Question

the following code that reads information from the file \scanner.txt\, then prints that information
assume the rest of the program and text file are written properly

try{
scanner input = new scanner(new file(\scanner.txt\));

while (input.hasnext())
{
int num = / missing code a /
string name = / missing code b /
double gpa = / missing code c /
system.out.println(num + \ \ + name + \ \ + gpa);
}
}catch(ioexception e)
{
system.out.println(\couldnt open file\);
}

option 1:
a: input.next()
b: input.next()
c: input.next()

option 2:
a: input.nextint()
b: next(input)
c: input.nextint()

option 3:
a: input.nextint()
b: input.next()
c: input.nextdouble()

which is the correct option to replace the missing code?

• option 3
• option 1
• option 2

Explanation:

🆕 New Concept Discovered: Java Scanner Token Parsing
Reading different data types from a text stream.

Step 1: Analyze the required data types

The code declares three variables with specific data types that need to be populated from the input Scanner object:

1. int num = / missing code A /; requires an integer value.
2. String name = / missing code B /; requires a text/string value.
3. double gpa = / missing code C /; requires a floating-point decimal value.

Step 2: Match variables with Java Scanner methods

To read these specific types from a Scanner object named input, we use the corresponding Scanner methods:

• For an integer (int): input.nextInt()
• For a string (String): input.next()
• For a decimal (double): input.nextDouble()

Step 3: Evaluate the options

Let's check the provided options:

• Option 1:
• A: input.next() (Incorrect: returns a String, but we need an int)
• B: input.next()
• C: input.next() (Incorrect: returns a String, but we need a double)

• Option 2:
• A: input.nextInt()
• B: next(input) (Incorrect: invalid syntax for calling a Scanner method)
• C: input.nextInt() (Incorrect: returns an int, but we need a double)

• Option 3:
• A: input.nextInt() (Correct: reads an int)
• B: input.next() (Correct: reads a String token)
• C: input.nextDouble() (Correct: reads a double)

Answer:

Option 3