[java] Is there an equivalent method to C's scanf in Java?

Java has the notion of format strings, bearing a strong resemblance to format strings in other languages. It is used in JDK methods like String#format() for output conversion.

I was wondering if there an input conversion method akin to C's scanf in Java?

Not an equivalent, but you can use a Scanner and a pattern to parse lines with three non-negative numbers separated by spaces, for example:

71 5796 2489
88 1136 5298
42 420 842

Here's the code using findAll:

new Scanner(System.in).findAll("(\\d+) (\\d+) (\\d+)")
        .forEach(result -> {
            int fst = Integer.parseInt(result.group(1));
            int snd = Integer.parseInt(result.group(2));
            int third = Integer.parseInt(result.group(3));
            int sum = fst + snd + third;
            System.out.printf("%d + %d + %d = %d", fst, snd, third, sum);
        });

If one really wanted to they could make there own version of scanf() like so:

    import java.util.ArrayList;
    import java.util.Scanner;

public class Testies {

public static void main(String[] args) {
    ArrayList<Integer> nums = new ArrayList<Integer>();
    ArrayList<String> strings = new ArrayList<String>();

    // get input
    System.out.println("Give me input:");
    scanf(strings, nums);

    System.out.println("Ints gathered:");
    // print numbers scanned in
    for(Integer num : nums){
        System.out.print(num + " ");
    }
    System.out.println("\nStrings gathered:");
    // print strings scanned in
    for(String str : strings){
        System.out.print(str + " ");
    }

    System.out.println("\nData:");
    for(int i=0; i<strings.size(); i++){
        System.out.println(nums.get(i) + " " + strings.get(i));
    }
}

// get line from system
public static void scanf(ArrayList<String> strings, ArrayList<Integer> nums){
    Scanner getLine = new Scanner(System.in);
    Scanner input = new Scanner(getLine.nextLine());

    while(input.hasNext()){
        // get integers
        if(input.hasNextInt()){
            nums.add(input.nextInt());
        }
        // get strings
        else if(input.hasNext()){
            strings.add(input.next());
        }
    }
}

// pass it a string for input
public static void scanf(String in, ArrayList<String> strings, ArrayList<Integer> nums){
    Scanner input = (new Scanner(in));

    while(input.hasNext()){
        // get integers
        if(input.hasNextInt()){
            nums.add(input.nextInt());
        }
        // get strings
        else if(input.hasNext()){
            strings.add(input.next());
        }
    }
}


}

Obviously my methods only check for Strings and Integers, if you want different data types to be processed add the appropriate arraylists and checks for them. Also, hasNext() should probably be at the bottom of the if-else if sequence since hasNext() will return true for all of the data in the string.

Output:

Give me input: apples 8 9 pears oranges 5 Ints gathered: 8 9 5 Strings gathered: apples pears oranges Data: 8 apples 9 pears 5 oranges

Probably not the best example; but, the point is that Scanner implements the Iterator class. Making it easy to iterate through the scanners input using the hasNext<datatypehere>() methods; and then storing the input.

There is not a pure scanf replacement in standard Java, but you could use a java.util.Scanner for the same problems you would use scanf to solve.

You can format your output in Java as described in below code snippet.

public class TestFormat {

    public static void main(String[] args) {
      long n = 461012;
      System.out.format("%d%n", n);      //  -->  "461012"
      System.out.format("%08d%n", n);    //  -->  "00461012"
      System.out.format("%+8d%n", n);    //  -->  " +461012"
      System.out.format("%,8d%n", n);    // -->  " 461,012"
      System.out.format("%+,8d%n%n", n); //  -->  "+461,012"
   }
}

You can read more here.

THERE'S an even simpler answer

import java.io.BufferedReader;
import java.util.Scanner;

public class Main {

    public static void main(String[] args)
    {
        String myBeautifulScanf = new Scanner(System.in).nextLine();
        System.out.println( myBeautifulScanf );

    }
}

Java always takes arguments as a string type...(String args[]) so you need to convert in your desired type.

• Use Integer.parseInt() to convert your string into Interger.
• To print any string you can use System.out.println()

Example :

  int a;
  a = Integer.parseInt(args[0]);

and for Standard Input you can use codes like

  StdIn.readInt();
  StdIn.readString();