Java Substring

Hackerrank Java Substring By Java Tech Solutionz

Problem:

Given a string, , and two indices,  and , print a substring consisting of all characters in the inclusive range from  to . You'll find the String class' substring method helpful in completing this challenge.

Input Format

The first line contains a single string denoting .
The second line contains two space-separated integers denoting the respective values of  and .

Constraints

• String  consists of English alphabetic letters (i.e., ) only.

Output Format

Print the substring in the inclusive range from  to .

Sample Input

Helloworld
3 7

Sample Output

lowo

Explanation

In the diagram below, the substring is highlighted in green:

Solutons:

public class Solution {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        String S = in.next();

        int start = in.nextInt();

        int end = in.nextInt();

        

        System.out.println(S.substring(start,end));

    }

}

Java End Of File

 Hackerrank Java End Of File Problem By Java Tech Solutionz

The challenge here is to read  lines of input until you reach EOF, then number and print all  lines of content.

Hint: Java's Scanner.hasNext() method is helpful for this problem.

Input Format

Read some unknown  lines of input from stdin(System.in) until you reach EOF; each line of input contains a non-empty String.

Output Format

For each line, print the line number, followed by a single space, and then the line content received as input.

Sample Input

Hello world
I am a file
Read me until end-of-file.

Sample Output

1 Hello world
2 I am a file
3 Read me until end-of-file.

Solution:

public class Solution {
    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner scanner = new Scanner(System.in);
        int i=0;
        while(scanner.hasNextLine()){
            System.out.println(++i + " "+scanner.nextLine());
        }
    }
}

Java static initializer block

 Hackerrank Java static initializer block By Java Tech Solutionz

Static initialization blocks are executed when the class is loaded, and you can initialize static variables in those blocks.

It's time to test your knowledge of Static initialization blocks. You can read about it here.

You are given a class Solution with a main method. Complete the given code so that it outputs the area of a parallelogram with breadth  and height . You should read the variables from the standard input.

If  or  , the output should be "java.lang.Exception: Breadth and height must be positive" without quotes.

Input Format

There are two lines of input. The first line contains : the breadth of the parallelogram. The next line contains : the height of the parallelogram.

Constraints

Output Format

If both values are greater than zero, then the main method must output the area of the parallelogram. Otherwise, print "java.lang.Exception: Breadth and height must be positive" without quotes.

Sample input 1

1
3

Sample output 1

3

Sample input 2

-1
2

Sample output 2

java.lang.Exception: Breadth and height must be positive

Solution:

static int B;
static int H;
static boolean flag = false;
static{
    Scanner scanner = new Scanner(System.in);
     B = scanner.nextInt();
     H = scanner.nextInt();
    
    if(B>0 && H>0){
        flag = true;
    }else{
        System.out.println( "java.lang.Exception: Breadth and height must be positive");
    }
}

Note:

Static Initialization Blocks
A static initialization block is a normal block of code enclosed in braces, { }, and preceded by the static keyword. Here is an example:
static {
    // whatever code is needed for initialization goes here
}
A class can have any number of static initialization blocks, and they can appear anywhere in the class body. The runtime system guarantees that static initialization blocks are called in the order that they appear in the source code.
There is an alternative to static blocks — you can write a private static method:
class Whatever {
    public static varType myVar = initializeClassVariable();
        
    private static varType initializeClassVariable() {

        // initialization code goes here
    }
}
The advantage of private static methods is that they can be reused later if you need to reinitialize the class variable