How can I convert the string to Integers and how can I create an ArrayList with these integers?
My String contains only numbers and there is a gap between my numbers.
For example, given the string st1 = "1 2 3 4" or str2 = "11 20 23 24".
I need an ArrayList for str1 like "1, 2, 3, 4"
I tried to use Integer.parseInt(str1) and Integer.valueOf(str1) but these work for such as str1 = "1234"
3 Answers
This method will convert such strings to an ArrayList<Integer>:
public static ArrayList<Integer> toStringList(String string){
String ints[]=string.split(" ");
ArrayList<Integer> list=new ArrayList<>();
for(String str:ints){
list.add(Integer.parseInt(str));
}
}
Remember this method will convert your string such as "1 2 3 4" to a list with 1 to 4 values. If you want to convert it to 1234 you should first remove the spaces:
String str="1 2 3 4 ";
str = str.replaceAll(" ","");
Integer number=Integer.parseInt(str); //equals 1234
3 Comments
Scary Wombat
Better to use
replace as this is not using regex str = str.replace(" ","");
buyufix
Thank you, the first answered my question and it works. How can I do that without using
String ints[]=string.split(" "); , so in a way, without using array?
Omid.N
If you want the numbers to be seperate you have to split the string
You could do so to convert a list of strings to integers. Following @Tim code
String st1 = "1 2 3 4";
String[] array = st1.split("\\s+");
List<Integer> integers = Arrays.stream(array)
.map(Integer::valueOf).collect(Collectors.toList());
System.out.println(integers);
//[1, 2, 3, 4]
Comments
This code will convert any number found within the string to its integer. This will solve your problem.
String str = "1 2 3 4 5 11 12 13 14 15 1 12 123 1234 12345";
int stringLength = str.length();
int[] answer;
String intBuffer = "";
int j = 0, countSpaces = 0;
for (int i = 0; i < stringLength; i++) {
if (str.charAt(i) == ' ') countSpaces++;
}
answer = new int[countSpaces + 1];
for (int i = 0; i < stringLength; i++) {
if (str.charAt(i) != ' ') {
intBuffer = intBuffer + str.charAt(i);
if (i == stringLength - 1)
answer[j] = Integer.parseInt(intBuffer);
} else {
answer[j++] = Integer.parseInt(intBuffer);
intBuffer = "";
}
}
for (int i = 0; i < answer.length; i++)
System.out.println(answer[i] + " ");
st1 = "1 2 3 4"tost1 = "1234"first?