Java put matrix element in array

Question

i was trying to compare 2 variables in java but it gives me error and i cant figure it out.

I am reading matrix element then put it in temp then put that temp variable in an array. but it gives error when I try to put matrix element in temp and when I compare elements. error: array required, but float found. Anyone knows how to correct this ?

    public float[] toSortedArray()
  {
    float b[];
    float temp;
    int index=0;
    for(int i=1; i<=m; i++)
    {
      for(int j=1; j<=n; j++)
      {
        temp=a[m][n];
        b[index++]=temp;
      }
    }
      Arrays.sort(b);

        System.out.print("[");
      for(int z=0; z<(m*n)-1; z++)
      {
        System.out.print(b[z]+", ");
      } 
      System.out.print(b[(m*n)-1]+"]\n");
  }

What is a? It is never declared. Is it a field? Also please specify in which line the error occurs. Also use proper indentation. Finally, if you used an IDE such as Eclipse, you would quickly find most errors. Another one is that your method is missing a return statement. — Ingo Bürk
– Ingo Bürk, Commented Oct 21, 2014 at 16:43
m and n are also not declared in this snippet. I also think you want to use i and j inside the loop to access the "matrix". There is a lot wrong with this code. — Ingo Bürk
– Ingo Bürk, Commented Oct 21, 2014 at 16:44
this is just little part of my code i have declared m and n in the class as a private members. i tried also in eclipse but error is the same. it occurs here: temp=a[m][n]; b[index++]=temp; — e8oo
– e8oo, Commented Oct 21, 2014 at 16:51
Of course the error is the same. But with an IDE, you will get useful, instant feedback and it will automatically indent the code correctly etc. For the error, look into the answers you have received so far. — Ingo Bürk
– Ingo Bürk, Commented Oct 21, 2014 at 16:53

SMA · Accepted Answer · 2014-10-21 16:59:05Z

2

There are several things needed in this:

Pass on the m, n parameter along with original 2D array like
```
public float[] toSortedArray(float[][] a, int m, int n)
```
define b array as
```
float b[] = new float[m*n];
```
In for loop (one within i and j var) (both loop should start with 0) use
```
temp=a[i][j];
```

instead of

    temp=a[m][n];

At the end return b.
```
return b;
```

edited Oct 21, 2014 at 16:59

answered Oct 21, 2014 at 16:44

SMA

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5 Comments

Ingo Bürk Over a year ago

Since m and n are probably supposed to be the dimensions of a, I don't think passing them is necessary. Just use a.length and a[i].length. However, the loop needs to be shifted by 1 because arrays in Java are 0-based.

SMA Over a year ago

if a is null then or just initialised like float a[][] = new float[5][];?

e8oo Over a year ago

thank you it worked when i declared public float[] toSortedArray(float[][] a, int m, int n) but in main function toSortedArray() is empty and it gives another error because ublic float[] toSortedArray(float[][] a, int m, int n) and toSortedArray() are not same. Also i cant change main function. are there any other way to correct this ?

SMA Over a year ago

how are you going to get a[][] array and value of m and n? that would be the best place to call this method from like myclass.toSortedArray(a, m, n);

e8oo Over a year ago

float[] arr = fm.toSortedArray(); i didnt do main its given in the example itself.

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