Declare a local String variable id and initialize it with your 8-digit student ID in string form. What is the output of the following program segment?
computer science
Description
Question 10
(a)
Declare a
local String variable
id and initialize it with your
8-digit student ID in string form. What is the output of the following program
segment?
String
str = id + " "; // two spaces
System.out.println(str.indexOf("5") + " + " + str.substring(0,2)
+ "\n"
+
str.trim().substring(5)+ "#");
(b)
The class
List below is in java.util. What is the output of the following program
segment?
List<String>
aList = new Vector<>();
aList.add("one");
aList.add("two");
aList.add("three");
aList.add(2,
"one");
aList.remove("one");
System.out.println(aList
+ "\n" + aList.size());
Question 11
Write a method recursive(char
aa, char bb) of a
class Chart which
returns a string starting from aa,
concatenating with characters having values aa+1, aa+2, ... and
ending with bb using recursion, where aa <= bb. For
example, the call aChart.recursive('b',
'e') returns
the string:
bcde
where aChart is an
object of the class Chart.
Question 12
(a)
To find
out the opinions of Hong Kong people on an issue, a series of dialogue boxes
are designed as follows.
(1)
The first
box is:
It is produced by the showConfirmDialog(null,
String message) method
of JOptionPane which
returns an integer (the value of which is YES_OPTION, NO_OPTION or CANCEL_OPTION when the "Yes", "No" or
"Cancel" button is clicked respectively). The message is the string "Do you agree the government should set up an
independent committee to look into the unrest?".
(2)
If
"Cancel" is clicked, the following message is output and the survey
terminates.
(3)
If
"Yes" or "No" is clicked, a new box appears:
If the person clicks "OK", then whatever
entered is stored in a string variable reason.
(4)
If the
person clicks "Cancel", the following message appears and the survey
ends after the person clicks "OK".
Write a Java program segment to produce this series
of dialogue boxes. Remember to declare any variable(s) needed.
