Java Program to Implement Sparse Matrix

This Java Program is to Implement Sparse Matrix.In the subfield of numerical analysis, a sparse matrix is a matrix populated primarily with zeros (Stoer & Bulirsch 2002, p. 619) as elements of the table. By contrast, if a larger number of elements differ from zero, then it is common to refer to the matrix as a dense matrix. The fraction of zero elements (non-zero elements) in a matrix is called the sparsity (density).

Here is the source code of the Java Program to Implement Sparse Matrix. The Java program is successfully compiled and run on a Linux system. The program output is also shown below.

```
public class SparseMatrix
```
```
{
```
```
    private int N;
```
```
    private SparseArray sparsearray[];
```
```
 
```
```
    public SparseMatrix(int N)
```
```
    {
```
```
        this.N = N;
```

        sparsearray = new SparseArray[N];

        for (int index = 0; index < N; index++)

```
        {
```

            sparsearray[index] = new SparseArray(N);

```
        }
```
```
    }
```
```
 
```

    public void store(int rowindex, int colindex, Object value)

```
    {
```

        if (rowindex < 0 || rowindex > N)

            throw new RuntimeException("row index out of bounds");

        if (colindex < 0 || colindex > N)

            throw new RuntimeException("col index out of bounds");

        sparsearray[rowindex].store(colindex, value);

```
    }
```
```
 
```

    public Object get(int rowindex, int colindex)

```
    {
```

        if (rowindex < 0 || colindex > N)

            throw new RuntimeException("row index out of bounds");

        if (rowindex < 0 || colindex > N)

            throw new RuntimeException("col index out of bounds");

```
 
```

        return (sparsearray[rowindex].fetch(colindex));

```
    }
```
```
 
```

    public static void main(String... arg)

```
    {
```

        Integer[][] iarray = new Integer[3][3];

```
        iarray[0][0] = 1;
```
```
        iarray[0][1] = null;
```
```
        iarray[0][2] = 2;
```
```
        iarray[1][0] = null;
```
```
        iarray[1][1] = 3;
```
```
        iarray[1][2] = null;
```
```
        iarray[2][0] = 4;
```
```
        iarray[2][1] = 6;
```
```
        iarray[2][2] = null;
```
```
 
```

        SparseMatrix sparseMatrix = new SparseMatrix(3);

        for (int rowindex = 0; rowindex < 3; rowindex++)

```
        {
```

            for (int colindex = 0; colindex < 3; colindex++)

```
            {
```

                sparseMatrix.store(rowindex, colindex,

                iarray[rowindex][colindex]);

```
            }
```
```
        }
```

        System.out.println("the sparse Matrix is ");

        for (int rowindex = 0; rowindex < 3; rowindex++)

```
        {
```

            for (int colindex = 0; colindex < 3; colindex++)

```
            {
```

                System.out.print(sparseMatrix.get(rowindex, colindex) + "\t");

```
            }
```
```
            System.out.println();
```
```
        }
```
```
    }
```
```
}
```
```
 
```
```
class List
```
```
{
```
```
    private int index;
```
```
    private Object value;
```
```
    private List nextindex;
```
```
 
```
```
    public List(int index)
```
```
    {
```
```
        this.index = index;
```
```
        nextindex = null;
```
```
        value = null;
```
```
    }
```
```
 
```
```
    public List()
```
```
    {
```
```
        index = -1;
```
```
        value = null;
```
```
        nextindex = null;
```
```
    }
```
```
 
```

    public void store(int index, Object value)

```
    {
```
```
        List current = this;
```
```
        List previous = null;
```
```
 
```
```
        List node = new List(index);
```
```
        node.value = value;
```

        while (current != null && current.index < index)

```
        {
```
```
            previous = current;
```

            current = current.nextindex;

```
        }
```
```
        if (current == null)
```
```
        {
```
```
            previous.nextindex = node;
```
```
        }
```
```
        else
```
```
        {
```
```
            if (current.index == index)
```
```
            {
```

                System.out.println("DUPLICATE INDEX");

```
                return;
```
```
            }
```
```
            previous.nextindex = node;
```
```
            node.nextindex = current;
```
```
        }
```
```
        return;
```
```
    }
```
```
 
```
```
    public Object fetch(int index)
```
```
    {
```
```
        List current = this;
```
```
        Object value = null;
```

        while (current != null && current.index != index)

```
        {
```

            current = current.nextindex;

```
        }
```
```
        if (current != null)
```
```
        {
```
```
            value = current.value;
```
```
        }
```
```
        else
```
```
        {
```
```
            value = null;
```
```
        }
```
```
        return value;
```
```
    }
```
```
 
```
```
    public int elementCount()
```
```
    {
```
```
        int elementCount = 0;
```

        for (List current = this.nextindex; (current != null); current = current.nextindex)

```
        {
```
```
            elementCount++;
```
```
        }
```
```
        return elementCount;
```
```
    }
```
```
}
```
```
 
```
```
public class SparseArray
```
```
{
```
```
    private List start;
```
```
    private int index;
```
```
 
```
```
    SparseArray(int index)
```
```
    {
```
```
        start = new List();
```
```
        this.index = index;
```
```
    }
```
```
 
```

    public void store(int index, Object value)

```
    {
```

        if (index >= 0 && index < this.index)

```
        {
```
```
            if (value != null)
```

                start.store(index, value);

```
        } else
```
```
        {
```

            System.out.println("INDEX OUT OF BOUNDS");

```
        }
```
```
    }
```
```
 
```
```
    public Object fetch(int index)
```
```
    {
```

        if (index >= 0 && index < this.index)

```
            return start.fetch(index);
```
```
        else
```
```
        {
```

            System.out.println("INDEX OUT OF BOUNDS");

```
            return null;
```
```
        }
```
```
    }
```
```
 
```
```
    public int elementCount()
```
```
    {
```
```
        return start.elementCount();
```
```
    }
```
```
}
```

$javac SparseMatrix.java
$java SparseMatrix
the sparse Matrix is 
1    null  2	
null 3     null	
4    6     null

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