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.

Try a couple of nested loops. Comment again if you get stuck. — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Nov 6, 2014 at 3:32

howrad · Accepted Answer · 2014-11-09 12:16:31Z

2

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);

edited Nov 9, 2014 at 12:16

howrad

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answered Nov 6, 2014 at 3:52

Amar

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1 Comment

andyADD Over a year ago

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

Elliott Frisch · Accepted Answer · 2014-11-06 03:35:15Z

1

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);

answered Nov 6, 2014 at 3:35

Elliott Frisch

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1 Comment

andyADD Over a year ago

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!

howrad · Accepted Answer · 2014-11-06 19:40:50Z

1

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);
    }

edited Nov 6, 2014 at 19:40

howrad

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answered Nov 6, 2014 at 4:49

VikasGoyal

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2 Comments

howrad Over a year ago

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 Over a year ago

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.

Isuru Jayakantha · Accepted Answer · 2014-11-07 03:38:00Z

-1

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));
    	} 
    } 
}

edited Nov 7, 2014 at 3:38

answered Nov 6, 2014 at 4:15

Isuru Jayakantha

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1 Comment

howrad Over a year ago

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

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