InstanceOfJava

Return type / return statement in java example

Posted by: Instanceofjava Posted date: June 27, 2015 / comment : 3 concept and program

Return type in java: return statement in java

Basically return type is used in java methods.
Method signature includes this return type.
public int show(){ // }
we will use methods to do a particular task after completion of task if we want to return something to the calling place these return types will be used.
Based on the type of data to be returned will mention it as int , char , float double etc as return type in method signature and return statement should be the last statement of the method body.

In Java, the return statement is used to exit a method and return a value to the calling method. The value returned can be of any data type that is specified in the method's return type.
For example, if a method has a return type of int, it can return an integer value. Here's an example of a simple method that uses the return statement to return an int value:

public int add(int a, int b) {

int sum = a + b;

return sum;

}

In this example, the add method takes two int parameters, a and b, and returns the sum of the two values. The method uses the return statement to return the value of the sum variable back to the calling method.
You can also use return statement without returning any value, in this case method should have void return type.

public void printHelloWorld() {

System.out.println("Hello, World!");

return;

}

In this case the method printHelloWorld doesn't return any value and the calling method doesn't need to assign the return to any variable, just invoking the method will do the job.
It is also worth noting that when a return statement is executed, it immediately exits the current method, regardless of where it is in the method's execution flow. So, any code after a return statement will not be executed.

Type of declaration of methods based on return type and arguments:

1.Method with out return type and without arguments: return statement in java

package com.instanceofjava;
class sample{
public void add(){
int a=40;
int b=50;
int c=a+b;
System.out.println(c);
}
public static void main(String args[]) // ->method prototype.
{

sample obj= new sample();
obj.add();

}
}

2.Method with out return type and with arguments.

package com.instanceofjava;
class sample{
public void add(int a, int b){
int c=a+b;
System.out.println(c);
}
public static void main(String args[]) // ->method prototype.
{

sample obj= new sample();
obj.add(13,24);

}
}

3.Method with return type and without arguments.

package com.instanceofjava;
class sample{
public int add(){
int a=40;
int b=50;
int c=a+b;
return c;
}
public static void main(String args[]) // ->method prototype.
{

sample obj= new sample();
int x=obj.add();
System.out.println(x);

}
}

4.Method with return type and with arguments.

package com.instanceofjava;
class sample{
public int add(int a, int b){
int c=a+b;
return c;
}
public static void main(String args[]) // ->method prototype.
{

sample obj= new sample();
int x=obj.add(1,2);

System.out.println(x);

}
}

If Else Statment in Java

Posted by: Instanceofjava Posted date: June 27, 2015 / comment : 0 concept and program

If statement :

if statement in java is decision making statement in java.
if statement will have a condition and if that condition is true then the corresponding block will be executed.
if(condition){ // }

If condition syntax:

if(condition){
// statements
}

Sample program on if statement:

package com.instanceofjava;
import java.lang.*;
public class ifExample {
public static void main(String[] args) {
if(true){
System.out.println("if condition executed");
}
}

Output:

if condition executed

Java program to compare two numbers in java

package com.instanceofjava;
import java.lang.*;
public class simpleIfExample {
public static void main(String[] args) {
int x= 37;
int y= 37;
if(x==y){
System.out.println(x+ " is equal to " + y);
}
if(x>y){
System.out.println(x+ " is greater than " + y);
}
if(x<y){
System.out.println(x+ " is less than " + y);
}
}

Output:

37 is equal to 37

Else Statement:

if(condition){ //} else { // }

Java program to compare two numbers in java using if else

package com.instanceofjava;
import java.lang.*;
public class ifElseExample {
public static void main(String[] args) {
int x= 37;
int y= 37;
if(x==y){
System.out.println(x+ " is equal to " + y);
}else if(x>y){
System.out.println(x+ " is greater than " + y);
}else{
System.out.println(x+ " is less than " + y);
}
}

Output:

37 is equal to 37

Java program to find leap year or not in java using if else

package com.instanceofjava;
import java.lang.*;
public class ifElseExample {
public static void main(String[] args) {
int year = 2015;
//if year is divisible by 4, it is a leap year
if((year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0)))
System.out.println("Year " + year + " is a leap year");
else
System.out.println( year + " is not a leap year");
}

Output:

2015 is not a leap year

Java program to find even or odd using if else statment

package com.instanceofjava;
import java.lang.*;
public class ifElseEvenOddExample {
public static void main(String[] args) {
int a=10;
if((a%2)==0){
System.out.println(a+"is even number");
}else{
System.out.println(a+"is odd number");
}
}

Output:

10 is even number

Control statements in java with examples

Top 25 Java Basic Interview Questions for Freshers

Posted by: Instanceofjava Posted date: June 27, 2015 / comment : 4 Concept and Interview Questions

Imp Note: Openings for 2024 & 2025 pass outs (MNC) in india. Send your profile to Instanceofjava@gmail.com subject should be: yourName_fresher_resume

1.What is the most Important feature of java?

Java is platform independent language.

2.What do you mean by Platform Independence?

Platform Independence you can run and compile program in one platform and can execute in any other platform.

3.What is JVM(Java Virtual Machine)?

JVM is Java Virtual Machine which is a run time Environment for the compiled java class.

4.What is JIT Compiler?

Just-In-Time(JIT) compiler is used to improve the performance. JIT compiles parts of the byte code that have similar functionality at the same time,

5.Are JVM's Platform Independent?

JVM'S are not platform Independent. JVM'S are platform Specific.

6.What if main method declare as private?

No,It will compile fine but in run time it will error like main method should be in public.cannot find main method.

7.What is platform?

A platform is basically the hardware or software environment in which a program runs.
There are two types of platforms software and hardware.
Java provides software-based platform.

8.What all memory areas are allocated by JVM?

Heap, Stack, Program Counter Register and Native Method Stack

9.What is the base class of all classes?

java.lang.Object

10.What is javac ?

It produces the java byte code from *.java file.
It is the intermediate representation of your source code that contains instructions.

11.Can we mark constructors final?

No, Constructor cannot be declared final.

12.What are two different ways to call garbage collector?

System.gc() OR Runtime.getRuntime().gc().

13.Can we override a static method?

No, we cannot override a static method. Static means class level.

14.Use of finalize() method in java?

finalize() method is used to free the allocated resource.

15.Is it possible to overload main() method of a class?

Yes, we can overload main() method as well.
But every time public static main(String[] args) will be called automatically by JVM.
Other methods need to call explicitly.

16. Does Java support operator overloading?

Operator overloading is not supported in Java.

17.Can I declare a data type inside loop in java?

Any Data type declaration should not be inside the loop. Its possible but not recommended.

18.List two java ID Es?

1.Eclipse, 2.Net beans and 3.IntelliJ

19.Can we inherit the constructors?

No, we cannot inherit constructors.
We can call super class constructors from subclass constructor by using super() call.

20.Can this keyword be assigned null value?

No, this keyword cannot have null values assigned to it.

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Long Wrapper Class

Posted by: Instanceofjava Posted date: June 24, 2015 / comment : 0 Class-Program

Long Wrapper Class:

Long Class is presented in java.lang package.
java.lang.Long class is used to represent primitive Long Value to Long object.

Long Class :

Float Class Definition

public final class Long
extends Number
implements Comparable<Long>

Constructors:

1.Long(long value):

The Constructor Long(long value) represents the specified long argument.

2.Long(String s):

The Constructor Long (String s) represents the long value indicated by the String parameter.

Methods:

1.public static int bitCount(long i); Program:

package com.instanceofjava;
import java.lang.*;
public class LongExample {
public static void main(String[] args) {
long l = 4561;
System.out.println("Number = " + l);
System.out.println("Binary = " + Long.toBinaryString(l));
System.out.println("Number of one bits = " + Long.bitCount(l));
}
}

Output:

Number = 4561
Binary = 1000111010001
Number of one bits = 6

2.public byte byteValue():

This method returns value of long as byte.

Program:

package com.instanceofjava;
import java.lang.*;
public class LongExample {
public static void main(String[] args) {
Long obj = new Long(30);
byte b = obj.byteValue();
System.out.println("Value of b = " + b);
}
}

Output:

Value of b = 30

3.public int compareTo(Long anotherLong):

Program:

package com.instanceofjava;
import java.lang.*;
public class LongExample {
public static void main(String[] args) {
Long a = new Long(63255);
Long b = new Long(71678);
int result= a.compareTo(b);
ifresult> 0) {
System.out.println("a is greater than b");
}
else ifresult< 0) {
System.out.println("a is less than b");
}
else {
System.out.println("a is equal to b");
}
}
}

Output:

a is less than b

4.public static Long decode(String nm) throws NumberFormatException:

Program:

package com.instanceofjava;
import java.lang.*;
public class LongExample{
public static void main(String[] args) {
Long l = new Long(10);
String str = "57820";
System.out.println("Number = " + l.decode(str));
}
}

Output:

57820

Float Wrapper Class

Posted by: Instanceofjava Posted date: June 18, 2015 / comment : 0 Class-Program

Float class is presented in java.lang package
java.lang.Float class is used to represent primitive float value to Float object.

Float Class Definition

public final class Float
extends Number
implements Comparable<Float>

Float Class Constructors

1.public Float(double value)

package com.instanceofjavatutorial;
public class FloatDemo {
public static void main(String[] args) {
Float f = new Float(22.56d);
System.out.println(f);
}
}

Output:

22.56

2.public Float(float value)

package com.instanceofjavatutorial;
public class FloatDemo {
public static void main(String[] args) {
Float f = new Float(22.56f);
System.out.println(f);
}
}

Output:

22.56

3.public Float(String s) throws NumberFormatException

package com.instanceofjavatutorial;
public class FloatDemo {
public static void main(String[] args) {
Float f = new Float("22.56f");
System.out.println(f);
}
}

Output:

22.56

Float Class Methods:

1.public static Float valueOf(String s) throws NumberFormatException

This method used to convert string value to float value. If the string contains non parsable value then it throws NumberFormatException

package com.instanceofjavatutorial;
public class FloatValueOfDemo {
public static void main(String[] args) {
String str="56.32";
Float f = Float.valueOf(str);
System.out.println(f);
}
}

Output:

56.32

2.public String toString()

This method returns String value from Float Object.

package com.instanceofjavatutorial;
public class FloatValueOfDemo {
public static void main(String[] args) {
Float f = new Float("12.3")
String str=f.toString();
System.out.println(str);
}
}

Output:

12.3

3.public static float parseFloat(String s) throws NumberFormatException

This method returns float value from string object. If string doesnt contains parsable float value then throws NumberFormatException

package com.instanceofjavatutorial;
public class FloatDemo {
public static void main(String[] args) {
String str="20";
Float f = Float.parseFloat(str);
System.out.println(f);
}
}

Output:

20.0

Character Class

Posted by: Instanceofjava Posted date: June 18, 2015 / comment : 0 Class-Program

Character class is presented in java.lang package
java.lang.Character class is used to represent primitive character value to character object.

Character Class Definition:

public final class Character
extends Object
implements Serializable, Comparable<Character>

Character Class Constructors:

1. public Character(char value)

Character class having only one constructor which accepts char primitive value.

Java Program to convert char primitive value to Character Object.

package com.instanceofjavatutorial;
public class CharacterDemo {
public static void main(String[] args) {
Character ch = new Character ('a');
System.out.println(ch);
}
}

Output:

Character Class Methods:

1.public char charValue()

This method returns the primitive char value from the Character object.

Java code to get char primitive value from Character Object.

package com.instanceofjavatutorial;
public class CharacterCharValueDemo {
public static void main(String[] args) {
Character ch = new Character ('a');
char c=ch.charValue();
System.out.println(c);
}
}

Output:

2.public static String toString(char c) :

toString(char c) method present in Character class accepts "char" primitive values and returns String objects representing that character.

Java code to convert char primitive value to String object

package com.instanceofjavatutorial;
public class CharactertoStringDemo {
public static void main(String[] args) {
char ch ='I';
String str="";
str=Character.toString(ch);
System.out.println(str);
}
}

Output:

3.public static Character valueOf(char c)

valueOf(char c) is static method present in Character class used to convert char value to Chraracter object.
It accepts char primitive value and returns Character object

Java code to convert char primitive value to String object

package com.instanceofjavatutorial;
public class CharactervalueOfDemo {
public static void main(String[] args) {
char ch ='S';
Character chobj='';
chobj=Character.valueOf(ch);
System.out.println(chobj);
}
}

Output:

4.public static char toUpperCase(char ch)

toUpperCase(char ch) static method present in Character class used to convert a character to uppercase.
It accepts a character and returns same character in uppercase.

Java code to convert char primitive value to uppercase

package com.instanceofjavatutorial;
public class CharacteruppercaseDemo {
public static void main(String[] args) {
char ch ='a';
char c=Character.valueOf(ch);
System.out.println(c);
}
}

Output:

5.public static char toLowerCase(char ch)

toLowerCase(char ch) static method present in Character class used to convert a character to lowercase.
It accepts a character and returns same character in lowercase.

Java code to convert char primitive value to lowercase

package com.instanceofjavatutorial;
public class CharacterlowercaseDemo {
public static void main(String[] args) {
char ch ='L';
char c=Character.valueOf(ch);
System.out.println(c);
}
}

Output:

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