An Experienced Programmer’s Introduction to Java - Java Application Development on Linux - page 61

Table 3.2 Useful String methods

Return type Method Description

length()

Returns the length, i.e. number of characters,
in the String .

int

equals(Object obj)

Returns true if the object is a String
object and is equal to the String . (Aside:
the argument takes a generic Object type
rather than only a String object because it's
meant to override the equals() method in
the class Object of which String is a
descendant.) This is the way to compare two
String s to see if they are both holding the
same sequence of characters. Using stringA
== stringB will only tell you if stringA
and stringB are referencing the same object
(pointing to the same location in memory).
What you typically want is
stringA.equals(stringB) .

boolean

equalsIgnoreCase(String str)

Similar to equals() , but this one only
allows a String parameter, and it ignores
the upper/lower case distinction between
letters. For example:

boolean

String sample = "abcdefg";
String sample2 = "AbCdEfG";
sample.equalsIgnoreCase(sample2)

returns true .

toLowerCase()

Returns a string with all characters converted
to lowercase.

String

toUpperCase()

Returns a string with all characters converted
to uppercase.

String

startsWith(String substr)

Returns true if the String starts with the
given substring.

boolean

endsWith(String substr)

Returns true if the String ends with the
given substring.

boolean

substring(int index)

Returns a string starting at position index
to the end of the String .

String