.out.print(number + " ");
}
}
If a value already exists in a set, it can't be added again. Arrays are not the best fit for your problem, since they must be initialized with a fixed size and you don't know how many distinct values the user will inform.
Take a look at numArray after int[] numArray = new int[10]; - it is initialized with zeros.
Ok, i got this working while loop that lets the user insert random numbers, if the number is 0 or if the loops length has been achieved then it will stop, now i have to output all the numbers that was inputed and the amount of the inputs (example 1, 2, 3 amount = 3). How do i output the array? i only get 0 from the println.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int [] a1 = new int[100];
int i = 0;
int tal;
while(true){
System.out.println("Insert number (0-end):");
tal = scan.nextInt();
if(tal == 0 || a1[i] == a1.length){
break;
}else{
tal += a1[i];
}
}//End of while
System.out.println("The inserted numbers are are: " + a1[i]);
}//
First of all, store tal in array and increment i every time you store. Finally iterate through array to print elements entered
import java.util.Scanner;
public class Tset {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int [] a1 = new int[100];
int i = 0;
int tal;
while(true){
System.out.println("Insert number (0-end):");
tal = scan.nextInt();
if(tal == 0||i>=100){
break;
}else{
a1[i]=tal;
i++;
}
}//End of while
System.out.println("The inserted numbers are are: ");
for(int j=0;j<i;j++){
System.out.println(a1[j]+"\t");
}
System.out.println("amount is: " +i);
}//
}
Use an ArrayList instead of an array to collect the number input and then iterate over it to print them use its built-in lenght method to output the amount
I am not sure what you are trying to do, but this might help.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int[] a1 = new int[100];
int i = 0;
int tal = 0;
int tmp;
do {
System.out.println("Insert number (0-end):");
tmp = scan.nextInt();
a1[i] = tmp;
tal += a1[i++];
} while (tmp != 0 && i < a1.length);
System.out.println("The inserted numbers are : ");
for (int j = 0; j < i-1; j++) {
if (j == i-2) {
System.out.print(a1[j] + ".");
} else {
System.out.print(a1[j] + ", ");
}
}
System.out.println("The sum is : " + tal);
}
Couple of issues:
You may want to put element you read into array like a1[i] = scan.nextInt(); and initializing tal as 0 and using a1[i] in if condition instead of tal.
You are not incrementing value of i and end's up overwriting the previous value.
Once you come out of loop, you just print 0th value of array which i think you entered 0 and came out of loop.
You can over come these as below:
Just after tal += a1[i]; increment value of i as:
i++;
Now to print your element, use a loop like:
System.out.print("The inserted numbers are are:");
for (int j=0; j<i; j++) {
System.out.print(" " + a1[j]);
}
System.out.println();
I have two files that I am using for my Array median code. The first file( ArrayMedian.java) is used to collect and then calculate the median, the second file is the tester file ( ArrayMedianTest.java)
I was supplied with some source code and needed to modify it accept a set range for each number in the dataset. I got that part done and the random range displays, but now when I get to he array it no longer calculates, I really can't put my finger on what is going wrong.
Another thing I am trying to do is in the ArrayMedian, is put a while loop in there to make it terminate if a '0' is input for the dataset, but it does not seem to want to work in that file, could it be due to no main in the file?
package bonus2.u06.exercise.ex3;
import java.util.Scanner;
public class ArrayMedian {
private int[] arr; // just declare array
Scanner keyboard; // shared field
// initialize keyboard and array
public void init() {
keyboard = new Scanner( System.in );
System.out.print("Enter the dataset size: ");
int size = keyboard.nextInt(); // must be odd number
arr = new int[ size ]; // instantiate
}
// Randomize the array
public void getRange() {
//System.out.println("\nYou entered: ");
System.out.print("Enter a Range: ");
int range = keyboard.nextInt();
System.out.print("array: \n");
for(int i = 0; i < arr.length; i++){
int myRnd = (int)( range * Math.random() );
System.out.print(" " + myRnd + " ");
}
}
// find the median of array
public int calcMedian() {
int half_length = arr.length/2;
for (int i = 0; i < arr.length; i++) {
int count = 0;
for (int j = 0; j < arr.length; j++) {
if (arr[i] > arr[j])
count++;
}
if (count == half_length) {
//<========= terminate this method
return arr[i];
}
}
return 0;
}
}
ArrayMedianTest:
package bonus2.u06.exercise.ex3;
public class ArrayMedianTest {
public static void main(String args[]) {
// instantiate
ArrayMedian obj = new ArrayMedian();
// execute all methods
obj.init();
obj.getRange();
int median = obj.calcMedian();
System.out.println("\nmedian : " + median);
System.out.println("\n--- done ---");
}
}
Turn out, your algorithm works perfectly fine, except in the getRange() method, you forgot to set the values of the array, so the array is an array of zeros. Here is how it should look:
public void getRange() {
//System.out.println("\nYou entered: ");
System.out.print("Enter a Range: ");
int range = keyboard.nextInt();
System.out.print("array: \n");
for(int i = 0; i < arr.length; i++){
int myRnd = (int)( range * Math.random() );
System.out.print(" " + myRnd + " ");
arr[i] = myRnd; // <-- You missed this line right here!
}
}
Also, as a recomendation, if you want to put code in stackoverflow, it has to have a spacing of four at the begining of the line plus any indenting you might use. Good luck programming!
A link to the assignment:
http://i.imgur.com/fc86hG9.png
I'm having a bit of trouble discerning how to take a series of numbers and apply them to an array without a loop. Not only that, but I'm having a bit of trouble comparing them. What I have written so far is:
import java.util.Scanner;
public class Lottery {
public static void main(String[] args) {
int userInputs[] = new int[5];
int lotteryNumbers [] = new int[5];
int matchedNumbers =0;
char repeatLottery = '\0';
Scanner in = new Scanner (System.in);
do{
System.out.println("Enter your 5 single-digit lottery numbers.\n (Use the spacebar to separate digits): ");
for(int i = 0; i <5; i++ )
userInputs[i] = in.nextInt();
System.out.println("Your inputs: ");
printArray(userInputs);
System.out.println("\nLottery Numbers: ");
readIn(lotteryNumbers);
for(int i=0; i<5; i++) {
System.out.print(lotteryNumbers[i] + " ");
}
matchedNumbers = compareArr(userInputs, lotteryNumbers);
System.out.println("\n\nYou matched " + matchedNumbers + " numbers");
System.out.println("\nDo you wish to play again?(Enter Y or N): ");
repeatLottery = in.next().charAt(0);
}
while (repeatLottery == 'Y' || repeatLottery == 'y');
}
public static void printArray(int arr[]){
int n = arr.length;
for (int i = 0; i < n; i++) {
System.out.print(arr[i] + " ");
}
}
public static void readIn(int[] List) {
for(int j=0; j<List.length; j++) {
List[j] = (int) (Math.random()*10);
}
}
public static int compareArr (int[] list1, int[] list2) {
int same = 0;
for (int i = 0; i <= list1.length-1; i++) {
for(int j = 0; j <= list2.length-1; j++) {
if (list1[i] == list2[j]) {
same++;
}
}
}
return same;
}
}
As you'll notice, I commented out the input line because I'm not quite sure how to handle it. If I have them in an array, I should be able to compare them fairly easily I think. This is our first assignment handling arrays, and I think it seems a bit in-depth for only having one class-period on it; So, please forgive my ignorance. :P
Edit:
I added a new method at the end to compare the digits, but the problem is it compares them in-general and not from position to position. That seems to be the major issue now.
your question isn't 100% clear but i will try my best.
1- i don't see any problems with reading input from user
int[] userInput = new int[5]; // maybe here you had a mistake
int[] lotterryArray = new int[5]; // and here you were declaring your arrays in a wrong way
Scanner scanner = new Scanner(system.in);
for ( int i = 0 ; i < 5 ; i++)
{
userInput[i] = scanner.nextInt();
} // this will populate your array try to print it to make sure
Edit : important in the link you shared about the assignment the compare need to check the value and location so if there are two 5 one in input one in loterry array they need to be in the same location check the assignment again
// to compare
int result = 0 ; // this will be the number of matched digits
for ( int i = 0 ; i < 5 ; i++)
{
if ( userInput[i] == loterryArray[i] )
result++
}
// in this comparsion if the digits are equale in value and location result will be incremented