String.format（）格式，用于字符串的最后一个字符

Question

is there a possibility to set a String.format argument such that the last N characters of the input are used, ie something like:

String s = String.format("%1${N}s", "abcdef");

so that s contains "def" ? This is common in script languages where you can say

exp = "abcdef"
s = exp[-3]

EDIT

OK, so i don't want to format my data AND handle it when putting it into the String#format function. That's the whole point of the format description here. This format description represents a form of modularity, which is considerably broken if I have to format my input data beforehand although there is a formatter to come...

Answer 1

Unfortunately, even now (y2017) Java 8 Formatter doesn't support "substring".

You can try:

• Freemarker and slicing (substrings) :

   // string 'abcde', evaluates to "bcd" <#assign s="abcde"> ${s[1..3]} 

• Spring Expression Language (SpEL) and expressions methods :

   // string literal 'abcde', evaluates to "bcd" ExpressionParser parser = new SpelExpressionParser(); String sub = parser.parseExpression("'abcde'.substring(2, 4)").getValue(String.class); 

Answer 2

String#substring(int index) does the same thing as your script example:

String a = "abcdef";
String b = String.format("%s", a.substring(3));

Answer 3

I am not clear whether String.format has this kind of function or not. But using functions of String , it can be realized.

    int n = 10;
    String a = "01234567891234";

    // Split into to strings.
    String lastString = a.substring(a.length() - n);
    String firstString = a.substring(0, a.length() - n);

    // Format second string and result is concatenated with first.
    String formattedLastString = String.format("%15s", lastString);
    String formattedString = firstString.concat(formattedLastString);