Fundamental Data Types - Java Concepts - page 219

character that you don't want, !, is the character at position 12 (see Figure 4 ).
Therefore, the appropriate substring command is

String sub2 = greeting.substring(7, 12);

Figure 4

Extracting a Substring

It is curious that you must specify the position of the first character that you do want
and then the first character that you don't want. There is one advantage to this setup.
You can easily compute the length of the substring: It is pastEnd - start . For
example, the string ÐWorldÑ has length 12 ɨ 7 62 5.

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160

If you omit the second parameter of the substring method, then all characters
from the starting position to the end of the string are copied. For example,

String tail = greeting.substring(7); // Copies all characters
from position 7 on
sets tail to the string "World!".

If you supply an illegal string position (a negative number, or a value that is larger
than the length of the string), then your program terminates with an error message.

In this section, we have made the assumption that each character in a string occupies
a single position. Unfortunately, that assumption is not quite correct. If you process
strings that contain characters from international alphabets or special symbols, some
characters may occupy two positionsȌsee Advanced Topic 4.5 .

S ELF C HECK

13. Assuming the String variable s holds the value ÐAgentÑ , what is
the effect of the assignments s = s + s.length()?