completely stumped

Question about the task

Under discussion

I have no Idea what I am doing wrong here. I think its line 32: I've tried a few different ways to no avail. Today is not my day with CodeGym :-(

1. Create an array of 20 numbers.
2. Populate it with values from the keyboard.
3. Create two arrays of 10 numbers each.
4. Copy the large array into the two small ones: half the numbers into the first small array, and the second half into the second small array.
5. Display the second small array, each value on a new line.

Requirements:

The program must create an array of 20 integers.
The program should read 20 numbers from the keyboard for the large array.
The program must create two small arrays of 10 numbers each.
The program must copy one half of the large array into the first small array, copy the second half into the second array, and then display that array on the screen.

package com.codegym.task.task07.task0705; import java.io.BufferedReader; import java.io.InputStreamReader; /* One large array and two small ones */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); int[] longArray = new int[20]; int[] shortArray1 = new int[10]; int[] shortArray2 = new int[10]; for (int i = 0; i < longArray.length; i++){ longArray[i] = Integer.parseInt(reader.readLine()); //System.out.println(longArray[i]); } //for (int j = 0; j < longArray.length/2; j++){ //shortArray1[j] = longArray[j]; //System.out.println(shortArray1[j]); //} for (int k = longArray.length/2; k < longArray.length; k++){ shortArray2[k] = longArray[k]; System.out.println(shortArray2); } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

3 March 2020, 18:54

Few things: #1 the initial value of 'k' on line 30 is being set to half the length of the long array, which means k will start at 10. On line 32 there is no 10th index of shortArray2, the indices for this array are 0-9. #2 line 33 is not printing each value out. Printing an array by using ...println(array); is going to print the hash code of the array's address in memory, not the values in the array. #3ish You still need to copy the first half of the values into the first smaller array, as I see you do in the commented out code. Un-comment that code and also make sure to remove line 26 as the task does not want you to output the values of the first small array. tip: you don't need to use different variable names for each different for loop as long as they are not contained within eachother. You can just use i (which is standard and short for 'index'). So, this is valid code:

for(int i = 0; i < something; i++) {
   // code for 1st for loop
}

for(int i = 0; i < something; i++) {
   // code for 2nd for loop
}

for(int i = 0; i < something; i++) {
   // code for 3rd for loop
}

But this will throw errors because the variable names collide in the same block of code:

for(int i = 0; i < something; i++) {
   for(int i = 0; i < something; i++) { // this will cause an error as i is already defined.
      // code for 2nd for loop
   }
}

Michael Brimage

Level 19 , Washington D.C., United States

6 March 2020, 17:51

I have revised my code to the following and still nothing: public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); int[] longArray = new int[20]; int[] shortArray1 = new int[10]; int[] shortArray2 = new int[10]; for (int i = 0; i < longArray.length; i++){ longArray[i] = Integer.parseInt(reader.readLine()); //System.out.println(longArray[i]); } for (int j = 0; j < longArray.length/2; j++){ shortArray1[j] = longArray[j]; //System.out.println(shortArray1[j]); } for (int k = 10; k < shortArray2.length; k++){ shortArray2[k] = longArray[k]; System.out.println(shortArray2[k]); } } }

Guadalupe Gagnon

Level 37 , Tampa, United States

6 March 2020, 18:10

last for loop:

/*shortArray2.length is 10. k starts at 10. This loop
will not execute*/
for (int k = 10; k < shortArray2.length; k++){
   /* and if first loop cycle k = 10. The short array has index
   0, 1, 2, 3, 4, 5, 6, 7, 8, 9
   when this next line is run:
   shortArray2[10]  = longArray[10];
   will throw an index out of range exception
   because 10 is not in the shortArray
   */
   shortArray2[k]  = longArray[k];
   System.out.println(shortArray2[k]);
}