Page 246 - IT-802_class_12
P. 246
Notes
That, since assertions reduce runtime performance, they are disabled by default. To enable
assertions at runtime, you can enable them from the command line by using the –ea option
java –eaAssertionDemo
3.7 arraY manIPuLatIon
An array is a collection of values of a similar type. In other words, an array is a group of variables accessed through a
common name. It can store a number of values of any primitive or non-primitive type. It is a composite data type. The
values stored in an array are known as array elements. In an array, the values are stored in an ordered manner and each
value has an index starting from 0 which means that the first value is stored at the 0th index, the second value is stored
at the 1st index, and so on. For example,
Array Values/Elements 5 10 8 7 1 6 4 3 11
Index 0 1 2 3 4 5 6 7 8
In the above example, you can see that value 5 is stored at 0th index, value 10 is stored at the 1st index, and the last
value 11 is stored at the 8th index. The number of elements specifies the length of the array. In the above example,
there are nine elements in the array, so the length of the array is 9.
There are several helpful methods in the Arrays class. Let’s begin by sorting an array of integers in ascending order
using the sort()method.
We import the java.util.Arrays class first. The array we need to sort is then given to the Arrays.sort() method in the
main() method.
double[] marks = {103, 144, 256.5, 346, 387.5} ;
Arrays.sort(marks);
The marks array after sorting becomes =
{103.0, 144.0, 256.5, 346.0, 387.5}.
Sorting makes it easier for us to find the lowest and highest marks obtained by a student.
To print the lowest marks, we can now write System.out.println(marks[0]);
To print the highest marks,we can write System.out.println(marks[marks.length-1]);
The same method can be used to sort an array of Strings in alphabetic order.
String[] names = {“Sarthk”,”Saumya”, ”mayank”,”mudit”,”Shiva”,”Anju”, “Savita”};
Arrays.sort(names);
Given below is a program to search a number in an array. Where:
double[] marks = {123, 651, 201, 854, 745};
int key = user input;
int index = Arrays.binarySearch(marks,key);
244 Touchpad Information Technology-XII

