I making fun increase, decrease for item count. I want make count.text plus "T" Character. when I tried to make code like this.
error code: java.lang.NumberFormatException: For input string: "1T"
How can I solve this problem? Any one can help??
fun increaseInteger() {
var count = findViewById<TextView>(R.id.integer_number)
count.text=intent.getStringExtra("case")+"T"
var countResult = parseInt(intent.getStringExtra("case")+"T")
var countValue = countResult+1
if (countValue >= 1 && !decrease.isEnabled) { decrease.isEnabled = true}
intent.putExtra("result",countValue)
display(countValue)
}
fun decreaseInteger() {
var count = findViewById<TextView>(R.id.integer_number)
count.text=intent.getStringExtra("case")+"T"
var countResult = parseInt(intent.getStringExtra("case")+"T")
var countValue = countResult-1
if (countValue <= 1) {decrease.isEnabled = false }
intent.putExtra("result",countValue)
display(countValue)
}
The API is pretty straightforward:
"123".toInt() // returns 123 as Int
"123T".toInt() // throws NumberFormatException
"123".toIntOrNull() // returns 123 Int?
"123T".toIntOrNull() // returns null as Int?
So if you know your input might not be parseable to an Int, you can use toIntOrNull which will return null if the value was not parseable. It allows to use further nullability tools the language offers, e.g.:
input.toIntOrNull() ?: throw IllegalArgumentException("$input is not a valid number")
(This example uses the elvis operator to handle the undesired null response of toIntOrNull, the alternative would involve a try/catch around toInt)
You can use these
val str = "12345"
val str_new = "12345B"
str.toInt() // returns 123 as Int
str_new.toInt() // throws NumberFormatException
str.toIntOrNull() // returns 123 Int?
str_new.toIntOrNull() // returns null as Int?
Related
I am having a String that i would like to convert to Boolean Below is how the string looks like
String isValid = "false";
The String isValid can either be true or false
Is there a way i can directly convert this String isValid to Boolean. I have tried Sample questions and solutions but they are just converting Strings which are hard coded, for example most of the answers are just when the string is true
On top of my head, you can create an extension method for string data-type for your own need with all sorts of requirements checks and custom exceptions to beautify your desired functionalities. Here is an example:
import 'package:test/expect.dart';
void main(List<String> args) {
String isValid = "true";
print(isValid.toBoolean());
}
extension on String {
bool toBoolean() {
print(this);
return (this.toLowerCase() == "true" || this.toLowerCase() == "1")
? true
: (this.toLowerCase() == "false" || this.toLowerCase() == "0"
? false
: throwsUnsupportedError);
}
}
Here, in this example, I've created a variable named isValid in the main() method, which contains a string value. But, look closely at how I've parsed the string value to a bool value using the power with extension declared just a few lines below.
Same way, you can access the newly created string-extension method toBoolean() from anywhere. Keep in mind, if you're not in the same file where the toBoolean() extension is created, don't forget to import the proper reference.
Bonus tips:
You can also access toBoolean() like this,
bool alternateValidation = "true".toBoolean();
Happy coding 😊
This example can work for you, either if is false or true:
String isValid = "true";
bool newBoolValue = isValid.toLowerCase() != "false";
print(newBoolValue);
You can use extensions like this
bool toBoolean() {
String str = this!;
return str != '0' && str != 'false' && str != '';
}
First of All
You should make the string to lowercase to prevent check the string twice
then you can check if the string equal "true" or not and save the result to bool variable as below:
String isValidString = "false"; // the boolean inside string
bool isValid = isValidString.toLowerCase() == 'true'; // check if true after lowercase
print("isValid=$isValid"); // print the result
I opened a PR for this question, I believe that in the future it will be possible to do something native.
void main() {
print(bool.parse("true")); // true
print(bool.parse("false")); //false
print(bool.parse("TRUE")); // FormatException
print(bool.parse("FALSE")); //FormatException
print(bool.parse("True", caseSensitive: false)); // true
print(bool.parse("False", caseSensitive: false)); // false
if(bool.parse("true")){
//code..
}
}
Reference
https://github.com/dart-lang/sdk/pull/51026
I need to retrieve the value from an annotation such as this one that uses a string constant:
#Component(property = Constants.SERVICE_RANKING + ":Integer=10")
public class NyServiceImpl implements MyService {
But I am getting a kind of K_UNKNOWN and the doc says "the value is an expression that would need to be further analyzed to determine its kind". My question then is how do I perform this analysis? I could even manage to accept getting the plain source text value in this case.
The other answer looks basically OK, but let me suggest a way to avoid using the internal class org.eclipse.jdt.internal.core.Annotation and its method findNode():
ISourceRange range = annotation.getSourceRange();
ASTNode annNode = org.eclipse.jdt.core.dom.NodeFinder.perform(cu, range);
From here on you should be safe, using DOM API throughout.
Googling differently I found a way to resolve the expression. Still open to other suggestions if any. For those who might be interested, here is a snippet of code:
if (valueKind == IMemberValuePair.K_UNKNOWN) {
Annotation ann = (Annotation)annotation;
CompilationUnit cu = getAST(ann.getCompilationUnit());
ASTNode annNode = ann.findNode(cu);
NormalAnnotation na = (NormalAnnotation)annNode;
List<?> naValues = na.values();
Optional<?> optMvp = naValues.stream()
.filter(val-> ((MemberValuePair)val).getName().getIdentifier().equals(PROPERTY))
.findAny();
if (optMvp.isPresent()) {
MemberValuePair pair = (MemberValuePair)optMvp.get();
if (pair.getValue() instanceof ArrayInitializer) {
ArrayInitializer ai = (ArrayInitializer)pair.getValue();
for (Object exprObj : ai.expressions()) {
Expression expr = (Expression)exprObj;
String propValue = (String)expr.resolveConstantExpressionValue();
if (propValue.startsWith(Constants.SERVICE_RANKING)) {
return true;
}
}
}
else {
Expression expr = pair.getValue();
String propValue = (String)expr.resolveConstantExpressionValue();
if (propValue.startsWith(Constants.SERVICE_RANKING)) {
return true;
}
}
}
//report error
}
private CompilationUnit getAST(ICompilationUnit compUnit) {
final ASTParser parser = ASTParser.newParser(AST.JLS8);
parser.setKind(ASTParser.K_COMPILATION_UNIT);
parser.setSource(compUnit);
parser.setResolveBindings(true); // we need bindings later on
CompilationUnit unit = (CompilationUnit)parser.createAST(null);
return unit;
}
I am trying to validate a form to make sure the user has entered an integer number and not a string. I can check if the number is an integer as follows:
var possibleNumber = timeRetrieved.text
convertedNumber = possibleNumber.toInt()
// convertedNumber is inferred to be of type "Int?", or "optional Int"
if convertedNumber != nil {
println("It's a number!")
totalTime = convertedNumber!
}
My problem is I want to make sure the user has not entered any text, doubles etc. I only want integer numbers. The following code does not work because it evaluates true if the variable is an integer. What code should I use to evaluate if variable is not an integer?
if convertedNumber != nil {
let alertController = UIAlertController(title: "Validation Error", message: "You must enter an integer number!", preferredStyle: .Alert)
let alertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Destructive, handler: {(alert : UIAlertAction!) in
alertController.dismissViewControllerAnimated(true, completion: nil)
})
alertController.addAction(alertAction)
presentViewController(alertController, animated: true, completion: nil)
Swift 2 changes this: as both Int("abc") and Int("0") return 0, integer conversion can't be used. You could use this:
class Validation {
static func isStringNumerical(string : String) -> Bool {
// Only allow numbers. Look for anything not a number.
let range = string.rangeOfCharacterFromSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet)
return (range == nil)
}
}
It uses a decimalDigitCharacterSet, and can be changed to use whatever character set you want.
func testIsStringNumerical() {
XCTAssertEqual(SignUpLoyaltyViewController.isStringNumerical("123"), true)
XCTAssertEqual(SignUpLoyaltyViewController.isStringNumerical(""), true)
XCTAssertEqual(SignUpLoyaltyViewController.isStringNumerical("12AA"), false)
XCTAssertEqual(SignUpLoyaltyViewController.isStringNumerical("123.4"), false)
}
This is dramatically faster than the Regex answer. (2000 runs, 0.004s vs regex 0.233s)
If the number the user has entered is not an integer, convertedNumber will be nil. Just add an else clause in which you can show the alert.
Int initializer
This works in Swift 2.2 and above. It is based on Minhal Khan's answer which illustrates that Int has an initializer with this signature: init?(_ text: String, radix: Int = default). Since radix has a default value, it can be left out. *more info on this initializer is found here.
var totalTime: Int?
let possibleInt = timeRetrieved.text ?? ""
if let convertedNumber = Int(possibleInt) {
print("'\(possibleInt)' is an Int")
totalTime = convertedNumber
}
else {
print("'\(possibleInt)' is not an Int")
}
print("totalTime: '\(totalTime)'")
Note: I assumed timeRetrieved is a UITextField. The UITextField text property is an optional string (though programmatically not allowed to be nil). Therefore, the compiler requires it be unwrapped. I used the nil coalescing operator (??) to substitute a nil for empty string which does not yield an integer as desired. Here's a post that discusses the optionality of UITextfield.text.
What i had done was get the value and check if it could convert it, works for me
var enteredText = Int(textfield.text)
if enteredText == nil{
//String entered
}
else{
//Int entered
}
Based on #Graham Perks answer a Swift 3 Version as string extension:
extension String
{
var isNumeric: Bool
{
let range = self.rangeOfCharacter(from: CharacterSet.decimalDigits.inverted)
return (range == nil)
}
}
Usage:
"123".isNumeric // true
"abc".isNumeric // false
I really recommend using a REGEX, I was recently trying to validate 10 digit phone numbers using if let _ = Int(stringToTest)... and on 32 bit hardware, I faced range issues.
func validate(value: String) -> Bool {
let PHONE_REGEX = "\\d{10}"
let phoneTest = NSPredicate(format: "SELF MATCHES %#", PHONE_REGEX)
let result = phoneTest.evaluateWithObject(value)
if result == true {
log.info("'\(self.text!)' is a valid number.")
} else {
log.info("'\(self.text!)' is an invalid number.")
}
return result
}
Is it possible to compare two String.Index values in Swift? I'm trying to process a string character by character, and several times I need to check if I am at the end of the string. I've tried just doing
while (currentIndex < string.endIndex) {
//do things...
currentIndex = currentIndex.successor()
}
Which complained about type conversions. Then, I tried defining and overload for < as such:
#infix func <(lhs: String.Index, rhs: String.Index) -> Bool {
var ret = true //what goes here?
return ret
}
Which gets rid of compilation errors, but I have no clue what to do in order to compare lhs and rhs properly. Is this the way I should go about using String.Index, or is there a better way to compare them?
The simplest option is the distance() function:
var string = "Hello World"
var currentIndex = string.startIndex
while (distance(currentIndex, string.endIndex) >= 0) {
println("currentIndex: \(currentIndex)")
currentIndex = currentIndex.successor()
}
Beware distance() has O(N) performance, so avoid it for large strings. However, the entire String class doesn't currently handle large strings anyway — you should probably switch to CFString if performance is critical.
Using an operator overload is a bad idea, but just as a learning exercise this is how you'd do it:
var string = "Hello World"
var currentIndex = string.startIndex
#infix func <(lhs: String.Index, rhs: String.Index) -> Bool {
return distance(lhs, rhs) > 0
}
while (currentIndex < string.endIndex) {
currentIndex = currentIndex.successor()
}
String indexes support = and !=. String indexes are an opaque type, not integers and can not be compared like integers.
Use: if (currentIndex != string.endIndex)
var currentIndex = string.startIndex
while (currentIndex != string.endIndex) {
println("currentIndex: \(currentIndex)")
currentIndex = currentIndex.successor()
}
I believe this REPL/Playground example should illuminate what you (and others) need to know about working with the String.Index concept.
// This will be our working example
let exampleString = "this is a string"
// And here we'll call successor a few times to get an index partway through the example
var someIndexInTheMiddle = exampleString.startIndex
for _ in 1...5 {
someIndexInTheMiddle = someIndexInTheMiddle.successor()
}
// And here we will iterate that string and detect when our current index is relative in one of three different possible ways to the character selected previously
println("\n\nsomeIndexInTheMiddle = \(exampleString[someIndexInTheMiddle])")
for var index: String.Index = exampleString.startIndex; index != exampleString.endIndex; index = index.successor() {
println(" - \(exampleString[index])")
if index != exampleString.startIndex && index.predecessor() == someIndexInTheMiddle {
println("current character comes after someIndexInTheMiddle")
} else if index == someIndexInTheMiddle {
println("current character is the one indicated by someIndexInTheMiddle")
} else if index != exampleString.endIndex && index.successor() == someIndexInTheMiddle {
println("Current character comes before someIndexinTheMiddle")
}
}
Hopefully that provides the necessary information.
Whatever way you decide to iterator over a String, you will immediately want to capture the iteration in a function that can be repeatedly invoked while using a closure applied to each string character. As in:
extension String {
func each (f: (Character) -> Void) {
for var index = self.startIndex;
index < self.endIndex;
index = index.successor() {
f (string[index])
}
}
}
Apple already provides these for C-Strings and will for general strings as soon as they get character access solidified.
I have string value like this:
string strRole = "ab=Admin,ca=system,ou=application,role=branduk|ab=Manager,ca=system,ou=application,role=brankdusa|ab=sale,ca=system,ou=application,role=brandAu";
I just need to retrieve role to string array. I wonder if there is the best way to split the string in C# 4.0
string[] arrStrRole = strRole.Split('|').Select .. ??
Basically, I need brandUK, brandUsa, brandAu to string[] arrStrRole.
Thanks.
string[] arrStrRole = strRole.Split('|').Select(r => r.Split(new []{"role="}, StringSplitOptions.None)[1]).ToArray()
results in an string array with three strings:
branduk
brankdusa
brandAu
you can use string[] arrStrRole = strRole.Split('|',','); and this will split according to | and , characters
You can use String.Split in this LINQ query:
var roles = from token in strRole.Split('|')
from part in token.Split(',')
where part.Split('=')[0] == "role"
select part.Split('=')[1];
Note that this is yet prone to error and requires the data always to have this format. I mention it because you've started with Split('|').Select.... You can also use nested loops.
If you need it as String[] you just need to call ToArray:
String[] result = roles.ToArray();
I would go with Regex rather than splitting string. In combination with your intended Select solution, it could look like this:
var roles = Regex.Matches(strRole, #"role=(\w+)")
.Cast<Match>()
.Select(x => x.Groups[1].Value).ToArray();
You could use an extension like this which would allow you to test it easily.
public static string[] ParseRolesIntoList(this string csvGiven)
{
var list = new List<string>();
if (csvGiven == null) return null;
var csv = csvGiven.Split(',');
foreach (var s in csv)
{
if (string.IsNullOrEmpty(s)) continue;
if(!s.StartsWith("role")) continue;
var upperBound = s.IndexOf("|");
if (upperBound <= 0) upperBound = s.Length;
var role = s.Substring(s.IndexOf("=") + 1,
upperBound - s.IndexOf("=") - 1);
list.Add(role);
}
return list.ToArray();
}
Test below found brankdusa typo in your example. Some of the other answers would not deal with brandAu as it matches slightly differently. Try running this test against them if you like
[Test]
public void Should_parse_into_roles()
{
//GIVEN
const string strRole = "ab=Admin,ca=system,ou=application,role=branduk|ab=Manager,ca=system,ou=application,role=brankdusa|ab=sale,ca=system,ou=application,role=brandAu";
//WHEN
var roles = strRole.ParseRolesIntoList();
//THEN
Assert.That(roles.Length, Is.EqualTo(3));
Assert.That(roles[0], Is.EqualTo("branduk"));
Assert.That(roles[1], Is.EqualTo("brankdusa"));
Assert.That(roles[2], Is.EqualTo("brandAu"));
}
This gives an array of the 3 values.
void Main()
{
string strRole = "ab=Admin,ca=system,ou=application,role=branduk|ab=Manager,ca=system,ou=application,role=brankdusa|ab=sale,ca=system,ou=application,role=brandAu";
var arrStrRole = strRole.Split('|',',')
.Where(a => a.Split('=')[0] == "role")
.Select(b => b.Split('=')[1]);
arrStrRole.Dump();
}