Java: String formatting with placeholders

Question

I am new to Java and am from Python. In Python we do string formatting like this:

>>> x = 4
>>> y = 5
>>> print("{0} + {1} = {2}".format(x, y, x + y))
4 + 5 = 9
>>> print("{} {}".format(x,y))
4 5

How do I replicate the same thing in Java?

Answer 1

The MessageFormat class looks like what you're after.

System.out.println(MessageFormat.format("{0} + {1} = {2}", x, y, x + y));

Answer 2

Java has a String.format method that works similarly to this. Here's an example of how to use it. This is the documentation reference that explains what all those % options can be.

And here's an inlined example:

package com.sandbox;

public class Sandbox {

    public static void main(String[] args) {
        System.out.println(String.format("It is %d oclock", 5));
    }        
}

This prints "It is 5 oclock".

Answer 3

You can do this (using String.format):

int x = 4;
int y = 5;

String res = String.format("%d + %d = %d", x, y, x+y);
System.out.println(res); // prints "4 + 5 = 9"

res = String.format("%d %d", x, y);
System.out.println(res); // prints "4 5"

Answer 4

Slf4j has MessageFormatter.format() that accepts {} without the argument number, just like Python. Slf4j is a popular logging framework, but you don't have to use it for logging to use MessageFormatter.