Kabla ya kuendelea na somo, kwanza tengeneza faili kwa kutumia note pad, hilo faili liite dart.txt zingatia wakati wa ku save chaguwa seve as type, weka all files kisha ndipo utaweka hilo jina dart.txt kisha hilo faili liweke kwenye folder lenye project yako ya Dart.
Hilo faili ndio tunakwenda kulifanyia kazi katika somo hili. Tutakwenda kujifunza kupata taarifa za faili, kulisoma na kuandika data. Pia tutakwend akujifunz akutengeneza faili lingine.
Ndani ya hilo faili lako weka maneneo haya
Karib bongoclass
Haya ni mafunzo ya dart programming
Jinsi ya kusoma faili:
Sasa ili tuweze kusoma faililetu tutatumia method hii readAsSteingSync() ila kabla ya hapo tutatakiwa kutengeneza file object kwa kutumia function File() ndani yake tutaweka jina la faili. Pia kama faili lipo kwenye directory ama folda lingine utaweka link yake hapo ndani ya hiyo function. Jambo la kuzingatia zaidi ni ku import io library.
Mfano
import 'dart:io';
void main() {
// tengeneza file object
File file = File('dart.txt');
// soma file
String contents = file.readAsStringSync();
// print file
print(contents);
}
Pia unaweza kusoma faili kw akutumia split()
import 'dart:io';
void main() {
// open file
File file = File('dart.txt');
// read file
String contents = file.readAsStringSync();
// split file using new line
List<String> lines = contents.split(' ');
// print file
print('---------------------');
for (var line in lines) {
print(line);
}
}
Angalia picha hapo chini
Pia kwa kutumia substring() unaweza kusoma kijisehemu tu cha faili mfano tunataka kusoma kuanzia character ya 0 hadi ya 11
import 'dart:io';
void main() {
// open file
File file = new File('dart.txt');
// read only first 10 characters
String contents = file.readAsStringSync().substring(0, 11);
// print file
print(contents);
}
Kupata taarifa za faili
Hapa utajifunz ajinsi ya kupata taarifa muhimu za faili kama:
- Ukubwa wa faili hapa tutatumia length
- Location hapa tutatumia path
- Muda lilipopata update hapa tutatumia lastModifiedSync
- Mara ya mwisho kutumika hapa tutatumia lastAccessedSync
- Idadi ya mistari hapa tutatumia readAsLinesSync().lenth
import 'dart:io';
void main() {
// open file
File file = File('dart.txt');
// get file location
print('File path: ${file.path}');
// get absolute path
print('File absolute path: ${file.absolute.path}');
// get file size
print('File size: ${file.lengthSync()} bytes');
// get last modified time
print('Last modified: ${file.lastModifiedSync()}');
//last access
print('File last accessed: ${file.lastAccessedSync()}');
print('Number of lines: ${file.readAsLinesSync().length}');
}
Unaweza kuongeza taarifa zaidi na zaidi. Tembelea website yao ya Dart ili kupata taarifa zaidi kuhusu mafaili.
Mwisho
Katika somo linalofuata utakwend akujifunza jinsi ya kuandika data kwenye faili kw akutumia dart.
