How to delimit a string to a string with certain length with Java?

Question

I have a very long String. And I have a function write(String str) that can only support a string with 20 chars. How can I do to cut my long string into strings of 20 chars and loop in my write() function ?

Sorry, what I did :

for(String retval: pic.split("",20)) {
mBluetoothLeService.writeCharacteristic(characteristic, retval)

pic is my long String. however doing this, It's not doing what I want

Thank you in advance !

For example: [Split string to equal length substrings in Java](http://stackoverflow.com/q/3760152) — Tom, Feb 12 '15 at 00:35
possible duplicate of [Split string to equal length substrings in Java](http://stackoverflow.com/questions/3760152/split-string-to-equal-length-substrings-in-java) — Fiddles, Feb 12 '15 at 01:08

score 1 · Answer 1 · answered Feb 12 '15 at 00:40

1

Use the susbtring() method:

with this you can have the 20 first characters:

pic = pic.substring(0, 21)

answered Feb 12 '15 at 00:40

Jorgesys

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The OP states that they want more than 20 chars :P that means you will have to loop – EDToaster Feb 12 '15 at 00:46
"that can only support a string with 20 chars". – Jorgesys Feb 12 '15 at 00:48
He means that `mBluetoothLeService.writeCharacteristic` can only support 20 chars, therefore, and I quote, needs "loop in my write() function" – EDToaster Feb 12 '15 at 00:49

EDToaster · Accepted Answer · 2015-02-12T00:51:49.947

1

Here, using arraylist of Strings, and using substring, supports more than 20 chars

String pic = "THIS IS A VERY LONG STRING MORE THAN 20 CHARS";

ArrayList<String> strings = new ArrayList<String>();
int index = 0;

while (index < pic.length()) {
strings.add(pic.substring(index, Math.min(index + 20,pic.length())));
    index += 20; //split strings, add to arraylist
}

for(String s :strings){
    mBluetoothLeService.writeCharacteristic(characteristic, s); //write the string 
}

or, even better, using regex:

for(String s : pic.split("(?<=\\G.{20})"))
    mBluetoothLeService.writeCharacteristic(characteristic, s);

edited Feb 12 '15 at 00:51

answered Feb 12 '15 at 00:45

EDToaster

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Isn't pic.length() instead of text.length() ? Thanks for this usefull answer tho – Bob Feb 12 '15 at 00:51
I didn't really verified the code but you are sure that this actually makes strings of 20 chars right ? – Bob Feb 12 '15 at 01:00
@Bob Yup, an array of 20length strings, which you iterate through and call the method. – EDToaster Feb 12 '15 at 01:09
Well Actually I got this error : java.util.regex.PatternSyntaxException: Look-behind pattern matches must have a bounded maximum length near index 12: (?<=\G.{20}) , do you know why ? – Bob Feb 12 '15 at 01:18
Yes! it finally worked using the first answer! Regex bugs for me. Anyway thanks for the help ! :) – Bob Feb 12 '15 at 01:34

How to delimit a string to a string with certain length with Java?

2 Answers2