## The challenge#

Given two arrays of strings `a1` and `a2` return a sorted array `r` in lexicographical order of the strings of `a1` which are substrings of strings of `a2`.

Example 1:

`a1 = ["arp", "live", "strong"]`

`a2 = ["lively", "alive", "harp", "sharp", "armstrong"]`

returns `["arp", "live", "strong"]`

Example 2:

`a1 = ["tarp", "mice", "bull"]`

`a2 = ["lively", "alive", "harp", "sharp", "armstrong"]`

returns `[]`

## The solution in Java code#

Option 1:

``````import java.util.ArrayList;
import java.util.List;

public class WhichAreIn {
public static String[] inArray(String[] array1, String[] array2) {
List<String> in = new ArrayList<>();
for (String a : array1)
for (String b : array2) if (b.contains(a)) in.add(a);
return in.stream().distinct().sorted().toArray(String[]::new);
}
}
``````

Option 2:

``````import java.util.stream.Stream;

public class WhichAreIn {
public static String[] inArray(String[] array1, String[] array2) {
return Stream.of(array1)
.filter(x -> Stream.of(array2).anyMatch(y -> y.contains(x)))
.distinct()
.sorted()
.toArray(String[]::new);
}
}
``````

Option 3:

``````import java.util.*;

public class WhichAreIn {
public static String[] inArray(String[] array1, String[] array2) {
List<String> result = new ArrayList<String>();
for(int i=0; i<array1.length; i++){
for(int j=0; j<array2.length; j++ ){
if(array2[j].indexOf(array1[i]) >= 0){
j =array2.length;
}
}
}
Collections.sort(result);
return result.toArray(new String[result.size()]);
}
}
``````

## Test cases to validate our solution#

``````import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

public class WhichAreInTest {
@Test
public void test1() {
String[] a = new String[]{ "arp", "live", "strong" };
String[] b = new String[] { "lively", "alive", "harp", "sharp", "armstrong" };
String[] r = new String[] { "arp", "live", "strong" };
assertArrayEquals(r, WhichAreIn.inArray(a, b));
}
@Test
public void test2() {
String[] a = new String[]{ "cod", "code", "wars", "ewar", "pillow", "bed", "phht" };
String[] b = new String[] { "lively", "alive", "harp", "sharp", "armstrong", "codewars", "cod", "code" };
String[] r = new String[] { "cod", "code", "ewar", "wars" };
assertArrayEquals(r, WhichAreIn.inArray(a, b));
}
}
``````