% cd # remember you can use ls and pwd to figure out where you are in the directory tree % cd cs21 % mkdir week3 % cd week3 % pwd # should list /home/yourusername/cs21/week3 % cp ~newhall/public/cs21/week3/* . % ls StringTest.java
The entire Java API documentation is available off the CS21 homepage under the "Java API Documentation" link in the On-line References section.
Here are some of the String class methods that may be useful in solving the TODO parts (these are copied from the API documentation):
String(String original); Construct a new String initialized to original char charAt(int index); Returns the char value at the specified index. String concat(String str); Concatenates the specified String to the end of this String. (also you can use the + operator with two String arguments to concat them together) boolean contains(CharSequence s); Returns true if and only if this String contains the specified sequence of char values. int indexOf(int ch); Returns the index within this String of the first occurrence of the specified character int length(); Returns the length of this String. String substring(int beginIndex, int endIndex); Returns a new String that is a substring of this String. String toUpperCase(); Converts all of the characters in this String to upper case. String toLowerCase(); Converts all of the characters in this String to lower case int compareTo(String anotherString); Compares two String lexicographically. a negative return value meane the String is less than anotherString positive: its greater than zero: it is equal to int compareToIgnoreCase(String str);
To see the ordering of chars, you can look at the man page for ascii:
% man asciiThe Dec column lists the lexical order of the characters. You can see that the char '1' is less than the char 'A' is less than the char 'a'. So this means that when you compare two strings, a string starting with a numeric char will be less than one starting with an upper case alphabetic char will be less than one starting with a lower case alphabetic char.
The arrow keys can be used to move up and down in the page, and type q to quit out of man.