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Reference type instance

Reference type instance:-

Example1:-

class Student
{
String name;
int rollNo;
String address;
Student t;                               //here t is reference of student as a instance variable
public static void main(String[]args)
{

Student s1=new Student();
System.out.println(s1.name);
System.out.println(s1.rollNo);
System.out.println(s1.address);
System.out.println(s1.t);
}
}

Output:-

C:\JAVATECH>javac Student.java
C:\JAVATECH>java Student
null
0
null
null

Example2:-

class Student
{
String name;
int rollNo;
String address;
Student t;
public static void main(String[]args)
{

Student s1=new Student();
System.out.println(s1.name);
System.out.println(s1.rollNo);
System.out.println(s1.address);
System.out.println(s1.t);
s1.t=s1;                                    //here address of object s1 is assign to reference variable t.
System.out.println(s1.t.name);
System.out.println(s1.t.rollNo);
System.out.println(s1.t.address);
System.out.println(s1.t);
}
}

Output:-

C:\JAVATECH>javac Student.java
C:\JAVATECH>java Student
null
0
null
null
null
0
null
Student@52e922

If we pass any reference variable which contains reference of object  to print or println method than output will be classname@Hexadecimal value like in the above output Student@52e922.

Example3:-

class Student
{
String name;
int rollNo;
String address;
Student t=new Student();   /*here each time object created whenever memory  available                        and assign to t.*/
public static void main(String[]args)
{

Student s1=new Student();
System.out.println(s1.name);
System.out.println(s1.rollNo);
System.out.println(s1.address);
}
}

Output:-

C:\JAVATECH>javac Student.java
C:\JAVATECH>java Student
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
………………………………………………
……………………………………………..

Example4:-

class Student
{
String name;
int rollNo;
String address;
static Student t=new Student();  //here only one time object created and assign to t.
public static void main(String[]args)
{

Student s1=new Student();
System.out.println(s1.name);
System.out.println(s1.rollNo);
System.out.println(s1.address);
System.out.println(s1.t);

}
}

Output:-

C:\JAVATECH>javac Student.java
C:\JAVATECH>java Student
null
0
null
Student@52e922

Example5:-

class Student
{
String name;
int rollNo;
String address;
 Student t;
}
class Test
{
public static void main(String[]args)
{

Student s1=new Student();
System.out.println(s1.name);
System.out.println(s1.rollNo);
System.out.println(s1.address);
System.out.println(s1.t);

}
}

Output:-

C:\JAVATECH>javac Test.java
C:\JAVATECH>java Test
null
0
null
null

Example6:-

class Student
{
String name;
int rollNo;
String address;
 Student t=new Student();
}
class Test
{
public static void main(String[]args)
{

Student s1=new Student();
System.out.println(s1.name);
System.out.println(s1.rollNo);
System.out.println(s1.address);
System.out.println(s1.t);

}
}

Output:-

C:\JAVATECH>javac Test.java
C:\JAVATECH>java Test
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
at Student.<init>(Student.java:6)
………………………………………………
……………………………………………..

Example7:-

class Student
{
String name;
int rollNo;
String address;
  static Student t=new Student();
}
class Test
{
public static void main(String[]args)
{

Student s1=new Student();
System.out.println(s1.name);
System.out.println(s1.rollNo);
System.out.println(s1.address);
System.out.println(s1.t);

}
}

Output:-

C:\JAVATECH>javac Test.java
C:\JAVATECH>java Test
null
0
null
null



















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