Methods for changing strings

String concat(String str)
String replace(char oldChar, char newChar)
String toLowerCase()

String toUpperCase()
String trim()

Methods for searching

int indexOf(int ch)
int indexOf(int ch, int fromIndex)
int lastIndexOf(int ch)
int lastIndexOf(int ch, int fromIndex)

int indexOf(String str)
int indexOf(String str, int fromIndex)
int lastIndexOf(String str)
int lastIndexOf(String str,int fromIndex)

Methods for testing

boolean startsWith(String prefix, int toffset)
boolean startsWith(String prefix)

boolean endsWith(String suffix)
boolean equalsIgnoreCase(String anotherString)

Methods for accessing

String substring(int beginIndex)
String substring(int beginIndex, int endIndex)

char charAt(int index)
public char[] toCharArray()