Limiting the number of characters in a string and chopping off the rest

Question

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

User · Accepted Answer

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.

User · Answer

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

User · Answer

You can achieve this easily using       shortString   longString substring 0  Math min s length    MAX LENGTH

User · Answer

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

User · Answer

You can use the Apache Commons StringUtils substring String str  int start  int end  static method  which is also null safe    See  http   commons apache org proper commons-lang javadocs api-2 6 org apache commons lang StringUtils html substring 28java lang String  20int  20int 29  and http   commons apache org proper commons-lang javadocs api-2 6 src-html org apache commons lang StringUtils html line 1961

User · Answer

If you just want a maximum length  use StringUtils left  No if or ternary    needed   int maxLength   5  StringUtils left string  maxLength     Output         null - gt  null            - gt             a  - gt   a   abcd1234  - gt   abcd1    Left Documentation

User · Answer

For readability  I prefer this   if  inputString length    gt  maxLength        inputString   inputString substring 0  maxLength       over the accepted answer   int maxLength    inputString length    lt  MAX CHAR  inputString length   MAX CHAR  inputString   inputString substring 0  maxLength

User · Answer

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

[java] Limiting the number of characters in a string, and chopping off the rest

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