How to Correct the Mistakes of the Character Recognition Software in Java

The challenge

Character recognition software is widely used to digitise printed texts. Thus the texts can be edited, searched and stored on a computer.

When documents (especially pretty old ones written with a typewriter), are digitised character recognition softwares often make mistakes.

Your task is correct the errors in the digitised text. You only have to handle the following mistakes:

• S is misinterpreted as 5
• O is misinterpreted as ``
• I is misinterpreted as 1

The test cases contain numbers only by mistake.

The solution in Java code

public class Correct {
  public static String correct(String string) {
    return string.replace("5", "S").replace("0", "O").replace("1", "I");
  }
}

Test cases to validate our Java code

import org.junit.Test;
import static org.junit.Assert.assertEquals;
import org.junit.runners.JUnit4;
import org.apache.commons.lang3.RandomStringUtils;

public class SolutionTest {
    @Test
    public void testFixed() {
        assertEquals("IF-RUDYARD KIPLING", Correct.correct(Correct.correct("1F-RUDYARD K1PL1NG")));
        assertEquals("ROBERT MERLE - THE DAY OF THE DOLPHIN", Correct.correct(Correct.correct("R0BERT MERLE - THE DAY 0F THE D0LPH1N")));
        assertEquals("RICHARD P. FEYNMAN - THE FEYNMAN LECTURES ON PHYSICS", Correct.correct(Correct.correct("R1CHARD P. FEYNMAN - THE FEYNMAN LECTURE5 0N PHY51C5")));
        assertEquals("RICHARD P. FEYNMAN - STATISTICAL MECHANICS", Correct.correct(Correct.correct("R1CHARD P. FEYNMAN - 5TAT15T1CAL MECHAN1C5")));
        assertEquals("STEPHEN HAWKING - A BRIEF HISTORY OF TIME", Correct.correct(Correct.correct("5TEPHEN HAWK1NG - A BR1EF H15T0RY 0F T1ME")));
        assertEquals("STEPHEN HAWKING - THE UNIVERSE IN A NUTSHELL", Correct.correct(Correct.correct("5TEPHEN HAWK1NG - THE UN1VER5E 1N A NUT5HELL")));
        assertEquals("ERNEST HEMINGWAY - A FARWELL TO ARMS", Correct.correct(Correct.correct("ERNE5T HEM1NGWAY - A FARWELL T0 ARM5")));
        assertEquals("ERNEST HEMINGWAY - FOR WHOM THE BELL TOLLS", Correct.correct(Correct.correct("ERNE5T HEM1NGWAY - F0R WH0M THE BELL T0LL5")));
        assertEquals("ERNEST HEMINGWAY - THE OLD MAN AND THE SEA", Correct.correct(Correct.correct("ERNE5T HEM1NGWAY - THE 0LD MAN AND THE 5EA")));
        assertEquals("J. R. R. TOLKIEN - THE LORD OF THE RINGS", Correct.correct(Correct.correct("J. R. R. T0LK1EN - THE L0RD 0F THE R1NG5")));
        assertEquals("J. D. SALINGER - THE CATCHER IN THE RYE", Correct.correct(Correct.correct("J. D. 5AL1NGER - THE CATCHER 1N THE RYE")));
        assertEquals("J. K. ROWLING - HARRY POTTER AND THE PHILOSOPHER'S STONE", Correct.correct(Correct.correct("J. K. R0WL1NG - HARRY P0TTER AND THE PH1L050PHER'5 5T0NE")));
        assertEquals("J. K. ROWLING - HARRY POTTER AND THE CHAMBER OF SECRETS", Correct.correct(Correct.correct("J. K. R0WL1NG - HARRY P0TTER AND THE CHAMBER 0F 5ECRET5")));
        assertEquals("J. K. ROWLING - HARRY POTTER AND THE PRISONER OF Azkaban", Correct.correct(Correct.correct("J. K. R0WL1NG - HARRY P0TTER AND THE PR150NER 0F Azkaban")));
        assertEquals("J. K. ROWLING - HARRY POTTER AND THE GOBLET OF FIRE", Correct.correct(Correct.correct("J. K. R0WL1NG - HARRY P0TTER AND THE G0BLET 0F F1RE")));
        assertEquals("J. K. ROWLING - HARRY POTTER AND THE ORDER OF PHOENIX", Correct.correct(Correct.correct("J. K. R0WL1NG - HARRY P0TTER AND THE 0RDER 0F PH0EN1X")));
        assertEquals("J. K. ROWLING - HARRY POTTER AND THE HALF-BLOOD PRINCE", Correct.correct(Correct.correct("J. K. R0WL1NG - HARRY P0TTER AND THE HALF-BL00D PR1NCE")));
        assertEquals("J. K. ROWLING - HARRY POTTER AND THE DEATHLY HALLOWS", Correct.correct(Correct.correct("J. K. R0WL1NG - HARRY P0TTER AND THE DEATHLY HALL0W5")));
        assertEquals("URSULA K. LE GUIN - A WIZARD OF EARTHSEA", Correct.correct(Correct.correct("UR5ULA K. LE GU1N - A W1ZARD 0F EARTH5EA")));
        assertEquals("URSULA K. LE GUIN - THE TOMBS OF ATUAN", Correct.correct(Correct.correct("UR5ULA K. LE GU1N - THE T0MB5 0F ATUAN")));
        assertEquals("URSULA K. LE GUIN - THE FARTHEST SHORE", Correct.correct(Correct.correct("UR5ULA K. LE GU1N - THE FARTHE5T 5H0RE")));
        assertEquals("URSULA K. LE GUIN - TALES FROM EARTHSEA", Correct.correct(Correct.correct("UR5ULA K. LE GU1N - TALE5 FR0M EARTH5EA")));  
    }
    
    @Test
    public void testRandom() {
        for(int i = 0; i < 100; i++) {
          String string = RandomStringUtils.randomAlphanumeric(100);
          assertEquals(CorrectSolution.correct(string), Correct.correct(string));
        }
    }
}

class CorrectSolution {
  public static String correct(String string) {
    return string.replaceAll("1", "I").replaceAll("0", "O").replaceAll("5", "S");
  }
}