combine two array string to make a list

Question

I am working on my own personal app for minecraft. I would forget what recipe I need, and I would just search, and have it display the recipe.

Now, I have the list and search function with it being alphabetical. Now I am manually adding images, and everything else I need. BUT I think it would be more efficient if I had a array string like this

String test1[] = { "diamond", "Iron", "Leather" };
String test2[] = { "Leggings", "Boots", "Helmet", "Chestplate" }

and in my list view I want the end result to be like this.

Diamond leggings
Diamond boots
Diamond Helmet
Diamond Chestplate
Iron Leggings
...
...
Gold Leggings
...
...
...

What would I need to do to achieve that? I think it would be ineffecient if I did it like this test3.add("Diamond Chestplate") test3.add("Diamond boots") etc.. .. ...

and end up having big list instead where I can combine them.

• Dawood ibn Kareem: Try a couple of nested loops. Comment again if you get stuck.

Answer 1

Use 2 nested for loops to merge the arrays:

 String test1[] = {"Diamond", "Iron", "Leather"};
 String test2[] = {"Leggings", "Boots", "Helmet", "Chestplate"};
 List<String> merged = new ArrayList<String>();
 for (String str1 : test1) {
 for (String str2 : test2)
 merged.add(str1 + " " + str2);
 }
 System.out.println(merged);

• andyADD: Thanks for the answer, but Elliott also answered with nested, too.

Answer 2

If I understand your question, you could do with nested For-Each Loop(s) like

String test1[] = { "Diamond", "Iron", "Leather" };
String test2[] = { "Leggings", "Boots", "Helmet", "Chestplate" };
List<String> al = new ArrayList<>();
for (String i : test1) {
 for (String j : test2) {
 StringBuilder sb = new StringBuilder(i);
 sb.append(' ').append(j);
 al.add(sb.toString());
 }
}
System.out.println(al);

• andyADD: thank you this is perfect, I will need this in the future and will be able to compile my list with a lot less line of code. Thanks!

Answer 3

I am curious to know that If, I can achieve it in a single loop. How to do it, and finally I have done it.

private static String test1[] = {"Diamond", "Iron", "Leather"};
private static String test2[] = {"Leggings", "Boots", "Helmet", "Chestplate"};
public static void doInSingleLoop() {
 int maxLength = test1.length * test2.length;
 List<String> al = new ArrayList<String>();
 for (int i = 0; i < maxLength; i++) {
 String t1 = test1[i / test2.length];
 String t2 = test2[i % test2.length];
 StringBuilder sb = new StringBuilder(t1);
 sb.append(' ').append(t2);
 al.add(sb.toString());
 }
 System.out.println(al);
 }

• howrad: This required a change from String t1 = test1[i / test1.length]; to String t1 = test1[i / test2.length];, or it would produce an incorrect result and an ArrayIndexOutOfBoundsException. Edit submitted.
• howrad: Also, even when using a single loop, it's still an O(N^2) problem, so this answer is probably not any more efficient than a nested loop. But it is an important exercise.

Answer 4

Check below example.

public static void main(String[] args) { 
	String firstNameArr[] = { "diamond", "Iron", "Leather" };
 String lastNameArr[] = { "Leggings", "Boots", "Helmet"};
 List<String> fullNameList = new ArrayList<String>();
 
 for (String firstname : firstNameArr) {
 	for(String lastName : lastNameArr){
 		fullNameList.add((firstname+" "+lastName));
 	} 
 } 
}

• howrad: This does not produce the correct result. The output of this code is: diamond Leggings<br> Iron Boots<br> Leather Helmet