Kylian Murphy - 6 months ago 26

Java Question

What I am trying to do is use one method to generate 30 random numbers from 0-15 and then another method to count how many times each number prints and put it in a second array. Each position in the second array corresponds to the number in the array it is. if i = [0] and 0 shows up 3 times, it should be 3 and so on.

So far, I have gotten this. What seems to be happening is that it counts the number of times 15 shows up (The last number of the array). Though I could be wrong. I don't see what I'm doing wrong. There must be something wrong with my logic.

`import java.util.Arrays;`

public class FrequencyOfNumbers {

public static void main(String[]args){

System.out.println(Arrays.toString(randomNums()));

System.out.println(Arrays.toString(sortedNums(randomNums())));

}

public static int[] randomNums (){

int[] random = new int[30];

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

double randNum = Math.random() * 16;

random[i] = (int)randNum;

}

return random;

}

public static int[] sortedNums(int[] sort){

int[] numVals = new int[15];

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

{

for(int j=0;j<sort.length;j++)

{

if(sort[j] == numVals[i])

{

numVals[i]++;

}

}

}

return numVals;

}

}

Example output I'm receiving:

`[5, 15, 0, 5, 4, 10, 4, 11, 5, 13, 13, 8, 9, 9, 10, 6, 0, 9, 10, 12, 3, 7, 4, 9, 4, 11, 9, 15, 10, 7]`

[2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]

Answer

You have some problems in the code:

Don't call

`randomNums()`

twice. Otherwise you don't count the right frequency. It will generate different arrays.If you want to keep numbers from 0 to 15, you should allocate 16 elements for

`numVals`

.You don't need an inner

`for`

loop when you count the appearances. Just consider all the numbers, take their values, and increment the number of appearances.

Try this:

```
public static void main(String[] args) {
int[] randomNumbers = randomNums();
System.out.println(Arrays.toString(randomNumbers));
System.out.println(Arrays.toString(sortedNums(randomNumbers)));
}
public static int[] randomNums() {
int[] random = new int[30];
for (int i = 0; i < random.length; i++) {
random[i] = (int) (Math.random() * 16);
}
return random;
}
public static int[] sortedNums(int[] sort) {
int[] numVals = new int[16];
for (int j = 0; j < sort.length; j++) {
numVals[sort[j]]++;
}
return numVals;
}
```

A possible output:

```
[8, 6, 5, 12, 12, 9, 15, 6, 7, 9, 15, 3, 6, 7, 3, 8, 6, 3, 15, 8, 12, 4, 7, 12, 2, 15, 6, 5, 4, 5]
[0, 0, 1, 3, 2, 3, 5, 3, 3, 2, 0, 0, 4, 0, 0, 4]
```