Updated for SonarQube findings

src/main/java/com/mattrixwv/matrix/IntegerMatrix.java

@@ -1,7 +1,7 @@
 //Matrix/src/main/java/com/mattrixwv/IntegerMatrix.java
 //Mattrixwv
 // Created: 02-01-22
-//Modified: 06-29-22
+//Modified: 06-30-22
 package com.mattrixwv.matrix;
 
 
@@ -12,6 +12,7 @@ import com.mattrixwv.matrix.exceptions.InvalidCoordinatesException;
 import com.mattrixwv.matrix.exceptions.InvalidGeometryException;
 import com.mattrixwv.matrix.exceptions.InvalidRowSizeException;
 import com.mattrixwv.matrix.exceptions.InvalidScalarException;
+import com.mattrixwv.matrix.exceptions.NullMatrixException;
 
 
 public class IntegerMatrix{
@@ -141,9 +142,15 @@ public class IntegerMatrix{
 		if(row >= grid.length){
 			throw new InvalidCoordinatesException("Row cannot be greater than the number of rows");
 		}
+		else if(row < 0){
+			throw new InvalidCoordinatesException("Row cannot be less than 0");
+		}
 		else if(col >= grid[0].length){
 			throw new InvalidCoordinatesException("Column cannot be greater than the number of columns");
 		}
+		else if(col < 0){
+			throw new InvalidCoordinatesException("Column cannot be less than 0");
+		}
 
 		//Return the location in the grid
 		return grid[row][col];
@@ -162,12 +169,7 @@ public class IntegerMatrix{
 		return new IntegerMatrix(newRow);
 	}
 	public int getNumRows(){
-		if(grid == null){
-			return 0;
-		}
-		else{
-			return grid.length;
-		}
+		return grid.length;
 	}
 	public IntegerMatrix getCol(int col){
 		//Make sure the column number is valid
@@ -192,6 +194,7 @@ public class IntegerMatrix{
 			return 0;
 		}
 	}
+
 	//Sets
 	public void set(int row, int col, int value){
 		//Make sure the row number is valid
@@ -212,7 +215,10 @@ public class IntegerMatrix{
 			throw new InvalidCoordinatesException("Invalid row number " + row);
 		}
 		//Make sure the number of elements is valid
-		if(elements.length != getNumCols()){
+		if(elements == null){
+			throw new InvalidGeometryException("Row cannot be null");
+		}
+		else if(elements.length != getNumCols()){
 			throw new InvalidGeometryException(elements.length, getNumCols());
 		}
 
@@ -220,6 +226,10 @@ public class IntegerMatrix{
 		grid[row] = Arrays.copyOf(elements, elements.length);
 	}
 	public void setRow(int row, IntegerMatrix matrix){
+		//Make sure the matrix isn't null
+		if(matrix == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the matrix has a single row
 		if(matrix.getNumRows() != 1){
 			throw new InvalidGeometryException("Setting a row by Matrix requires the matrix contain a single row");
@@ -234,7 +244,10 @@ public class IntegerMatrix{
 			throw new InvalidCoordinatesException("Invalid column number " + col);
 		}
 		//Make sure the number of elements is valid
-		if(elements.length != grid.length){
+		if(elements == null){
+			throw new InvalidGeometryException("Column cannot be null");
+		}
+		else if(elements.length != grid.length){
 			throw new InvalidCoordinatesException(elements.length, grid.length);
 		}
 
@@ -244,18 +257,32 @@ public class IntegerMatrix{
 		}
 	}
 	public void setCol(int col, IntegerMatrix matrix){
+		//Make sure the matrix isn't null
+		if(matrix == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the matrix has a single column
-		if(matrix.getNumCols() != 1){
+		else if(matrix.getNumCols() != 1){
 			throw new InvalidGeometryException("Setting a column by Matrix requires the matrix contain a single column");
 		}
 
+		int[] vector = new int[matrix.getNumRows()];
+		for(int cnt = 0;cnt < matrix.getNumRows();++cnt){
+			vector[cnt] = matrix.grid[cnt][0];
+		}
+
 		//Set the column
-		setCol(col, matrix.getCol(0));
+		setCol(col, vector);
 	}
+
 	//Adds
 	public void addRow(int[] elements){
+		//Make sure the matrix isn't null
+		if(elements == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the number of columns is valid
-		if((grid.length == 0) || (getNumCols() == elements.length)){
+		else if((grid.length == 0) || (getNumCols() == elements.length)){
 			int[][] newGrid = new int[grid.length + 1][elements.length];
 			//Copy all existing data into the new grid
 			for(int row = 0;row < grid.length;++row){
@@ -271,8 +298,12 @@ public class IntegerMatrix{
 		grid[grid.length - 1] = Arrays.copyOf(elements, elements.length);
 	}
 	public void addRow(IntegerMatrix matrix){
+		//Make sure the matrix isn't null
+		if(matrix == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the matrix has a single row
-		if(matrix.getNumRows() != 1){
+		else if(matrix.getNumRows() != 1){
 			throw new InvalidGeometryException("Adding a row by Matrix requires the matrix contain a single row");
 		}
 
@@ -280,9 +311,16 @@ public class IntegerMatrix{
 		addRow(matrix.grid[0]);
 	}
 	public void addCol(int[] elements){
+		//Make sure the matrix isn't null
+		if(elements == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the number of rows is valid
 		if(grid.length == 0){
 			grid = new int[elements.length][1];
+			for(int row = 0;row < grid.length;++row){
+				grid[row][0] = elements[row];
+			}
 		}
 		else if(grid.length == elements.length){
 			//Copy all existing data into the new grid
@@ -296,17 +334,30 @@ public class IntegerMatrix{
 		}
 	}
 	public void addCol(IntegerMatrix matrix){
+		//Make sure teh matrix isn't null
+		if(matrix == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the matrix has a single column
-		if(matrix.getNumCols() != 1){
+		else if(matrix.getNumCols() != 1){
 			throw new InvalidGeometryException("Adding a column by Matrix requires the matrix contain a single column");
 		}
 
+		int[] vector = new int[matrix.getNumRows()];
+		for(int cnt = 0;cnt < matrix.getNumRows();++cnt){
+			vector[cnt] = matrix.get(cnt, 0);
+		}
+
 		//Add the column
-		addCol(matrix.getCol(0));
+		addCol(vector);
 	}
 	public IntegerMatrix appendRight(IntegerMatrix rightSide){
+		//Make sure the matrix isn't null
+		if(rightSide == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the matrices have the same number of rows
-		if(getNumRows() != rightSide.getNumRows()){
+		else if(getNumRows() != rightSide.getNumRows()){
 			throw new InvalidGeometryException("Invalid number of rows. " + rightSide.getNumRows() + " must be " + getNumRows());
 		}
 
@@ -326,8 +377,12 @@ public class IntegerMatrix{
 		return new IntegerMatrix(newGrid);
 	}
 	public IntegerMatrix appendBottom(IntegerMatrix rightSide){
+		//Make sure the matrix isn't null
+		if(rightSide == null){
+			throw new NullMatrixException();
+		}
 		//Make sure the matrices have the same number of columns
-		if(getNumCols() != rightSide.getNumCols()){
+		else if(getNumCols() != rightSide.getNumCols()){
 			throw new InvalidGeometryException("Invalid number of columns. " + rightSide.getNumCols() + " must be " + getNumCols());
 		}
 
@@ -568,6 +623,7 @@ public class IntegerMatrix{
 	}
 	private int det4(){
 		int det = 0;
+
 		//Find the row/column with the largest number of 0's
 		int zerosLocation = 0;
 		int maxNumZeros = 0;