JAVA Topic 4: Arrays

You can declare, create and initialize array in one step

double [ ] myList = {1.9, 2.9, 3.4, 3.5}; This shorthand syntax must be in one statement

Finding the largest element

double max = myList[0]; for (int i = 1; i < myList.length; i++) { if (myList[i] > max) max = myLIst[i]; }

declaring array variables

datatype[ ] arrayRefVar; e.g. double [ ] myList;

Ragged arrays

Each for in a two dimensional array is itself an array. So, the rows can have different lengths. Such an array is known as ragged array. For example, int [ ] [ ] matrix = { {1, 2, 3, 4, 5,}, {2, 3, 4, 5}, {3, 4, 5}, {4, 5}, {5} },

The arraycopy utility making source array equal to target array

System.arraycopy(sourceArray, 0, targetArray, 0, sourceArray.length);

Once an array is created, its size cannot be changed.

You can find the size of an array using arrayRefVar.length e.g. myList.length returns 10

Creating arrays

arrayRefVar = new datatype [arraySize]; e.g. myList = new double [10] myList [0] references the first element in the array myList [0] references the last element in the array

Initializing arrays with input values

java.util.Scanner input = new java.util.Scanner (System.in); System.out.print("Enter" + myList.length + "values: "); for (int i = 0; i < myList.length; i++) myList[i] = input.nextDouble();