redirect message to IO stream

How could Java classes direct program messages to the system console, but error messages, say to a file?
The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output could be re-directed:

Stream st = new Stream(new FileOutputStream("output.txt")); 
System.setErr(st);
System.setOut(st);

java socket connect read string

Java - create socket connection to HOST:PORT and read message from there

import java.io.*;
import java.net.*;
import java.util.*;

public class Time_Server_Socket_Test_Java {
    public static void main(String[] args) {
        try {
            Socket s = new Socket(HOST, PORT);//use your own HOST:PORT
            try {
                InputStream inStream = s.getInputStream();
                Scanner in = new Scanner(inStream);

                while (in.hasNextLine()) {
                    String line = in.nextLine();
                    System.out.println(line);
                }
            } finally {
                s.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

How to serialize variables selectively

In a Java class, one has 10 variables. One wants to serialize only 3 variables,how can this be achieved?
->Make variables as 'transient' which are not to be serialized.

maximize a JFrame window in java

How to Maximize a JFrame :

 
    JFrame myFrame = new JFrame();
    myFrame.setVisible(true);
    myFrame.setExtendedState(myFrame.getExtendedState() | JFrame.MAXIMIZED_BOTH);
    

The usage of Java packages.

Explain the usage of Java packages.

A. This is a way to organize files when a project consists of multiple modules. It also helps resolve naming conflicts when different packages have classes with the same names. 

Packages access level also allows you to protect data from being used by the non-authorized classes.

Java: difference between private, protected, and public?

These keywords are for allowing privileges to components such as java methods and variables.
Public: accessible to all classes
Private: accessible only to the class to which they belong
Protected: accessible to the class to which they belong and any subclasses.

Access specifiers are keywords that determines the type of access to the member of a class. These are:
* Public
* Protected
* Private
* Defaults

java show window JFrame JDialog always on top

We have to use this feature of java.awt.Window : Window.alwaysOnTop(boolean); Example code :

import javax.swing.JFrame;
import javax.swing.JLabel;

public class Always_on_Top_JFrame_JAVA{
    public static void main(String[] args) {
        JFrame frame = new JFrame("Title - always on top :D ");
        // Set's the window to be "always on top"
        frame.setAlwaysOnTop( true );

        frame.setLocationByPlatform( true );
        frame.add( new JLabel(" Always on TOP ") );
        frame.pack();
        frame.setVisible( true );
    }
}

Order of catching exception in java

Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written?

A. Yes, it does. The FileNotFoundException is inherited from the IOException. 

Exception's subclasses have to be caught first.

Exception

^

|

IOException

^

|

FileNotFoundException 

So while catching exceptions, we must catch the low level exception first - here : FileNotFoundException .

#The hierarchy in Java Exception framework :

wrapper classes in Java

Describe the wrapper classes in Java.Wrapper class is wrapper around a primitive data type. An instance of a wrapper class contains, or wraps, a primitive value of the corresponding type.

Following table lists the primitive types and the corresponding wrapper classes:

Primitive - Wrapper

boolean  - java.lang.Boolean

byte - java.lang.Byte

char - java.lang.Character

double - java.lang.Double

float - java.lang.Float

int - java.lang.Integer

long - java.lang.Long

short - java.lang.Short

void - java.lang.Void

Java Class as Applet as well as Application

Can you write a Java class that could be used both as an applet as well as an application?
A. Yes. Add a main() method to the applet.