Java Complex

Question 1

What does the word static do.

Answer 1

Call a static method using a class name
Math.min(88,86);

Call a non-static method using a reference variable name
Song t2 = new Song(); 
t2.play();
Static doesn't need a NEW object.

Question 2

Syntax for wrapping a primitive

Answer 2

wrapping a value
int i = 288;
Integer iWrap = new Integer(i);

Question 3

Syntax for unwrapping a syntax

Answer 3

unwrapping a value

int unWrapped = iWrap.intValue();

Question 4

List of wrappers

Answer 4

Boolean 
Character 
Byte 
Short 
Integer
Long 
Float 
Double

Question 5

Format of a fomat modifier(%)

Answer 5

%[argument number][flags][width][.precision]type

ex.format(“%,6.1f”, 42.000)

Question 6

Types of Format modifiers

Answer 6

%d decimal
%f floating point
%x hexadecimal
%c character

Question 7

Types of date format modifiers.

Answer 7

The complete date and time %tc String.format(“%tc”, new Date());
Sun Nov 28 14:52:41 MST 2004

Just the time %tr
String.format(“%tr”, new Date());
03:01:47 PM

Day of the week, month and day %tA %tB %td
Date today = new Date();
String.format(“%tA, %tB %td”,today,today,today)
Sunday, November 28

Question 8

WHat does a try/catch do and syntax.

Answer 8

Tells compiler that something may go wrong please prepare for it.

try {
// do risky thing
} catch(Exception ex) { // try to recover
}

Question 9

Syntax for creating a new socket.

Answer 9

Socket chatSocket = new Socket(“196.164.1.103”, 5000)

Question 10

To read data from a socket.

Answer 10

1. Make a Socket connection to the server
Socket chatSocket = new Socket(“127.0.0.1”, 5000);

2. Make an InputStreamReader chained to the Socket’s low-level (connection) input stream
InputStreamReader stream = new InputStreamReader(chatSocket.getInputStream());

3. Make a BufferedReader and read!
BufferedReader reader = new BufferedReader(stream); String message = reader.readLine();

Question 11

To write data to a Socket

Answer 11

1. Make a Socket connection to the server
Socket chatSocket = new Socket(“127.0.0.1”, 5000);
2.Make a PrintWriter chained to the Socket’s low-level (connection) output stream
PrintWriter writer = new PrintWriter(chatSocket.getOutputStream());
3.Write (print) something
writer.println(“message to send”); writer.print(“another message”);