Please explain the following methods in details

public class Task1 {   public static void main(String[] args) {     double[] nums1d = {1, 3};     double[][] nums1 = {{1, 2}, {3, 4, 5}, {6}};     double[][] nums2 = {{4, 6}, {12, 4, 5}, {6}};     String str = "abc";     String[] str2 = {"Hello", "World"};     String[][] str3 = {{"Hello", "World"}, {"Welcome", "to", "Java"}}; } /**   * This method adds a number to each element of a 2d array   *   * @param nums1 {{1,2},{3,4,5},{6}}   * @param value {5}   * @return added value(5) to nums1 [[6.0, 7.0], [8.0, 9.0, 10.0], [11.0]]   */   public static double[][] addValueToTwoDArray(double[][] nums1,       double value) {     for (double[] nums : nums1) {       for (int i = 0; i < nums.length; i++) {         nums[i] += value;       }     }     return nums1;   }   /**   * This method adds two 2d double arrays   *   * @param nums1 {6.0, 7.0}, {8.0, 9.0, 10.0},{11.0}   * @param nums2 {{4,6},{12,4,5},{6}}   * @return new array(nums1+nums2) [[10.0, 13.0], [20.0, 13.0, 15.0], [17.0]]   */   public static double[][] addArrays(double[][] nums1, double[][] nums2) {     double[][] newArray = new double[nums1.length][];     for (int i = 0; i < newArray.length; i++) {       double[] array1row = nums1[i];       double[] array2row = nums2[i];       double[] newrow = new double[array1row.length];       for (int j = 0; j < newrow.length; j++) {         newrow[j] = array1row[j] + array2row[j];       }       newArray[i] = newrow;     }     return newArray;   }   /**   * This method appends a 1d double array to a 2d double array as a new row   *   * @param nums1 {6.0, 7.0}, {8.0, 9.0, 10.0},{11.0}   * @param nums1d {1,3}   * @return appends 1d and 2d arrays [[6.0, 7.0], [8.0, 9.0, 10.0],[11.0]   * [1.0, 3.0]]   */   public static double[][] app1DArray(double[][] nums1, double[] nums1d) {     double[][] result = Arrays.copyOf(nums1, nums1.length + 1);     result[nums1.length] = nums1d;     return result;   }   /**   * This method appends a 2d double array under another 2d double array   *   * @param nums1 [[6.0, 7.0], [8.0, 9.0, 10.0], [11.0]]   * @param nums2 {{4,6},{12,4,5},{6}}   * @return new array [[6.0, 7.0], [8.0, 9.0, 10.0], [11.0], [4.0, 6.0]   * [12.0, 4.0, 5.0], [6.0]]   */   public static double[][] app2DArray(double[][] nums1, double[][] nums2) {     double[][] app = new double[nums1.length + nums2.length][];     System.arraycopy(nums1, 0, app, 0, nums1.length);     System.arraycopy(nums2, 0, app, nums1.length, nums2.length);     return app;   }   /**   * This method appends a 2d double array at the right of another 2d array   *   * @param nums1 [[6.0, 7.0], [8.0, 9.0, 10.0], [11.0]]   * @param nums2 {{4,6},{12,4,5},{6}}   * @return new array [[6.0, 7.0, 4.0, 6.0], [8.0, 9.0, 10.0, 12.0, 4.0, 5.0]   * [11.0, 6.0]]   */   public static double[][] appendRight(double[][] nums1, double[][] nums2) {     // defining new array by increasing length by size of two arrays     double[][] newArray = new double[nums1.length][];     // adding first array to the new array     for (int i = 0; i < newArray.length; i++) {       double[] array1row = nums1[i];       double[] array2row = nums2[i];       double[] newRow = new double[array1row.length + array2row.length];       for (int j = 0; j < array1row.length; j++) {         newRow[j] = array1row[j];       }       for (int j = 0; j < array2row.length; j++) {         newRow[array1row.length + j] = array2row[j];       }       newArray[i] = newRow;     }     return newArray;   }   /**   * This method removes a row from a 2d array   *   * @param nums1 [[6.0, 7.0], [8.0, 9.0, 10.0], [11.0]]   * @param index {0}   * @return newArray [8.0, 9.0, 10.0], [11.0]]   */   public static double[][] removeRow(double[][] nums1, int index) {     double[][] newArray;     if (index < 0 || index >= nums1.length) {       newArray = new double[nums1.length][];     } else {       newArray = new double[nums1.length - 1][];     }     int newIndex = 0;     for (int i = 0; i < nums1.length; i++) {       // if if the idx is invalid, returns the orignal array       if (i != index) {         newArray[newIndex] = nums1[i];         newIndex++;       }     }     return newArray;   } }