GETTING INPUT

SCENARIO 2A
GETTING n DATA SPACE DELIMITED ON A SINGLE LINE (n is known before run-time)

This is a common situation. In Java, this is very simple if the data is separated by spaces because the Scanner methods next(), nextInt() and nextDouble() all recognize spaces in the same was as they recognize a new line.

SAMPLE INPUT 1 (n = 7)

1 4 4 5 2 4 5

SAMPLE INPUT 2 (n = 4)

4.1 3.4 3.0 1.8

SAMPLE INPUT 3 (n = 3)

apple,orange,banana

Here are some examples:

EXAMPLE 1 - INTEGERS

Below is an example where a line of 6 integers separated by a space are entered as input. So n is 6. We place each integer into its own element inside an int array named data.

Students sometimes struggle with this because the user only does data entry once but the Scanner still reads it 6 times. This is because a Scanner only gives the user an opportunity to enter data if the input stream is empty.

import java.util.Arrays;

import java.util.Scanner;

public class InputBasics

{

public static void main(String[] args)

{

Scanner scr = new Scanner(System.in);

int n = 6;

int[] data = new int[n];

for (int i=0; i<n; i++)

{

data[i] = scr.nextInt(); //read next int in the stream

}

//process the data array here

System.out.println(Arrays.toString(data));

}

}

SAMPLE EXECUTION

3 4 5 2 30 4

[3, 4, 5, 2, 30, 4]

EXAMPLE 2 – STRINGS

The following example does the same as the example above but for an input line of 4 Strings. So n is 4.

Note that because we want to recognize the space as a separator, we cannot use scr.nextLine() here.

import java.util.Arrays;

import java.util.Scanner;

public class InputBasics

{

public static void main(String[] args)

{

Scanner scr = new Scanner(System.in);

int n = 4;

String[] data = new String[n];

for (int i=0; i<n; i++)

{

data[i] = scr.next(); //read next String in the stream

}

//process the data array here

System.out.println(Arrays.toString(data));

}

}

SAMPLE EXECUTION

pat bat rat cat

[pat, bat, rat, cat]

EXAMPLE 2B – ALTERNATIVE OPTION

In this example, our program actually uses scr.nextLine() to read in the entire line all at once. This should leave us in a difficult situation because now we have to separate all the data that is in the line. However, this easy using the String method split which will automatically generate a String array for us! Pretty sweet solution!

Note: What is nice about this solution is that it could work with other forms of delimitation such as data delimited by commas or dashes.

import java.util.Arrays;

import java.util.Scanner;

public class InputBasics

{

public static void main(String[] args)

{

Scanner scr = new Scanner(System.in);

String line = scr.nextLine(); //read entire line

String[] data = line.split(" ");

//process the data array here

System.out.println(Arrays.toString(data));

}

}

SAMPLE EXECUTION

dog cat purple

[dog, cat, purple]