I have a string with this content 12345.
What's the best way to read these individual numbers into an ArrayList of integers? like this:
{1, 2, 3, 4, 5}
Here is what I have so far:
String data = getData();
this.points=new ArrayList<Integer>();
for (int i=0; i<data.length(); i++) {
int pt = Integer.parseInt(data.valueOf(i));
this.points.add(new Integer(pt));
}
The problem is that I get [(0),(1),(2),...] instead of the numbers required.
You need to use the charAt(i) method, valueOf(i) returns you the String value of i and not the i char
This solution should work and keep your memory allocation to a minimum. Note that you need to make sure that only numerical values are present on data.
String data = getData();
this.points = new ArrayList<Integer>(); //if this is a field you should use points.clear() instead.
for (int i=0; i<data.length(); i++) {
this.points.add(Characacter.getNumericValue(data.charAt(i)));
}
Your problem was that you were trying to use the String.valueOf method on the index, which will essentially return the value of i in every iteration
You can use String.charAt to get the corresponding character as char from the position. To add it to the list you need to convert to int.
String data = getData();
this.points=new ArrayList<Integer>();
List<Integer> list = new ArrayList<Integer>();
for (int i = 0; i < data.length(); i++) {
this.points.add(Character.getNumericValue(data.charAt(i)));
}
Character.getNumericValue to return the numeric values.
Integer.parseInt will take the whole number; you want to take it digit-by-digit. For this, use Character.getNumericValue instead.
String data = getData();
this.points=new ArrayList<Integer>();
for (int i=0; i<data.length(); i++) {
int pt = Character.getNumericValue(data.charAt(i));
this.points.add(new Integer(pt));
}
pt followed by a space every time. I got "1 2 3 4 5 ".Use data.charAt() instead of valueOf. So your code should look something like:
String data = getData();
for (int i = 0; i < data.length(); i++) {
int pt = Integer.parseInt(data.valueOf(data.charAt(i)));
this.points.add(new Integer(pt));
}
for (int i = 0; i < points.size(); i++) {
System.out.println(this.points.get(i));
}
Try this
String data = getData();
this.points=new ArrayList<Integer>();
for (int i = 0; i < data.length(); i++) {
this.points.add(Integer.parseInt(s.charAt(i) + ""));
}
You get all the integers like this:
String data = "254980";
List<Integer> list = new ArrayList<Integer>();
for (int i = 0; i < data.length(); i++) {
list.add(new Integer(data.substring(i,i+1)));
}
Test:
for (Integer integer : list) {
System.out.print(integer);
}
prints
2
5
4
9
8
0
substring method inside a loop. Each iteration of the loop requires a full re-scan of the entire string.
String.valueOfdoes - it does not do what you think it does.