check 1 « string « Java Data Type Q&A

1. How to check a String is a numeric type in java

How would you check if a string was a number before parsing it?

2. Easiest Way to Check if a Java String Instance Might Hold Spam Data

I have a process which iterates String instances. Each iteration does few operations on the String instance. At the end the String instance is persisted. Now, I want to add for each iteration ...

4. Checking strings for empty

Very tired this morning so if this is obvious then thats my excuse !!! i am using a buffered reader to read through a csv file - but i dont want to ...

5. How do I check if a string is a valid md5 or sha1 checksum string

I don't want to calculate a file's checksum, just to know if a given string is a valid checksum

6. One step check for null value & emptiness of a string

I have a setter method. Then when another (say generate) method is run, I need to check the value of my fields. So in the case of String property, I need to know ...

7. checking empty string in java

I dont know whats the wroing with the below code.... I am getting input from textbox and putting the input in a string. If the textbox is empty it will return ...

8. Checking if two strings are permutations of each other

How to determine if two strings are permutations of each other

9. Check how much a String sounds like another one in Java

I'd like to know if there is any class in Java able to check, using its own criteria, how much a String is equal to another one. Example :

  • William Shakespeare / ...

10. How to check a string against null in java?

How can I check a string against null in java? I am using

but it's not working.

11. How to check that Java String is not all whitespaces

I want to check that Java String/character array is not just made up of whitespaces. How would I go about doing this in Java. This is a very similar question except it's ...

12. I'm trying to make a void to check if something is true, and if something is, make a string say something depending on what was true

     public void sortingFamilyName(Player player) {
  if (player.Zamorak == true) {
   godFamily = "Zamorak";
  if (player.Saradomin == true) {

13. In Java, is it possible to check if a String is only ASCII?

Character.isLetter(c) returns true if the character is a letter. But is there a way to quickly find if a String only contains the base characters of ASCII?

14. check for vowel in a given string

I would like to write a program which checks whether or not the input character is a vowel, but I'm not able to input a character with jTextField1. I tried Character.parseChar ...

15. How do you check whether every word in one string is found in another string?

Let's say I have a book title and I search for it in a database. The database produces matches, some of which are full matches and some of which are partial ...

16. Checking containment in a Set of strings in Java

I have a Set of String[]. I want to check whether this Set contains another String[].

Set<String[]> s  = new HashSet<String[]>();
s.add(new String[] {"lucy", "simon"});
System.out.println(s.contains(new String[] {"lucy", "simon"}));
However, false is ...

17. Java : Parsing a String & Checking for "@"

How can i use Pattern.compile to check whether a string contains "@". Something like this->>

    Pattern pattern = Pattern.compile("^[\\w\\.-]*@[\\.\\w-]*$");
    Matcher matcher = pattern.matcher(string);

18. Check that word all words from one string exist in the other

How can I check that all the words from string #2 exist in String #1? It should be case insensitive and I want exclude all punctuation and special characters during comparison ...

19. Java need help checking if string is instance

I have an interface, GenericExpression, that gets extended to create expressions (ie AndExpression, OrExpression etc.). Each GenericExpression implementation has a string that represents it (ie "&", "+", etc.) (stored as a static ...

20. In java, how can I check the content of the last line in a string made up of many lines?

I'm reading a text file made up of many lines line by line and converting it into a string.
I'm trying to figure out how to check if the last line of ...

21. how to check a string is not null


how to check the string is not null


22. What's the better way to check if a String is empty than using String.trim().length() in Java 5/6?

There probably is a method to return the index of the first non-blank char in a String in Java5/6. But I cannot find it any more. A code anylizing tool says ...

23. How do I check for nulls and empty string for a needle in a haystack?

Situation: I am coming across a lot of checks in my code. And I would like to know of a way in which I can reduce them.

if(needle!=null && ...

24. Check if a String is valid UTF-8 encoded in Java

How can i check if a string is in valid UTF-8 format?

25. Checking if a newly submitted string is a valid word

I have a string , after changing the positions of letters in the string I will be getting new strings, Here I have to use dictionary and check whether the newly ...

26. How to check how many letters are in a string in java?

A) How do you check how many letters are in a Java string? B) How do you check what letter is in a certain postition in the string (i.e, the second letter ...

27. Do I need to check null on both sides of an OR condition?

Consider member variable:

String foo;
I only want to call setFoo if foo has not previously been set or currently is empty. For this purpose, I am not sure if this is sufficient:
if(foo==null || ...

28. Apache's StringUtils.isBlank(str) vs. Guava's Strings.isNullOrEmpty(str): Should you routinely check for whitespace?

Is there any advantage in using

from Apache commons-lang. vs
Strings.isNullOrEmpty(String string)
from Google Guava? I want to replace hundreds of cases of they following usage in a Java project:
if(str == null || ...

29. "Null variable checking" in String

Generally, is there a difference between

in that the first will not cause a null pointer exception, but the second one will if in both scenarios myStrVar is null?

30. String null check

I have tried this for 2 hours , but I've given up. I am checking the value of a String this way:

    value = "Anynomous"
But still the string ...

32. I am looking java code to check String is Valid XHTML or not


<h2>Legal HTML Entity References</h2><table align="center" border="0" cellspacing="0" cellpadding="2">
<tr><th align="left" width="145" valign="top" height="40">hi this is header</th></tr><tr><td>hello<td></tr></table>

33. How to parse strings safely?

We know that using string concatenation to form SQL queries renders a program vulnerable to SQL injection. I usually get around that by using parameter features provided by the API of ...

34. check the value of a word inside a string

I have a string like

String example =  "Tag: something Id: somethingElse Score: 0.8";
How can i check if Score is higher/equal/lower than 0.

35. How to check whether the string is in encoded form or not

I have a method inside that i am encode the input string,and then i check the value with the my data base value(stored in the encoded form),

public void checkString(String strPass){
String s ...

36. check for null charecter in a string

i want to know can we use array index value for string operation? No, you cannot. A string is a string and has string methods etc, an array is an array ...

37. Checking string

Hi I retrieve data(String values of X column) from Database. Data in database will be any of the three a. "NULL" b. some value c. nothing(blank) note: blank refers to empty not blank space I need to set values based on the data(String) received like If the value is not null if(data!=null or when data is empty) x="y"; I am facing ...

38. how to check for specific string pattern(using jdk 131)

You could also copy the string to a string buffer and delete all the non-alpha characters then check for POBox using indexOf. Without regex, there's no simple way to do it. Another possibility is to construct an array of strings with each element containing one possible permutation of "PO Box", then use indexOf from either String or StringBuffer to see if ...

39. Check Code for HardCoded Strings

40. Check For Strings

41. Check for String

Hi Bhuvana, This sounds like maybe a programming assignment, so i will give you a couple ideas but won't give you the code. You are on the right track using substring. if you know that a comma is at position p in String s, then you can use s.substring(p+1) to give you the part of the String that is to the ...

42. Should be easy... checking for null in String error

Thanks for the responses. I do acutally like the try/catch solution the best, since I just found out the problem is actually that the value null is "null". Somewhere someone is initializing the value to the string "null". Nobody knows why. So the value isn't null afterall which falls right into your response. There is some nervousness about implementing something like ...

43. Check String for null without error?

Hello All, Ok i need to ask a stupid question. How would you go about checking a string for null without getting an exception. The error is caused by this type of check. ----------------------Error Code------------------------- String ABC = req.GetParameter("FieldABC"); if (ABC.equals(null)) { ABC = "Empty Field"; } ----------------------End----------------------- Now it could be done like this but its ugly. ---------------------Ugly Code------------------ String ...

44. How to check if String() value is numeric

Hello, I have a situation where I want to validate whether the value passed in as a String() is a numeric v. alpha/special char value. The process that will consume this data post-validation will be expecting numeric values. Can someone give me a hint with how to do this without using a NumberFormatException? If the Exception is encountered the only recovery ...

45. checking if String is numeric

46. how to check whether a string is null or not

hello CR, thanks for the notification. yes.. if the requirement is to deal with only a NON-EMPTY string (blankspaces not to be considered), trim() can be used before finding its length. trim() is used to get the string by omitting the whitespaces at both the ends [ April 16, 2007: Message edited by: Raghavan Muthu ]

47. Checking the value of a string

I am trying to complete exercise 5-4 of the SCJP study guide and have hit a problem when trying to check the value of the first parameter supplied on the command line when running the program. I have coded the class thus: class MyException { static String checkFood(String instring) throws BadFoodException { if (instring == "Good") { System.out.println("The food is good"); ...

48. Check for null string

49. Checking for empty(?) string

You should almost never do string comparisons with the == or != operators. Use the String.equals() method instead. This is discussed often here so you should be able to find a more detailed explanation with the search tool. This is also covered at the beginning of almost every book on Java that I've ever seen.

51. Checking a string

[Pull Rank] Please, Ravi, and James, don't be annoyed with me. We're all here to learn, so when responding to others, please focus on helping them discover their own solutions, instead of simply providing answers. That is what it says on the entry page to the beginner's forum. It is much better to give a hint, which Maja Grajewska will find, ...

52. check for NOT AND OR in a string

54. How to check for a particular word in a string.

I have to do validation for a string passed in a particular field in a jsp.The string that is passed must not contain words like "script","delete","insert" etc.If these words are somehow found in the string then I will redirect the current page to an error page.Now I will have to use a java class file which will compare the strings passed ...

55. Check if a String has alphabets

56. check string inside string

i know i could prolly do a variation of string.indexof whereby i check to see if 1 is in there and 2 is in there and 3 and then return a true, but is there another way? just checking to see if there is a more pro way of doing it tbh

57. Check if string is numbe

Hi, Do you get the answer already? Or you can try in such way : public static boolean isFamName(String b){ if(b.length()==0||b==null){ System.out.println("Please enter your family name correctly?"); return false; }else{ return true; }//close if-else statement }//close isFamName And since when user input String b is empty, then you will println to user to key in family name correctly and also return ...

59. Checking The Contents of a String

Actually there is a space between the numerics and the characters. Maybe it just seems lazy but I want to get the number as a whole. Simply put If its "300 dogs" i want to make a calculation based on the fact that they are dogs. The checking if they are dogs is not a problem, its the number before the ...

60. Checking a string var to an actually string?

So, I made a random number generator/guessing game just for fun and practice. But I'm stuck.. at the end of the program if you guessed wrong it asks you if you want to try again. I have a string var and I'm trying to check if it is equal to the word "Yes", and if it is then run the program ...

61. checking length of string from command line arguments

)); 5. } 6.} When I compile, I get an error message on line 4: The method length(String) is undefined for the type weekdays. From what I understand, args is an array of strings taken from command line arguments. So I believe, that I am asking for the length of the string, when I say: length(args). Also, the length() method is ...

62. String valid check

63. how to check if the element of the list references a string

Thanks Im not sure if this is what I was looking for. I just want to check if an element of my list is of a type String or not. I have created something like this but it returns an error "unexpected type" any idea why?: public boolean hasName() { for (Employee employeeLis:employeeList) { if(employeeLis.getFirstName().getClass().getName()="[Ljava.lang.String"); {return true;

65. Check if string has changed?

66. check if string is unique

Hi all, What i need to do is check if a value entered is unique i.e. that it hasn't been entered before. I have a buffered reader to get the input, which is then stored as a string. I just need to manipulate this string. If someone could tell me what to add to my code to add this functionality it ...

68. checking string for digits

69. Checking string value

71. String check

72. To check the sub string

73. Checking a string value/type.

Is there a way of checking that a string is a certain type. example... I have argstrings a i want to make sure only numbers are outputted. I know how to convert the string to an int. value, but im not sure how to check if the string is actually something else (such as "abc"). cheers in advance

74. set string to be null and then check it

JavaMessi wrote: you get the key point already, that should more than enough. The hell I do. What line causes the NullPointerException to be thrown? What is the actual question? As you probably know, programming is an exercise in precision for if you're not precise with the grammar, spelling and capitalization of the code you attempt to compile, you will not ...

75. Checking end of a String

I have a relatively simple question, but I've been looking since yesterday and can't find the answer to my question. I'm writing a program that reads a sentence using a dialog box. Depending on the last character of the sentence, output another dialog box identifying the sentence as declarative ( ends with a period ), interrogative ( ends with a question ...

76. How to check if entered String is not a double/int?

So, in a calculator program, how to check that the input string consists of just numbers? Because when trying to parse into a double non numbers crashes the program... id like it to loop back to asking the number again. I was trying to do a check via a while and a for loop with no luck =/

77. Checking for empty strings

78. java - how to check if a string is null

79. "Properly" checking if a string is only digits

Hi, Whats the best way to check a string if it contains any digits only? Right now I am doing the below code snippet which works if the user types in whole digits. But it obviously fails to give me the correct boolean when someone types decimals. I could always do a replace all of the decimal but wanted to know ...

80. String Language Checking

Hi, what is the best way to check that a certain string matchs a certain language, for example i have user input name (String) where i need to validate that its Arabic, is it recommended to use the uni-code ranges checking, or is there a better way of doing so. Thanks in advance

81. How to check for double quote in a string?

Hi All, I am working on a bug and while analyzing it found that if the String does not have double quotes,then the logic fails.So can someone please tell me is there an efficient way of checking to see if the String contains double quotes at the beginning and at the end? If the double quotes does not exist,I should be ...

82. Check if string follows a pattern.

83. String fomart check

Hi, I have to process a string for a specific format. Basically, need to check if it confirms to the given format. The string I usually get is a numeric string. However might get some invalid values. Format: "DDD.D" , where D is any digit from [0-9] Input is String Output: boolean "100.1" ---> true <----- "1.123" ---->false "-23" ----->false "java2" ...

85. Check for NOT, AND and OR in a string

if more > 2 of them are present, then throw an error message. If any of them are at the beginning/end of a string, then throw an error message. As per the spec, they should be only in the middle of a string.Eg: jp OR chase OR morgan AND jp OR morgan AND trust - not permitted.

86. Checking for nulls -> creating a string -> can't access the string value!

Thanks for reading this. I have a small project where I need to read an XML file that is created by another application. Sometimes some of the XML fields are blank. To prevent errors, I check to see if the specific XML field has a value or not. If there is no value (in this case value6), I set the String ...

87. How to delay or wait before checking a String's length?

Hi everyone, new to the forums and first time post here. Please excuse me if I haven't picked the right place to post this. I am writing a small simple program to read a scanned barcode number (it is emulated as keyboard, so no need to get fancy here). So far I have my program using a "Key Released" event to ...

89. Checking Content Of A String ?

90. Checking a String value

It sounds like you need a isEatable(String input) method. In that method you can check if the input passed in is eatable or not. In your case you could store a list of eatable items somewhere and check if the current item is eatable or not. If you wantalso say thigns like "everything that has cookie in ti is eatbale" you'll ...

91. How to check string...

Hello all! Im writing a scrabble program and i need to filter results So far ive filtered it down to if it contains 1 of my characters on my rack. Now i need to filter it again, if it contains 2(or more) characters.(i can get rid of my first filter if i figure this one out :P) Im just wondering how ...

93. Check if a String is in UTF8

I understand all of that. The only difference I see is that you consider the physical representation and I consider the logical representation. It makes little or no difference to the answer to the OP's question whether one considers the physical or logical view. The answer is still that UTF-8 does not come into the definition of Java Strings.

94. How to check if string is valid?

you could always parse it with the Integer class within a try/catch block, and if it passes parsing, it's valid, otherwise it's not. Also, your delimiter looks more like a comma (,) than a period (.). I'd recommend sticking with a comma since it's a more common delimiter. I'd then use String.split(",") to get an array of String, trim them, check ...

96. In Java, is it possible to check string startsWith with a List?

Hi All, for example i am having a string called "ONE". I'm having a list which has "ONE", "TWO", "THREE", "FOUR" etc., Now i want to check whether "ONE" is startsWith any one the string specified in the java.util.List. In my case, it has to return true if "ONE" is given. if i give "NINE" it has to return false. How ...

97. Checking a range of strings

Thanks, but is there any other way without parsing the String, What if I have 2 strings without numbers such as Apple and Pear and want to see if banana falls ins that range, which in my case would since it is going by alphabetical. Is there a number representation you can get from a string?

98. String Checking

Hi, i have a problem with password checking. my password do have some constraints. first, it can contain lower character, but this is not a must. But, when the password contains lower characters, it is limited to [abcde]. second, it must contain a number, with minimum occurence one. the number have to be [1-9]. examples : "abc" invalid (doesnt contains number) ...

99. Ways to check a string for null.

100. How to check return NULL with String

catch { // print(error message); whatever } If you're going to catch an exception, you should actually handle it. Just catching and logging lets the program go on as if nothing were wrong. Don't bother catching it if you're not going to do somethign about it. Now that you've caught it, your method is still going to complete normally, so you ...