It seems you have institute training experience. As you are in training, you must be very good at subject. Do one or two dummy projects with realtime reflection, keep fake experience (now a day, it is going much) and appear for interviews. Definitely you get job. To join for corporate training, catch one or two consultants. They get. If you would need I get the names of consultants.

Pass the string to a collection class. Collection classes have methods to find the length of an element where element is your string.

If one thread is wating, JVM calls notify() and more threads are waiting, JVM calls notifyAll().

It is very old question. Reference variable pw is assigned with an anonymous object of PrintWriter returned by getWriter() method.

No answer for this. Most probably designers would like to give different type of storing key/value pairs.

How you can override the same method with the same parameters twice in the same class? It becomes duplication and not overloading.

Any interface does not extend a concrete or abstract class. Interface extends another interface only. Give me one example where you called.

Constructors, static methods and Private methods cannot be abstract.

Because every class can use it.

Java future is bright. No doubt in that. No problem for any branch of B.Tech. I got students of Oceanography.

Config Software Solutions, Chaitanyapuri, Dilsukhnagar, Hyd.

To maintain data persistence and object state.

Yes, deleting/creating file and directory with Java is possible.

Because they are not DS, but they are used by DS.

It is Oracle installation problem, I think so. Contact a hardware engineer to solve the problem.

You mean these:

File class – Retrieving Metadata of File: http://way2java.com/io/file-class-%e2%80%93-retrieveing-metadata-of-file/

File class – Changing File Properties: http://way2java.com/io/file-class-%e2%80%93-changing-file-properties/

Using RequestDispatcher.

Scope of training is very good and ever lasting. You must update your Java knowledge with the time like Hibernate, Spring, Struts, Web services etc. If you very good in these and capable to take laterals, freelancer will be fetching.

Google, you get many free.

See how this helps you.

Applet to Servlet Communication

Applet to Servlet communication is of 2 types:

1. Text-based communication
2. Object-based communication

1) Text based Communication

It is assumed that there exists a table Employee with following fields:

empid number
empname varchar2(15)
empsal number(6, 2)

The source code involves 3 programs:

1. FetchRecordApplet.hmtl for calling applet
2. FetchRecordApplet.java to display an UI to take user’s input of empid and forward it to the servlet. This UI receives the employee particulars from the servlet and displays them in the text fields.
3. FetchRecordServlet.java to receive data from the applet, search for database Employee table, take the values and send them to the applet.

When you run this program, you may get Security Exception. To overcome this, do the following:

Browser menu bar  Tools  Internet Options  Security  Internet  Custom Level  Miscellaneous  Access Data Sources across domains  Select enable

Also with

Browser menu bar  Tools  Internet Options  Security  Local Intranet  Custom Level  Miscellaneous  Access Data Sources across domains  Select enable

1st Program: FetchRecordApplet.html (copy to examplesWebApp)

2nd Program: FetchRecordApplet.java (copy to examplesWebApp)
(for applet file, web.xml file need not be written)

import java.applet.*; import java.awt.*; import java.awt.event.*;
import java.net.*; import java.io.*;

public class FetchRecordApplet extends Applet implements ActionListener
{
TextField idField, nameField, salaryField ;
Button fetchButton ;

public void init( )
{
setLayout(new BorderLayout( ) );
Panel p1 = new Panel( );
p1.setLayout(new GridLayout( 2, 2, 5, 5 ) );
p1.setBackground(Color.cyan);

Panel p2 = new Panel( );
p2.setBackground(Color.pink);
p2.setLayout(new GridLayout( 2, 2, 5, 5 ));

p1.add( new Label(“Enter Employee ID” ));
p1.add( idField = new TextField(15) );
p1.add( new Label(“Click for Details” ));
p1.add( fetchButton = new Button(“Fetch Details” ));
fetchButton.setBackground(Color.yellow);

p2.add( new Label( “Employee Name” ));
p2.add( nameField = new TextField(15));
p2.add( new Label( “Employee Salary” ));
p2.add( salaryField = new TextField(15) );

fetchButton.addActionListener(this);

add(p1, “North”); add(p2, “South”);

}
public void actionPerformed(ActionEvent e)
{
try
{
String str = idField.getText( );

URL u1 = new URL(“http://home:7001/examplesWebApp/
myFetchRecordServlet?t1=”+str);
URLConnection ucon = u1.openConnection( );

InputStream istream = ucon.getInputStream( );

BufferedReader br = new BufferedReader(new
InputStreamReader(istream));
String details[ ] = new String[2];

int i = 0 ;
String str1=””;

while( (str1 = br.readLine( ) ) != null )
{
details[i] = str1 ;
i + + ;
}
br.close( );

nameField.setText(details[0]);
salaryField.setText(details[1]);
}
catch(Exception e1)
{
nameField.setText(“Some Problem” + e1);
salaryField.setText(“Data not received”);
}
}
}

3rd Program: FetchRecordServlet.java (copy to examplesWebApp)

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;

public class FetchRecordServlet extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse res) throws
ServletException, IOException
{
res.setContentType(“text/plain”);
PrintWriter out = res.getWriter( );
String idno = req.getParameter(“t1”);

try
{
Class.forName( “sun.jdbc.odbc.JdbcOdbcDriver” );
Connection con = DriverManager.getConnection(
“jdbc:odbc:snrao”,”scott”,”tiger”);
Statement stmt = con.createStatement( );

ResultSet res1 = stmt.executeQuery(“select *from Employee where
empid=” + idno);
res1.next( );

String name = res1.getString(2);
String salary = res1.getString(3);
out.println(name);
out.println(salary);
out.flush( );

res1.close( ); stmt.close( ); con.close( ); out.close( );
}
catch(ClassNotFoundException e)
{
out.println(“The database driver is not found”);
}
catch(SQLException e)
{
out.println(“Name not found”);
out.println(“Salary not found”);
}
}
}

2. Object-based Communication:

In this objects are passed and retrieved.
The source code involves 3 independent programs.

1st Program: ObjectCommunicationApplet.html

2nd Program: ObjectCommunicationApplet.java ( copy it to the examplesWebApp
directory)
import java.applet.*; import java.awt.*; import java.awt.event.*;
import java.net.*; import java.io.*; import java.util.*;

public class ObjectCommunicationApplet extends Applet implements ActionListener
{
TextField idField, nameField, salaryField ;
Button fetchButton;

public void init( )
{
setLayout(new BorderLayout( ) );
Panel p1 = new Panel( );
p1.setLayout(new GridLayout( 2, 2, 5, 5 ));
p1.setBackground(Color.cyan);

Panel p2 = new Panel( );
p2.setBackground(Color.pink);
p2.setLayout(new GridLayout(2,2,5,5));

p1.add( new Label(“Enter Employee ID” ));
p1.add( idField = new TextField(15) );
p1.add( new Label(“Click for Details” ));
p1.add( fetchButton = new Button(“Fetch Details” ));
fetchButton.setBackground(Color.yellow);

p2.add( new Label( “Employee Name” ));
p2.add( nameField = new TextField(15));
p2.add( new Label( “Employee Salary” ));
p2.add( salaryField = new TextField(15) );

fetchButton.addActionListener(this);

add(p1, “North”); add(p2, “South”);

}
public void actionPerformed(ActionEvent e)
{
try
{
String str = idField.getText( );

URL u1 = new URL(“http://home:7001/examplesWebApp/
myObjectCommunicationServlet”);

URLConnection ucon = u1.openConnection( );

ucon.setUseCaches(false);
ucon.setDoInput(true);
ucon.setDoOutput(true);
ucon.setRequestProperty(“Content-Type”, “application/octet-stream”);
// code to send data(employee id) to the servlet
OutputStream ostream = ucon.getOutputStream( );
ObjectOutputStream oos = new ObjectOutputStream(ostream);

Integer i1 = new Integer( str );

oos.writeObject( i1 );

oos.flush( );
oos.close( );
// code to receive data(employee name and salary) from the servlet

InputStream istream = ucon.getInputStream( );
ObjectInputStream ois = new ObjectInputStream(istream);
// get an object from the servlet that contains the data
Object obj = ois.readObject( );
Vector vect1 = (Vector) obj;
ois.close( );

String name = (String) vect1.elementAt( 0 );
String salary = (String) vect1.elementAt( 1 );

nameField.setText(name);
salaryField.setText(salary);
}
catch(Exception e1)
{
nameField.setText(“Some Problem” + e1);
salaryField.setText(“Data not received”);
}
}
}

3rd Program: ObjectCommunicationServlet.java

import javax.servlet.*; import javax.servlet.http.*; import java.io.*;
import java.sql.*; import java.util.*;

public class ObjectCommunicationServlet extends HttpServlet
{
public void service(HttpServletRequest req, HttpServletResponse res) throws
ServletException, IOException
{
res.setContentType(“text/plain”);

ObjectInputStream ois = new ObjectInputStream(req.getInputStream( ));
ObjectOutputStream oos = new ObjectOutputStream(
res.getOutputStream( ) );
res.setContentType(“application/octet-stream”);

try
{
Integer idno1 = (Integer) ois.readObject( );
String idno = idno1.toString( );

Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”);
Connection con = DriverManager.getConnection( “jdbc:odbc:snrao”,
“scott”,”tiger”);
Statement stmt = con.createStatement( );

ResultSet res1 = stmt.executeQuery(“select *from Employee where
empid = ” +idno);
res1.next( );

String name = res1.getString(2);
String salary = res1.getString(3);

Vector vect2 = new Vector( );
vect2.addElement(name);
vect2.addElement(salary);

oos.writeObject(vect2);

res1.close( ); stmt.close( ); con.close( );
}
catch(ClassNotFoundException e)
{
e.printStackTrace( );
}
catch(SQLException e)
{
e.printStackTrace( );
}
}
}

First solve very simple questions like:

http://way2java.com/java-questions/test-your-java-1/

Choose the version of JDK you want to write the exam.

Then google, you get number of web sites. Solve the questions.

Then, do mock tests available on the sites.

Give with caution \ (back slashes). Use File class pathSeparator.

Maintain Log file. Many tools give this facility.

I do not have code right now. Give search in Google “how to find the systems connected in the network java” you can find a few answers.

You will get reply within three days. Right now I am busy in corporate training.

If you are a C or C++ programmer, you might have found much of the syntax of Java, particularly at the level of operators and statements, to be familiar. Because Java and C are so similar in some ways, it is important for C and C++ programmers to understand where the similarities end. There are a number of important differences between C and Java, which are summarized in the following list:
No preprocessor
Java does not include a preprocessor and does not define any analogs of the define, #include, and #ifdef directives. Constant definitions are replaced with static final fields in Java. (refer java.lang.Math.PI field for an example.) Macro definitions are not available in Java, but advanced compiler technology and inlining has made them less useful. Java does not require an #include directive because Java has no header files. Java class files contain both the class API and the class implementation, and the compiler reads API information from class files as necessary. Java lacks any form of conditional compilation, but its cross-platform portability means that this feature is very rarely needed.
No global variables
Java defines a very clean namespace. Packages contain classes, classes contain fields and methods, and methods contain local variables. But there are no global variables in Java, and, thus, there is no possibility of namespace collisions among those variables.
Well-defined primitive type sizes
All the primitive types in Java have well-defined sizes. In C, the size of short, int, and long types is platform-dependent, which hampers portability.
No pointers
Java classes and arrays are reference types, and references to objects and arrays are same as pointers in C. Unlike C pointers, however, references in Java are entirely opaque. There is no way to convert a reference to a primitive type, and a reference cannot be incremented or decremented. There is no address-of operator like &, dereference operator like * or −>, or sizeof operator. Pointers are a notorious source of bugs. Eliminating them simplifies the language and makes Java programs more robust and secure.
Garbage collection
The Java Virtual Machine performs garbage collection so that Java programmers do not have to explicitly manage the memory used by all objects and arrays. This feature eliminates another entire category of common bugs and all but eliminates memory leaks from Java programs.
No goto statement
Java doesn’t support a goto statement. Use of goto except in certain well-defined circumstances is regarded as poor programming practice. Java adds exception handling and labeled break and continue statements to the flow-control statements offered by C. These are a good substitute for goto.
Variable declarations anywhere
C requires local variable declarations to be made at the beginning of a method or block, while Java allows them anywhere in a method or block. Many programmers prefer to keep all their variable declarations grouped together at the top of a method, however.
Forward references
The Java compiler is smarter than the C compiler, in that it allows methods to be invoked before they are defined. This eliminates the need to declare functions in a header file before defining them in a program file, as is done in C.
Method overloading
Java programs can define multiple methods with the same name, as long as the methods have different parameter lists.
No struct and union types
Java doesn’t support C struct and union types. A Java class can be thought of as an enhanced struct, however.
No enumerated types
Java doesn’t support the enum keyword used in C to define types that consist of fixed sets of named values. This is surprising for a strongly typed language like Java, but there are ways to simulate this feature with object constants.
No bitfields
Java doesn’t support the (infrequently used) ability of C to specify the number of individual bits occupied by fields of a struct.
No typedef
Java doesn’t support the typedef keyword used in C to define aliases for type names. Java’s lack of pointers makes its type-naming scheme simpler and more consistent than C’s, however, so many of the common uses of typedef are not really necessary in Java.
No method pointers
C allows you to store the address of a function in a variable and pass this function pointer to other functions. You cannot do this with Java methods, but you can often achieve similar results by passing an object that implements a particular interface. Also, a Java method can be represented and invoked through a java.lang.reflect.Method object.
No variable-length argument lists
Java doesn’t allow you to define methods such as C’s printf() that take a variable number of arguments. Method overloading allows you to simulate C varargs functions for simple cases, but there’s no general replacement for this feature.
Operators
Java adds a new right shift operator >>> which inserts zeroes at the top end.
The + operator scan be used to concatenate strings.
Java adds another operator instanceof to identify objects.
Operator overloading is not possible in Java.
Classes
Class definitions take the similar form in Java as in C++, but there is no closing semicolon.
There is not scope resolution operator :: in Java.
No destructors in Java
No templates in Java.
Inheritance in Java has the same effect an in C++, but the syntax is different.
Java does not provide direct support for multiple inheritance. We can accomplish
multiple inheritance by using interfaces.
All instance variables have default values
We need not externally define storage for static members like we do in C++.
A class in Java can have an access specifier to determine whether it is visible outside the file.
Arrays
Arrays are quite different in Java. Array boundaries are strictly enforced. Attempting to
read past the end of an array produces an error.
One array can be assigned to another in Java.
Strings
Strings in C/C++ are arrays of characters, terminated by a null character. But strings in
Java are objects.
Strings can be concatenated with + operator.

Differences between C and Java in a nutshell
1. C is a procedural language, Java is object oriented
2. C’s main structuring element are functions in files. Java organizes code in classes and packages, thereby providing better namespaces.
3. C code gets compiled into machine code for a specific CPU. Java code gets compiled into bytecode which is interpreted on a virtual machine (JVM). Java code can get compiled into machine code as well (just-in-time compilers etc.)
4. C does not have exceptions. Errors are handled through return codes.
5. C types like structures (objects without methods) can be allocated on the stack. Java needs to allocate all non-primitives on the heap using expensive memory management functions (e.g. “new”).
6. Arrays and strings in C are not bounds-checked. It is the programmers responsibility to stay within the allocated bounds
7. lets programmers access memory addresses directly through the use of POINTERS. Pointers are variables which contain a memory address. Text (code), data, heap and stack areas are all within a programmers reach. Java lets only the virtual machine access a programs stack, e.g. to perform security checks.
8. Java primitive types are fixed in length. C types can vary per machine. This lets C take maximum use of hardware specifics (e.g. 16 bit register size vs. 32 bit register size). It also creates portability problems.
9. C has a preprocessor and include files. The preprocess works like a macro processor which substitutes macros in the program file.
Top Ten Advantages of Java over C++
Sub-systems can be modelled with packages
Object-oriented systems typically consist of groups of classes, or “sub-systems”, which provide services, rather than a whole bunch of individual classes. The Java package mechanism provides direct support for sub-systems.
All pointer manipulation is done by the compiler
Java takes away the burden of pointer manipulation from the developer. Objects are actually pointers, but there is no need to de-reference objects, take addresses or use a special notation. All that is handled internally by the compiler.
Automatic garbage collection
In C++, the memory for local variables is freed automatically when they go out of scope, but it’s up to developers to free memory which is allocated dynamically. In Java, the run-time system performs automatic garbage collection of dynamically-allocated memory.
No need for header files
C++ classes are typically written in two files: a header file for the class declaration and a separate source file for the implementation. The only use for the header file is so that it can be included in the compilation of other source files which use the class.
Java doesn’t use header files. An entire class is written in a source file. The compiler can look at other files when compiling a class to check function prototypes and access specifiers.
Method functions are “virtual” by default
Designers of a C++ class need to decide which methods could be overriden in the future by derived classes, and declare these methods virtual. In Java, methods are considered virtual by default, unless explicitly declared otherwise. This is more in keeping with the object-oriented principle of keeping derived class information out of base classes.
Rich class library
The standard C++ library is relatively small, consisting mainly of stream operations, plus whatever’s in the C Standard Library. The proposed ANSI standard library adds a lot more functionality, but it’s still some time before it becomes an official standard and becomes supported by all compiler vendors.
Java comes with a rich class library, with support for strings, collection classes, network operations, user interface components, and more.
Robust exception handling
The Java exception mechanism is similar to that in C++, except that Java insists on correct exception specifiers for all functions. This guarantees that the behaviour of a function is predictable because all its exceptions are declared as part of the function declaration.
Standard sizes for basic data types
C++ makes no guarantees about the representation of basic data types. Simple types like int and float are typically implementation based on what’s convenient for the underlying machine. Java specifies standard sizes for its basic data types.
Built-in multi-threading
Java has built-in support for spawning and controlling multiple threads of control in a single process.

Your are 100 right in your option. I will say a small example. The Earth gets gravity due to lead (Pb) metal in the earth. Somebody asked Scientist Einstein if all the lead is removed from earth, then the earth looses its gravity and every object floats in the air. Einstein replied yes definitely all objects float. But the Scientist asked, is it possible to remove entire lead from earth? Same answer for your question.

Java was released in 1995, almost 20 years back. But so far no software company (including the software giants like IBM, Microsoft) did not able to develop JVM or nearer to JVM. That is the secrecy of JVM.

A day may come, as you said, every language may becomes platform-independent. But is it possible?

Very nice observation and good work while learning Java. In non-final, a+b is evaluated as int value and assigned to byte (requires casting). In final variables, a+b is evaluated as byte and assigned byte.

Sorry, not possible.

I am unable to understand your question.

“this” refers the current object or specific (or particular) object. For example,

public class Demo
{
int x;
public void display(int x)
{
this.x = x;
}
}

Now if you call as d1.dipslay(10), then d1 gets a value of 10 and if you call d2.display(20), d2 gets a value of 20. In first case this refers d1 and in second case this refers d2. If display() is static, display() can be called without the help of an object. See this.

public static void display(int x)
{
this.x = x; // error
}

now I call the method directly as display(100) without the help of an object. Then 100 should be given to which object. You tell me. But this refers always an object. For this reason, this is not allowed from static methods.

You are using MouseAdapter class instead of MouseListener. It is required to you to write one more main class AdapterDemo extending Frame. MyMouseAdapter is to be linked to Frame of AdapterDemo.

See this link. It may be helpful to you.

http://way2java.com/awt-components/java-awt-adapters/

They are very different. Access specifier specifies the access restriction and access modification modifies the accessibility. For example, default specifier allows to access by the classes of the same package and final modifier for a method, does not allow the subclass to override. They are discussed here:

http://way2java.com/oops-concepts/specifiers-modifiers/access-specifier-vs-access-modifier-in-java/

Java DS are designed to store only objects from JDK 1.0 to JDK 1.7 (the latest one). But from JDK 1.5, if you store a primitive data type, it is converted into wrapper object automatically (known as autoboxing).

There is no separate Oracle for JDBC. Check your driver and syntax of using it.

Yes, you can create. They are of much theoretical importance. Refer:

http://way2java.com/java-lang/creating-object-without-new-keyword/