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Data member programms static non static

//Write a java program to call static with classname
class MyStatic{
static int a;
}
class MyStaticTest{
public static void main(String[] args){
MyStatic.a=10;
System.out.println("My Static value is:"+MyStatic.a);
}
}
Output:
My Static value is:10
Example2:
// Write a java program to verify three to access static data members
class MyStatic{
static int a;
}
class MyStaticTest1{
public static void main(String[] args){
MyStatic s1,s2;
s1=new MyStatic();
s2=null;
MyStatic.a=10;
System.out.println("My Static value is:"+MyStatic.a);
s1.a=20;
System.out.println("My Static value is:"+s1.a);
s2.a=30;
System.out.println("My Static value is:"+s2.a);
}
}
Output:
My Static value is:10
My Static value is:20
My Static value is:30
Example3:
// All static member are stored in class memory
class MyStatic{
static int a;
}
class MyStaticTest1{
public static void main(String[] args){
MyStatic s1,s2;
s1=new MyStatic();
s2=null;
MyStatic.a=10;
s1.a=20;
s2.a=30;
System.out.println("My Static value is:"+s1.a);
System.out.println("My Static value is:"+MyStatic.a);
System.out.println("My Static value is:"+s2.a);
}
}

Output:
My Static value is:30
My Static value is:30
My Static value is:30
Example4:
// write a program to call non static member with a class
class MyStatic{
int a;
}
class MyStaticTest{
public static void main(String[] args){
MyStatic.a=10;
System.out.println("My Static value is:"+MyStatic.a);
}
}
Output:
MyStaticTest.java:6: non-static variable a cannot be referenced from a static co
ntext
MyStatic.a=10;
        ^
MyStaticTest.java:7: non-static variable a cannot be referenced from a static co
ntext
System.out.println("My Static value is:"+MyStatic.a);
                                                 ^
2 errors
Example5:
// Write a program to access Non static data members
class MyStatic{
int a;
}
class MyStaticTest{
public static void main(String[] args){
MyStatic s1 = new MyStatic();
s1.a=10;
System.out.println("My Static value is:"+s1.a);
}}
Output:
My Static value is:10
Example6:
//Write a java to verify can you call non static data members with a reference
class MyStatic{
int a;
}
class MyStaticTest{
public static void main(String[] args){
MyStatic s1 = new MyStatic();
MyStatic s2 = null;
s1.a=10;
System.out.println("My Static value is:"+s1.a);
s2.a=10;
System.out.println("My Static value is:"+s2.a);
}
}
Output:
My Static value is:10
Exception in thread "main" java.lang.NullPointerException

        at MyStaticTest.main(MyStaticTest.java:10)