Limiting the number of characters in a string, and chopping off the rest
JavaStringSubstringJava Problem Overview
I need to create a summary table at the end of a log with some values that are obtained inside a class. The table needs to be printed in fixed-width format. I have the code to do this already, but I need to limit Strings, doubles and ints to a fixed-width size that is hard-coded in the code.
So, suppose I want to print a fixed-width table with
int,string,double,string
int,string,double,string
int,string,double,string
int,string,double,string
and the fixed widths are: 4, 5, 6, 6.
If a value exceeds this width, the last characters need to be cut off. So for example:
124891, difference, 22.348, montreal
the strings that need to be printed ought to be:
1248 diffe 22.348 montre
I am thinking I need to do something in the constructor that forces a string not to exceed a certain number of characters. I will probably cast the doubles and ints to a string, so I can enforce the maximum width requirements.
I don't know which method does this or if a string can be instantiated to behave taht way. Using the formatter only helps with the fixed-with formatting for printing the string, but it does not actually chop characters that exceed the maximum length.
Java Solutions
Solution 1 - Java
You can also use String.format("%3.3s", "abcdefgh"). The first digit is the minimum length (the string will be left padded if it's shorter), the second digit is the maxiumum length and the string will be truncated if it's longer. So
System.out.printf("'%3.3s' '%3.3s'", "abcdefgh", "a");
will produce
'abc' ' a'
(you can remove quotes, obviously).
Solution 2 - Java
Use this to cut off the non needed characters:
String.substring(0, maxLength);
Example:
String aString ="123456789";
String cutString = aString.substring(0, 4);
// Output is: "1234"
To ensure you are not getting an IndexOutOfBoundsException when the input string is less than the expected length do the following instead:
int maxLength = (inputString.length() < MAX_CHAR)?inputString.length():MAX_CHAR;
inputString = inputString.substring(0, maxLength);
If you want your integers and doubles to have a certain length then I suggest you use NumberFormat to format your numbers instead of cutting off their string representation.
Solution 3 - Java
For readability, I prefer this:
if (inputString.length() > maxLength) {
inputString = inputString.substring(0, maxLength);
}
over the accepted answer.
int maxLength = (inputString.length() < MAX_CHAR)?inputString.length():MAX_CHAR;
inputString = inputString.substring(0, maxLength);
Solution 4 - Java
You can use the Apache Commons StringUtils.substring(String str, int start, int end) static method, which is also null safe.
Solution 5 - Java
You can achieve this easily using
shortString = longString.substring(0, Math.min(s.length(), MAX_LENGTH));
Solution 6 - Java
If you just want a maximum length, use StringUtils.left! No if or ternary ?: needed.
int maxLength = 5;
StringUtils.left(string, maxLength);
Output:
null -> null
"" -> ""
"a" -> "a"
"abcd1234" -> "abcd1"
Solution 7 - Java
The solution may be java.lang.String.format("%" + maxlength + "s", string).trim(), like this:
int maxlength = 20;
String longString = "Any string you want which length is greather than 'maxlength'";
String shortString = "Anything short";
String resultForLong = java.lang.String.format("%" + maxlength + "s", longString).trim();
String resultForShort = java.lang.String.format("%" + maxlength + "s", shortString).trim();
System.out.println(resultForLong);
System.out.println(resultForShort);
ouput:
Any string you want w
Anything short
Solution 8 - Java
Ideally you should try not to modify the internal data representation for the purpose of creating the table. Whats the problem with String.format()? It will return you new string with required width.