Added Simple 2D Iterator Solution in java

[codingis4noobs2]

Language

Java

Challenge

Simple 2D Iterator

Closes #181

[ericwburden]

I wonder if you actually need to check the column here. Your next() function seems like it would prevent col from ever being >= the number of columns in your input array.

[ericwburden]

Nothing "wrong" with demonstrating your solution this way, but I'm going to add a comment to the PR demonstrating how to incorporate and test your code with JUnit. It'll probably look a bit wonky since it'll be using JUnit directly (instead of through an IDE or using a package manager), but it's worth taking a look at. I'm not going to ask that you change your PR to use JUnit, just take a look.

[ericwburden]

This solution works! If you wanted to use JUnit tests, we support that in the repo by leveraging the JUnit jar directly. It's included in ./resources/java along with a bash script that makes running the test a bit easier. You could incorporate the JUnit tests into your code like so:

// 2D Array Itreator

// Testing Imports
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

import java.util.Iterator;
import java.util.NoSuchElementException;

class NestedIterator<T> implements Iterator<T> {
   // clipped for brevity
}

public class Codingis4noobs2 {
    public static void main(String[] args) {
        Integer[][] array = new Integer[][] {
                { 1, 2, 3 },
                { 4, 5, 6 },
                { 7, 8, 9 }
        };
        NestedIterator<Integer> iterator = new NestedIterator<Integer>(array);
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }

    // Test case one
    @Test
    @DisplayName("Should return 1-9, in order")
    public void testCaseOne() {
        Integer[][] array = new Integer[][] {
                { 1, 2, 3 },
                { 4, 5, 6 },
                { 7, 8, 9 }
        };
        NestedIterator<Integer> iterator = new NestedIterator<Integer>(array);
        assertEquals(iterator.next(), 1);
        assertEquals(iterator.next(), 2);
        assertEquals(iterator.next(), 3);
        assertEquals(iterator.hasNext(), true);
        assertEquals(iterator.next(), 4);
        assertEquals(iterator.next(), 5);
        assertEquals(iterator.next(), 6);
        assertEquals(iterator.hasNext(), true);
        assertEquals(iterator.next(), 7);
        assertEquals(iterator.next(), 8);
        assertEquals(iterator.next(), 9);
        assertEquals(iterator.hasNext(), false);
    }
}

You can run the tests by copying .resources/java/java-test-runner.sh to your solutions directory, updating the path to the JUnit jar in that file to account for the extra nesting, and running the bash script. I'd update the test runner script like so:

#!/bin/bash

# Note: This script will execute as if in the path from which it is called
junit_jar="../../../../../resources/java/junit5-1.8.0-M1.jar"

# Runs the JUnit5 tests
run_test() {
    # Get a list of all files in the current directory that end in `.java`
    java_files=$(ls | grep java)
    
    # Compile the source and test files for this challenge, put the *.class files
    # in the 'out/' folder. Include the JUnit standalone .jar in the classpath.
    javac -d out -cp $junit_jar $java_files

    # Run the standalone JUnit testrunner with desired options, on the *.class files
    # in the 'out/' folder.
    java -jar $junit_jar \
         --classpath out \
         --scan-class-path \
         --details tree \
         --include-classname '.*'
}

# clipped for brevity

If you're wondering, this is exactly how I went about testing your solution to make sure it worked. 😁

[drkennetz]

I second what @ericwburden said. Take a look at the JUnit implementation he added to the PR.