diff --git a/OOP/Java/Lab/Week4/MagicSquareCheck.java b/OOP/Java/Lab/Week4/MagicSquareCheck.java
new file mode 100644
index 0000000..8b365f2
--- /dev/null
+++ b/OOP/Java/Lab/Week4/MagicSquareCheck.java
@@ -0,0 +1,55 @@
+import java.util.Scanner;
+
+class MagicSquareCheck {
+
+    public static void main(String args[]) {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter the dimension of the square matrix: ");
+        int n = sc.nextInt();
+        int a[][] = new int[n][n];
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                System.out.print(
+                    "Enter the element at (" + i + "," + j + "): "
+                );
+                a[i][j] = sc.nextInt();
+            }
+        }
+
+        // sum of the first row (to have a baseline sum)
+        int sum = 0;
+        for (int j = 0; j < n; j++) {
+            sum += a[0][j];
+        }
+
+        // rows, columns, and diagonals
+        boolean isMagicSquare = true;
+        int diag1 = 0, diag2 = 0;
+
+        for (int i = 0; i < n; i++) {
+            int rowSum = 0, colSum = 0;
+            diag1 += a[i][i];
+            diag2 += a[i][n - 1 - i];
+
+            for (int j = 0; j < n; j++) {
+                rowSum += a[i][j];
+                colSum += a[j][i];
+            }
+
+            if (rowSum != sum || colSum != sum) {
+                isMagicSquare = false;
+                break;
+            }
+        }
+
+        if (diag1 != sum || diag2 != sum) {
+            isMagicSquare = false;
+        }
+
+        if (isMagicSquare) {
+            System.out.println("The matrix is a magic square.");
+        } else {
+            System.out.println("The matrix is not a magic square.");
+        }
+    }
+}
diff --git a/OOP/Java/Lab/Week4/NonDiagEle.java b/OOP/Java/Lab/Week4/NonDiagEle.java
new file mode 100644
index 0000000..43af516
--- /dev/null
+++ b/OOP/Java/Lab/Week4/NonDiagEle.java
@@ -0,0 +1,38 @@
+import java.util.Scanner;
+
+class NonDiagEle {
+
+    public static void main(String args[]) {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter the dimension of the square matrix: ");
+        int n = sc.nextInt();
+        int a[][] = new int[n][n];
+
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                System.out.print(
+                    "Enter the element at (" + i + "," + j + "): "
+                );
+                a[i][j] = sc.nextInt();
+            }
+        }
+
+        System.out.println();
+        int nonDiagSum = 0;
+
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                if (i != j && i + j != n - 1) {
+                    System.out.print(a[i][j] + " ");
+                    nonDiagSum += a[i][j];
+                } else {
+                    System.out.print("X ");
+                }
+            }
+            System.out.println();
+        }
+
+        System.out.println();
+        System.out.println("Sum of Non-Diagonal Elements: " + nonDiagSum);
+    }
+}
diff --git a/OOP/Java/Lab/Week4/PrincipEleSum.java b/OOP/Java/Lab/Week4/PrincipEleSum.java
new file mode 100644
index 0000000..275ce95
--- /dev/null
+++ b/OOP/Java/Lab/Week4/PrincipEleSum.java
@@ -0,0 +1,34 @@
+import java.util.Scanner;
+
+class PrincipEleSum {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter the dimension of the square matrix: ");
+        int n = sc.nextInt();
+        int a[][] = new int[n][n];
+
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                System.out.print(
+                    "Enter the element at (" + i + "," + j + "): "
+                );
+                a[i][j] = sc.nextInt();
+            }
+        }
+
+        System.out.print("The Principal Elements are: [ ");
+        // Principal Element Printing and Sum
+        int sum = 0;
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                if (i == j) {
+                    System.out.print(a[i][j] + " ");
+                    sum += a[i][j];
+                }
+            }
+        }
+        System.out.println("]");
+        System.out.println("Principal Element Sum: " + sum);
+    }
+}
diff --git a/OOP/Java/Lab/Week4/SymmMatrixCheck.java b/OOP/Java/Lab/Week4/SymmMatrixCheck.java
new file mode 100644
index 0000000..9239731
--- /dev/null
+++ b/OOP/Java/Lab/Week4/SymmMatrixCheck.java
@@ -0,0 +1,41 @@
+import java.util.Scanner;
+
+class SymmMatrixCheck {
+
+    public static void main(String args[]) {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter the number of rows in the matrix: ");
+        int m = sc.nextInt();
+        System.out.print("Enter the number of colums in the matrix: ");
+        int n = sc.nextInt();
+
+        int a[][] = new int[m][n];
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                System.out.print(
+                    "Enter the element at (" + i + "," + j + "): "
+                );
+                a[i][j] = sc.nextInt();
+            }
+        }
+
+        boolean isSymmetric = true;
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                if (i != j && a[i][j] != a[j][i]) {
+                    isSymmetric = false;
+                    break;
+                }
+            }
+            if (!isSymmetric) {
+                break;
+            }
+        }
+
+        if (isSymmetric) {
+            System.out.println("The matrix is symmetric.");
+        } else {
+            System.out.println("The matrix is not symmetric.");
+        }
+    }
+}