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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 x = new Scanner(System.in);
int i = x.nextInt();
double d = x.nextDouble();
x.nextLine(); //Why does this make it possible to read the string?
String s = x.nextLine(); // And not just this line?
System.out.println("String: " + s);
System.out.println("Double: " + d);
System.out.println("Int: " + i);
}
}
/*The Core Issue
When you use Scanner to read input from the console, each call to a Scanner's method (like nextInt(), nextDouble(), or nextLine()) consumes input until it reaches a delimiter (by default, whitespace characters such as spaces, tabs, and newlines). After consuming the input, it leaves the delimiter in the input buffer.
Problem Scenario
Consider the following scenario:
You read an integer using nextInt().
Then, you try to read a double using nextDouble().
Issue: Both nextInt() and nextDouble() leave a newline character (\n) in the input buffer. This happens because they stop reading input upon encountering a whitespace character, and the newline character is considered a delimiter.
Why scan.nextLine(); Is Necessary
After attempting to read a double with nextDouble(), the input buffer contains a newline character. If you were to immediately try to read a string with nextLine(), it would encounter this newline character and interpret it as the end of the input, resulting in an empty string being returned.
However, if you insert scan.nextLine(); between nextDouble() and the next nextLine(), it consumes the leftover newline character in the buffer. This way, when nextLine() is called again, it correctly waits for the user to input a new line of text, allowing it to read the string as expected.
Summary
The scan.nextLine(); call after reading an integer or a double is necessary because it consumes the leftover newline character in the input buffer, preventing it from interfering with the subsequent nextLine() call.
Without this intermediate nextLine(); call, the nextLine(); call meant to read the string would immediately encounter the newline character left behind by nextInt() or nextDouble(), leading to an empty string being read.
This pattern is a common workaround for handling input sequences involving integers, doubles, and strings in Java, ensuring that each piece of input is read correctly and in order.
*/
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Java Stdin and Stdout II
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import java.io.; import java.util.;
public class Solution {
} /*The Core Issue When you use Scanner to read input from the console, each call to a Scanner's method (like nextInt(), nextDouble(), or nextLine()) consumes input until it reaches a delimiter (by default, whitespace characters such as spaces, tabs, and newlines). After consuming the input, it leaves the delimiter in the input buffer.
Problem Scenario Consider the following scenario:
You read an integer using nextInt(). Then, you try to read a double using nextDouble(). Issue: Both nextInt() and nextDouble() leave a newline character (\n) in the input buffer. This happens because they stop reading input upon encountering a whitespace character, and the newline character is considered a delimiter.
Why scan.nextLine(); Is Necessary After attempting to read a double with nextDouble(), the input buffer contains a newline character. If you were to immediately try to read a string with nextLine(), it would encounter this newline character and interpret it as the end of the input, resulting in an empty string being returned.
However, if you insert scan.nextLine(); between nextDouble() and the next nextLine(), it consumes the leftover newline character in the buffer. This way, when nextLine() is called again, it correctly waits for the user to input a new line of text, allowing it to read the string as expected.
Summary The scan.nextLine(); call after reading an integer or a double is necessary because it consumes the leftover newline character in the input buffer, preventing it from interfering with the subsequent nextLine() call. Without this intermediate nextLine(); call, the nextLine(); call meant to read the string would immediately encounter the newline character left behind by nextInt() or nextDouble(), leading to an empty string being read. This pattern is a common workaround for handling input sequences involving integers, doubles, and strings in Java, ensuring that each piece of input is read correctly and in order. */