How to check the datatype of entered value in TextField? I have found other questions related to this query at Stack Overflow, but those are related to other languages, as: C#, Swift etc.
I don't want to parse the value of String to integer, or vise versa. I want to identify the Datatype of the value which is contained by jTextField1.
Usually in java, jTextField1.getText(); returns the String value in Java.
What I want is:
if jTextField1 contains Hello World then answer should be String
if jTextField1 contains 123 then answer should be integer
if jTextField1 contains 354.55 then answer should be Double
Is there any way to do this?
General - the datatype of a field is always String....
Integer.parse or Double.parse would be the most useful tools here, but if you dont want to use it, you can check each character individually if its a number Character.isDigit.
If any is not: String
If all are and no separator --> int
else --> double
but as said - I would use the existing api methods - because at the end, parsing is parsing
Related
This question already has answers here:
Java BigDecimal can have comma instead dot?
(3 answers)
Closed 3 months ago.
I have a method to set a BigDecimal number that is given as String:
private Client mapClient(Client client){
ClientRequest clientRequest = new ClientRequest();
// Code
clientRequest.setCashAmount(castStringToBigDecimal(client.getCashAmount()));
// More Code
}
My castStringToBigDecimal method is the follosing:
public BigDecimal castStringToBigDecimal(String value){
BigDecimal response = null;
if(value != null && !value.equals("")){
value = value.replaceAll("[.]", ",");
response = new BigDecimal(value);
}
return response;
}
An example of the input value is "1554.21"
I need that the bigDecimal separator to be a comma, not a dot. But this is giving me an exception.
EDIT
The value is the following:
And the exception is:
java.lang.NumberFormatException: Character , is neither a decimal digit number, decimal point, nor "e" notation exponential mark.
BigDecimal doesn't represent a rendering. In other words, whether to use a comma or a dot as separator is not part of the properties a BigDecimal object has.
Hence, you do not want to call .replaceAll. (And separately, you'd want .replace(".", ",") - replace replaces all, and replaceAll also replaces all and interprets the first arg as a regex, and is therefore needlessly confusing here). Just pass it with the dot.
To render a BigDecimal, don't just sysout it, that will always show a dot and there is nothing you can do about that. toString() is almost never the appropriate tool for the job of rendering data to a user - it's a debugging aid, nothing more. Use e.g. String.format("%f"), specifying the appropriate locale. Or use NumberFormat. The javadoc of BigDecimal explicitly spells this out.
There are various other issues with your code:
"cast" is the technical name for the syntactic construct: (Type) expr; - and this construct does 3 utterly different things, hence using it to describe a task, i.e. use it in a method name, is a very bad idea. In particular, only one of the 3 things it does converts anything, and you clearly use it here in the 'convert something' meaning. This is misleading; only if it's all primitives does the cast operator convert, and BigDecimal isn't primitive. Call it convertTo or whatever you please, not "cast".
BigDecimal is an extremely complicated tool for the job and usually not the right tool if you want to represent financial data. Instead, represent the atomary unit in a long and call the appropriate rendering method whenever you need to show it to a user. For example, for euros, the atomary unit is the eurocent. If something costs €1,50, you'd store "150", in a long. Before you think: But, wait, I want to divide, and then I'd lose half a cent! - yes, well, you can't exactly send your bank a request to transfer half a cent, either. Also, try to divide 4 cents by 3 with a BigDecimal and see what happens. Dividing financial amounts is tricky no matter what you use, BD isn't a catch-all solution to this problem.
I looked up the source code for Java 8's implementation of BigDecimal (https://github.com/frohoff/jdk8u-dev-jdk/blob/master/src/share/classes/java/math/BigDecimal.java), and the period character is hard-coded in that source as the decimal point. I would not have thought this of a language for which internationalization has been so thoroughly designed in, but there it is, line 466.
Given that the author(s) of BigDecimal failed to take locale into account in such a basic way -- the use of comma instead of period as the decimal separator in Europe is well-known -- I'd have to say you cannot use that BigDecimal constructor on unaltered Strings that are otherwise formatted correctly but which (might) have a comma separator. There are other options -- the previous SO post referred to in one of the comments has one -- but it appears you cannot convert your String this way.
(One minor point -- you are not "casting" anything. That word has a specific meaning in OO programming, and a more specific one in Java, and has very little to do with your question. It is incorrect to refer to conversion as casting.)
I am new to Java and using the JIRA MISC Custom Fields add-on and require some logic assistance to solve math functions between two drop down fields.
Field one is "User Cost"
This field contains four string selections with the user price posted at the end of the string.
sam costs .21
mitch costs .419
Lance costs 2.66
xmen costs 13.338
Field two is "Usage"
This field contains two string selections:
24 hours (unless maintenance)
12 Hours (7a-7p)
The argument should be invoked into a new field called "Total User Cost." This field would automatically display the correct price for user and usage amount.
The equation blueprint would be as follows:
Cost*31(calendar days)*usage(12 || 24)
I would want my form to update based on user input selection of these two fields and other variables in my equation.
This is what I have so far:
[
Thank you in advance for any feedback!
If I understand correctly, you first need to initialize issue to something. (It looks red in your images like that variable doesn't exist)
Then, you can do something like this
double costSam = 0.21;
String userSam = issue.get("customfield_10620");
Then, if you are needing to convert or otherwise do some math on userSam, then you need this
double samTotal = costSam * Double.parseDouble(userSam);
Some flaws with your code
You have to define types for your values like String or double.
If you have String x = "hello" on one line, then x = 0.4 on the next, that won't work because of incompatible types
If you did have compatible types on consecutive lines, then the first line is pointless unless using the value from the first, as the second line overwrites the value of the first one
I'm a beginner in Java, and NetBeans. I'm trying to make a simple program where you introduce 2 numbers and their sum gets divided by two. However, I'm using JFormattedTExtFields and I don't know how to customize the allowed input in them. Basically I'm trying to find out how to:
Only allow numbers to be entered in JFormmatedTextField;
Only allow a certain amount of numbers;
You could use a NumberFormat and specify the maximum number of integer digits with setMaximumIntegerDigits.
Here's a nice article.
Basically you can do something like:
NumberFormat f = NumberFormat.getNumberInstance();
f.setMaximumIntegerDigits(maxDigitsAmount);
JFormattedTextField field = new JFormattedTextField(f);
The Format should guarantee that the inserted String satisfy the format. Anyway even if a number is supplied, the textfield will store it as a String. So if you need your original Integer you need to rebuild it like suggested #noise:
Integer i = Integer.toString(field.getText());
I am aware of the various posts floating out there with regards to the same issue.
Mine its a little bit different and it might be a little obvious, but I will need your comments.
I am currently using Hibernate Search and Lucene to Index entity properties.
I have a bunch of Double properties on my entities.
These entities using the default Bridges from Lucene (Bridge i.e the one in charge converting LongToString and StringToLong) are giving me troubles once the scientific notation starts to be used.
I am trying to show on DataTables on a .xhtml Credit and Debit amounts, their lenght can be as long as 18 digits, and their DataBase (DB2) type is BIGINT.
I can not change the DataBase type
to Long for example.
I can not change either the Double
type attributes of my entities
either to for example Long
So whats the question?
Is there a way from a String say "1234567890" to retrieve a Double whose format is 1234567890 and not 1.23456789E9 as it is being done by default by Double.parseDouble(FormattedString)?
PD: I am aware of the existance of DecimalFormat, however take into account using this formater will give me a String formated correctly say : "#######.E0" but what I really need is a Double with such format, however when doing Double.parseDouble(FormattedString) I will loose such format.
Hope I was clear and thanks for any help.
Is there a way from a String say "1234567890" to retrieve a Double whose value is 1234567890 and not 1.23456789E9 as it is being done by default by Double.parseDouble(FormattedString)?
Your question doesn't really make sense. 1234567890 is the same value as 1.23456789E9 and a double represents one of them, if and only if it also represents the other.
I am aware of the existance of DecimalFormat, however take into account using this formater will give me a String formated correctly say : "#######.E0" but what I really need is a Double with such format, however when doing Double.parseDouble(FormatedString) I will loose such format.
No, there is no way to construct a Double so that it is displayed in a certain way. The toString method for Double is what it is, and it can't be changed.
The only thing you can do is to for instance use DecimalFormat or String.format but as you've noted, you'll always end up with a String.
Don't know nothing of Lucene, but you can never have a Double in a .xhtml Document it is always a characterstring. A Double doesn't have a Format, only a String representation of a Double has.
So I finally got the solution to my problem.
After rounding up what aioobe and Jens Schauder said. I am able to format the text dynamically on my .xhtml with the following tag:
<h:outputText value="#{recordTable[column.property]}"
rendered="#{column.header ne 'Details' and
column.header eq ('Total Credit Amount' or
'Total Debit Amount')}">
<f:convertNumber pattern="########"/>
</h:outputText>
Thanks for making clear to me these basic stuff I had blurred :)
I've been reading up on the net about the issues with handling float and double types in java. Unfortunately, the image is still not clear. Hence, i'm asking here direct. :(
My MySQL table has various DECIMAL(m,d) columns. The m may range from 5 to 30. d stays a constant at 2.
Question 1.
What equivalent data-type should i be using in Java to work (i.e store, retrieve, and process) with the size of the values in my table? (I've settled with double - hence this post).
Question 2.
While trying to parse a double from a string, i'm getting errors
Double dpu = new Double(dpuField.getText());
for example -
"1" -> java.lang.NumberFormatException: empty String
"10" -> 1.0
"101" -> 10.0
"101." -> 101.0
"101.1" -> 101.0
"101.19" -> 101.1
What am i doing wrong? What is the correct way to convert a string to a double value?
And what measures should i take to perform operations on such values?
EDIT
This is the code -
System.out.println(dpuField.getText());
Double dpu = new Double(dpuField.getText());
System.out.println(dpu);
Yes, the problem lies with getText() reporting the wrong value of the dpuField.
This method is called on the JTextField keyTyped event. So what's going wrong here?
EDIT 2
Looking at :
http://journals.ecs.soton.ac.uk/java/tutorial/post1.0/ui/keylistener.html
Apparently, keyTyped() does not give me the keycode. I'll have to switch to keyRealeased()
What equivalent data-type should i be using in Java to work (i.e store, retrieve, and process) with the size of the values in my table? (I've settled with double - hence this post).
Since it's a DECIMAL field, you should prefer java.math.BigDecimal. You can store it in DB using PreparedStatement#setBigDecimal() and you can retrieve it from DB using ResultSet#getBigDecimal().
While trying to parse a double from a string, i'm getting errors
This can't be true. The problem lies somewhere else. Maybe it is just not returning the data you expect to be returned or you are not using/debugging the values you expect them to be.
if you need exact precision without rounding errors, you should use a BigDecimal.
Your code looks OK - could it be that dpuField.getText() somehow cuts the last character from the string values you list above?
Update: you say
Yes, the problem lies with getText() reporting the wrong value of the dpuField. This method is called on the JTextField keyTyped event.
Could it be that getText() returns the value of the field before the last typed key is actually appended to it?
For decimal, I believe you risk losing precision if you don't use a BigDecimal on the Java side, as some decimal fractions can't be stored as a binary fraction.
Prefer Double.valueOf(String) over the constructor, but that's a valid way. Something else must be going on (i.e. I doubt those are the actual String values you're passing in).
Question1: It's bad idea to map DECIMAL columns to Double, usually the BigDecimal is the correct type. http://java.sun.com/j2se/1.3/docs/guide/jdbc/getstart/mapping.html#1055175
Question 2: You are doing something wrong; print the String value before converting.