Can I have macros in Java source files

Question

In my program I\'m reading integers form console many times. Every time, I need to type this line.

new Scanner(System.in).nextInt(); 

I\'m

Answer 1

No. Java (the language) does not support macros of any sort.

However, certain constructs can be faked or wrapped. While the example is silly (why are you creating a new scanner each time!?!?!) the below shows how it can be achieved:

int nextInt() {
   return new Scanner(System.in).nextInt(); 
}
...
int a = nextInt();
int b = nextInt();

But much better:

Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
int b = scanner.nextInt();

Happy coding.

---

For comment:

Static methods can be called without needing an object to invoke them upon. However, in most cases one is already in an object. Consider:

public class Foo {
   static int nextIntStatic() {
     return 13;
   }

   int nextInt() {
     return 42;
   }

   void realMain () {
     // okay to call, same as this.nextInt()
     // and we are "in" the object
     int ni = nextInt();
   }

   public static void main(String[] args) {
      // okay to call, is a static method
      int nis = nextIntStatic();
      Foo f = new Foo();
      f.realMain();
   }
}

Answer 2

Use a utility class and static import.

The utility class:

package my.utils;

public class ScannerUtils {
  private ScannerUtils() {}

  public static int readInt() {
    return new Scanner(System.in).nextInt();
  }
}

Using the utility class:

package my.examples;

import static my.utils.ScannerUtils.*;

class Example {
  void foo() {
    int i = readInt();
  }
}

As others have said, you should probably cache your scanner, but that is a separate topic.