CODEWITHSUNDEEP
javaarrays
Allen Tran
Allen Tran

Reputation: 49

How to Convert an String array to an Int array?

I have made research for a couple hours trying to figure out how to convert a String array to a Int array but no luck.

I am making a program where you can encrypt a message by using three rotors. I am able to type a message and get the index number for the first rotor (inner rotor) to encrypt into the third rotor (outer rotor). The problem is the index number is in a string array which I want it to become a int array.

Yes, I have tried

int[] array == Arrays.asList(strings).stream()
        .mapToInt(Integer::parseInt).toArray();

or any form of that. I'm not unsure if I have java 8 since it doesn't work, but it gives me an error.

Can someone help me how to convert a String array to a Int array?

public void outerRotorEncrypt() {
    String[] indexNumberSpilt = indexNumber.split(" ");

    System.out.println("indexNumber length: " + indexNumber.length()); //test
    System.out.println("indexNumberSpilt length: " + indexNumberSpilt.length); //test
    System.out.println("Index Number Spilt: " + indexNumberSpilt[3]); //test
    System.out.println("");

    System.out.println("");
    System.out.println("testing from outerRotorEncrypt");
    System.out.println("");

    for(int i = 1; i < indexNumberSpilt.length; i++){
        secretMessage = secretMessage + defaultOuterRotorCharacterArray[indexNumberSpilt[i]];
    }
    System.out.println("Secret Message from outerRotorEncrypt: " + secretMessage);
}

Upvotes: 3

Views: 1698

Answers (6)

flavio.donze
flavio.donze

Reputation: 8090

int[]

If you want an int[] array:

String indexNumber = "1 2 3 4";
String[] indexNumberSpilt = indexNumber.split(" ");
int[] result = Stream.of(indexNumberSpilt).mapToInt(Integer::parseInt).toArray();
System.out.println(Arrays.toString(result));

Integer[]

String indexNumber = "1 2 3 4";
String[] indexNumberSpilt = indexNumber.split(" ");
Integer[] result = Stream.of(indexNumberSpilt).mapToInt(Integer::parseInt).boxed().toArray(Integer[]::new);
System.out.println(Arrays.toString(result));

Both examples will print:

[1, 2, 3, 4]

Upvotes: 0

Rahul Singh
Rahul Singh

Reputation: 19622

Small Demo 

String[] string = { "0", "1", "11", "0", "0", "1", "11", "0", "0", "1",
            "11", "0" };
    List<String> temp = Arrays.asList(string);
    List<Integer> temp1 = new ArrayList<Integer>();
    for (String s : temp) {
        temp1.add(Integer.parseInt(s));
    }

    int[] ret = new int[temp1.size()];
    for (int i = 0; i < ret.length; i++) {
        ret[i] = temp1.get(i).intValue();
    }

    System.out.println(Arrays.toString(ret));
}

Upvotes: 0

Darshan Mehta
Darshan Mehta

Reputation: 30809

int[] array == Arrays.asList(strings).stream()
        .mapToInt(Integer::parseInt).toArray();

The reason why it's giving an error is because of ==, changing that to = (assignment operator) should work, e.g.:

String[] input = new String[]{"1", "2"};
int[] array = Arrays.asList(input).stream()
        .mapToInt(Integer::parseInt).toArray();
for(int a : array){
    System.out.println(a);
}

Upvotes: 1

Darshit
Darshit

Reputation: 361

If you are using Java8 than this is simple way to solve this issue.

List<?> list = Arrays.asList(indexNumber.split(" "));
list = list.stream().mapToInt(n -> Integer.parseInt((String) n)).boxed().collect(Collectors.toList());

In first Line you are taking a generic List Object and convert your array into list and than using stream api same list will be filled with equivalent Integer value.

Upvotes: 2

Mariano L
Mariano L

Reputation: 1879

Have you tried:

int[] array = new int[indexNumberSpilt.lenght()];
for ( int i=0;i<indexNumberSpilt.lenght();i++ ){
   array[i] = Integer.valueOf(indexNumberSpilt[i]);
}

Upvotes: 1

Lauyou.com
Lauyou.com

Reputation: 19

static int[] parseIntArray(String[] arr) {
    return Stream.of(arr).mapToInt(Integer::parseInt).toArray();
}

So take a Stream of the String[]. Use mapToInt to call Integer.parseInt for each element and convert to an int. Then simply call toArray on the resultant IntStream to return the array.

Upvotes: 1

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