Get value of String Integer from created string

Question

So say if I had a series of String Integers with name, i: i1 , i2 , i3 etc but wanted to make up each name with a combination of a String and an Integer like:

String i1 = "abc";
String i2 = "bca";
String i3 = "cba";

for (int i = 1; i <= 3; i++) {
    String a = "i" + i;
    int aa = Integer.parseInt(a);
    ArrayList<String>.add(aa);
}

How could I achieve this? This for loop just adds "i1", "i2" and "i3" to the List, instead of "abc", "bca" and "cba".

Answer 1

Ah, I misunderstood your question at first. Yes, you can do what you want to do trough reflection.

public class Main {
    private String i1 = "abc";
    private String i2 = "bca";
    private String i3 = "cba";

    public static void main(String[] args) {
        new Main();
    }

    public Main(){
        for (int i = 1; i <= 3; i++) {
            String a = "i" + i;
            String f = null;
            try {
                f = (String) this.getClass().getDeclaredField(a).get(this);
            } catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.out.println(f);
        }
    }
}

Output:

abc
bca
cba

Keypoints:

• getDeclaredField() - returns a private field in the given class
• get() - returns the value from a field in the given object

It should be noted though that you should look into using a Map<String, String> structure first. Other answers already provide the explanation for this.

Answer 2

You need to use some of the Map implementations.

For example:

String[] words = { "abc", "bca", "cba" };
Map<String, String> map = new HashMap<String, String>();
for (int i = 1; i <= 3; i++) {
    String a = "i" + i;
    map.put(a, words[i - 1]);
}

At the end, the map looks like:

--key-- | --value--
-------------------
  "i1"  |  "abc"
  "i2"  |  "bca"
  "i3"  |  "cba"

Answer 3

Use Integer.toString() , one of the options is able to use alphabetic characters as well as numerical to represent the String .

You will also need to create a List to add your String s to.

List<String> list = new ArrayList<>();

for (int i = 1; i <= 3; i++) {
    list.add(whatever);
}

Or if you are trying to store a mapping of String to Integer, then you should look at Map , probably HashMap .

Answer 4

Use a String array:

String[] stringArr = new String[3]
ArrayList<String> list = new ArrayList<String>();

stringArr[0] = "abc";
stringArr[1] = "bca";
stringArr[2] = "cba";

for(int i = 0; i<String.length; i++)
{
    list.add(Integer.parseInt(stringArr[i]));
}