Monday 12 December 2011

string manipulation in java example - Searching for Characters and Substrings in a String


Here are some other String methods for finding characters or substrings within a string. The String class provides accessor methods that return the position within the string of a specific character or substring: indexOf() and lastIndexOf(). The indexOf() methods search forward from the beginning of the string, and the lastIndexOf()methods search backward from the end of the string. If a character or substring is not found, indexOf() and lastIndexOf() return -1.
The String class also provides a search method, contains, that returns true if the string contains a particular character sequence. Use this method when you only need to know that the string contains a character sequence, but the precise location isn't important.
The following table describes the various string search methods.
The Search Methods in the String Class
MethodDescription
int indexOf(int ch)
int lastIndexOf(int ch)		Returns the index of the first (last) occurrence of the specified character.
int indexOf(int ch, int fromIndex)
int lastIndexOf(int ch, int fromIndex)		Returns the index of the first (last) occurrence of the specified character, searching forward (backward) from the specified index.
int indexOf(String str)
int lastIndexOf(String str)		Returns the index of the first (last) occurrence of the specified substring.
int indexOf(String str, int fromIndex)
int lastIndexOf(String str, int fromIndex)		Returns the index of the first (last) occurrence of the specified substring, searching forward (backward) from the specified index.
boolean contains(CharSequence s)Returns true if the string contains the specified character sequence.
Note: CharSequence is an interface that is implemented by the String class. Therefore, you can use a string as an argument for the contains() method.
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