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2. Discussion about???
Why need to navigate to Java code life cycle
JAVA? Data types.
Goals of JAVA. Wrapper Classes.
Features of JAVA. Operators.
C++ Vs JAVA.
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3. Why ‘JAVA’ the programming
language?
The ultimate aim to develop the JAVA programming language
is to implement the words “write once; run anywhere, any time,
forever”.
This is the problem the people meet at that time. The wanted
to have the language that can be run for any platform(Operating
System). This led to the development of JAVA as initial name
Oak. Then JAVA COFFEE, finally renamed as JAVA.
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4. cntd.....
The application needed to be platform independent in some
places. Assume the situation the application is going to be run on
networked systems.
In network many kind of system specification and OS may be
there. In this case the application must be a Platform
independent. Here, JAVA will help us.
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5. Goal of JAVA
It should use the object-oriented programming methodology.
It should allow the same program to be executed on multiple
operating systems.
It should contain built-in support for using computer networks.
It should be designed to execute code from remote sources
securely.
It should be easy to use by selecting what was considered the
good parts of other object-oriented languages.
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6. Features of JAVA
Simple Architecture-neutral
Secure Interpreted
Portable High performance
Object-oriented Automatic Garbage Collection
Robust
Multithreaded
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7. Automatic Garbage Collection
The memory management(allocation and de-allocation) of an
allocated object is done automatically.
If the reference for the object is not available in program, then
the JVM automatically de-allocates the memory for that object.
If this is not done automatically, the programmer must do the
code to manage the memory(allocate and de-allocate).
If not de-allocated by the programmer, then the memory
fragmentation is difficult. Memory leak will occur.
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8. Example code
public static int main(String[] a)
{
System.out.println(“n”+4+34);
return 0;
}
Output???
Error: Main method not found in class sample, please define the main method as:
public static void main(String[] args)
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9. eg: cntd
public static void main(String[] a)
{
System.out.println(“n”+4+34);
System.out.println(34+2+"n");
return 0;
}
Output ??? 434
36
public static void main(String[] a)
{
System.out.println(4+34);
return 0;
}
Output ??? 38
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10. C++ Vs
C++ JAVA
Not a full-fledged object oriented The pure Object oriented language.
language. Because, we can write the
complete program without using
class.
We can write an error free program, Here, we can not complete the
with class and without having any execution without having code within
code within the main(). The program the main().
can be correctly executed completely.
Multiple inheritance is supported. Multiple inheritance is removed.
Operator overloading is available. Not available.
cntd…. 10

11. Virtual functions is available. Indirectly method overriding having
the working of virtual function.
Pointers, references available. References only available.
Platform dependent. Platform independent.
Abstract class avail. Abstract class may be mapped to Interface.
Automatic garbage collection not avail. Available.
Not a strongly typed language. Strongly typed language.
Unicode not supported. Unicode support provided.
Destructor available. finalize() method available instead
destructor.
const final
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12. Function prototype
In C++ the function prototype is ??
return_type function_name(argument_list)
In java for the function prototype concentration on 4 things.
return_type function_name(argument_list) Exception
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13. Code Life cycle
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14. Data Types
All the data types available in C++ available in JAVA. But some
more additions upgraded.
The data width of int and char are upgraded as follows.,
The extra data types are also introduced.
Data type Size(bits)
long 64
int 32
short 16
char 16
New
byte 8
boolean 1
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15. Wrapper Classes
Wrapper classes are special type of classes those bind with the simple
types(Built-in data types).
The Number class is an abstract class that defines a super class that is
implemented by the classes that wrap the numeric types(byte, int,
float, double, long, short).
The class name starts with the uppercase., like Integer, Float.
Each and every wrapper class defines its own methods and constant
data members. The constant data members declared with the names
full of uppercases. eg., Integer.MIN_VALUE.
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16. for example
public static void main(String[] arg)
{
Integer g;
g=45;
System.out.println("ng : “+g);
}
Output
45
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17. Operators
The operators used in C++ all supported in JAVA too.
The I/O stream operators is not possible in java(<<,>>). But
these operators used as a bitwise operators.
Operator overloading can not be done by the user. But in
JAVA, there are some implemented provisions those using the
pre-defined operators with the class.
The arithmetic, relational operators used with the String class
objects.
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18. example…..
public static void main(String[] arg)
{
String fg=“PSG",gh=“Psg";
if((fg+=gh)==fg)
System.out.println("same....n");
else
System.out.println(“Not same....n");
}
Output:
same....
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19. Example
public static void main(String[] arr)
{
int i1=45;
int i2=34;
System.out.println(“Ans is : “+i1+i2);
}
Output???
Ans is : 4534
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20. General example
public static void main(String[] arg)
{
DataInputStream inp=new DataInputStream(System.in);
String mine=inp.readLine();
}
output???
Error: Un handled Exception IOException
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21. Revised
public static void main(String[] arg) throws IOEception
{
DataInputStream inp=new DataInputStream(System.in);
String mine=inp.readLine();
System.out.println(“nString is : ”+mine);
float h=Float.parseFloat(inp.readLine());
System.out.println(“n Float values is : ” +h);
}
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