Doubt about filling in Java Array

Question

I’m having trouble solving the following exercise:

• Create a class with a main method;
• Create an int array with 10 positions and popule using for;
• Print all array values and, for even values, display the value followed by the word "even" (use % operator to know when it is par)

First I did so, but it is giving compilation error:

public class MeuArray {
    public static void main (String[] args) {
        int[] MeuArray = new int[10];
        for (int i = 0; i < 10; i++){
            if (MeuArray[i] % 2 == 0) {
         System.out.prinln("O vetor é par:", MeuArray[i]);
        } else {
            System.out.println("O vetor é impar:" MeuArray[i]);
        }

 }
 }
}

I switched to this code and the outputs are showing the result 0:

public class MeuArray {
    public static void main (String[] args) {
        int[] MeuArray = new int[10];
        for (int i = 0; i < 10; i++){
            if (MeuArray[i] % 2 == 0) {
         System.out.println(MeuArray[i]);
        } else {
            System.out.println(MeuArray[i]);
        }

 }
 }

}

Answer 1

Your second code is not wrong, but as I mentioned in the comments, you have barely created the array, and without populating it, you are already scanning its values.

The result is always zero because an array of the primitive type int, when created, it is already filled with 0 as the starting value in all positions.

To populate an array, the logic is the same that you are already using to scan it, create a loop from position 0 to position tamanhodoarray-1 and assign values to each position, would be something similar to the below:

for(int i = 0; i < meuArray.length; i++){

    meuArray[i] = <valor que voce ira atribuir>;

}

Remember that if you use a literal value to assign the position of the array, all positions will be equal, the exercise does not speak in user input, but if allowed to use, Voce can use the Random class to generate random numbers.

Another point recalled by the user @hkotsubo is how you are concatenating values within the println(), to concatenate strings in java, if you use the symbol + and not , or space, even if you had done the spelling of the printing method correctly, would give compilation error for this reason.

The correct shape would be something like below:

System.out.println("isto é uma string literal" + variavelQualquer)

Answer 2

What do you want to put in the array? first the Array you created has 10 positions, you can fill it like this:

Meuarray[i] = i;

in this way you will fill the position i, which in the case is 0 to 9; with the very number of i.

puts this command under the for command, on top of the first if and see what happens.