Taking text apart

Input often packs several values into one line of text. A program cuts the line into parts, turns the parts that are numbers into numbers, and asks questions about the parts that are words.

The tools

Words on a line

Chess players write down their games move by move. Each move is a short code, such as Nf3 (a knight moves to the square f3). An x in a move means it captures a piece, and a + at the end means it puts the other king in check. Here are the first moves of a game, one code for each player's move, separated by spaces:

String moves = "e4 e5 Nf3 Nc6 Bb5 a6 Bxc6 dxc6";
String[] parts = moves.split(" ");
int captures = 0;
for (String move : parts) {
    if (move.contains("x")) {
        captures++;
    }
}
System.out.println(parts.length + " moves, " + captures + " captures");
System.out.println("Last move: " + parts[parts.length - 1]);

8 moves, 2 captures
Last move: dxc6

• split(" ") gives an array of Strings, one per move, and a for-each loop goes through them.
• contains("x") asks whether the letter appears anywhere in the move. It counts capital letters apart from small ones: contains("X") would find nothing here.
• The last part is at the index parts.length - 1.

A line of comma-separated values

A climbing gym's member list has one line per member: the name, the age and the number of visits this month, separated by commas. Someone typed a space after each comma. The gym calls a member with 8 visits or more in a month a regular.

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String[] parts = scanner.nextLine().split(",");
        String name = parts[0].trim();
        int age = Integer.valueOf(parts[1].trim());
        int visits = Integer.valueOf(parts[2].trim());
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Visits: " + visits);
        System.out.println("Regular: " + (visits >= 8));
    }
}

Mira Koski, 34, 12

Name: Mira Koski
Age: 34
Visits: 12
Regular: true

• The parts are Strings, even when they hold digits. Integer.valueOf turns them into ints. Without it, parts[2].trim() + 1 would join the texts and give 121.
• split(",") cuts only at the commas, so the second part is " 34", with the space in front. Integer.valueOf(" 34") throws a NumberFormatException, and trim() removes the space first (module 16).
• A line with fewer than three parts would crash at parts[2] with an ArrayIndexOutOfBoundsException. When lines can be broken, check parts.length first and skip the line (module 29).