getClass()

[shana07]

What is the correct sytanx for

getClass()? 

I don't know how to use it as I read java doc it is something like Class<? extends Object> ..what does it mean?
I need to know what class is that and need to do something like this

Class whatClass;
if (whatClass == BigInteger.class) 
{ do something ....}

Please share the correct syntax with me....Thank You

[crossroadsk]

See this example:

class GetTheClass
{
public static void main(String[] args)
{
Object obj = new Object();
String s = new String();
System.out.println(s.getClass());
System.out.println(obj.getClass());
}
}

It returns the classname of the object u used to call that method.

you can use this to know the classname

[shana07]

See this example:

class GetTheClass
{
public static void main(String[] args)
{
Object obj = new Object();
String s = new String();
System.out.println(s.getClass());
System.out.println(obj.getClass());
}
}

It returns the classname of the object u used to call that method.

you can use this to know the classname

thank you...
One more thing can I get something like this:

if (className == jonmath.java.math.MyBigInteger) 
{ //I need to do something only for this class.
  //Do I need to initialize it? something like this?
 // Class intClass = jonmath.java.math.MyBigInteger.class;
}
 

Please help..

[prometheuzz]

thank you...
One more thing can I get something like this:

if (className == jonmath.java.math.MyBigInteger) 
{ //I need to do something only for this class.
  //Do I need to initialize it? something like this?
 // Class intClass = jonmath.java.math.MyBigInteger.class;
}
 

Please help..

You could use

if (className instanceof jonmath.java.math.MyBigInteger) {
    // ...
}

But if your code is going to be full of instanceof operators, you definatelly have a design flaw.

[shana07]

You could use

if (className instanceof jonmath.java.math.MyBigInteger) {
    // ...
}

But if your code is going to be full of instanceof operators, you definatelly have a design flaw.

by doing that - compiler gives error: inverconvertible types
found : java.lang.Class
required: jonmath.java.math.MyBigInteger
Thanks for your reply....

[prometheuzz]

by doing that - compiler gives error: inverconvertible types
found : java.lang.Class
required: jonmath.java.math.MyBigInteger
Thanks for your reply....

Ah, I see. Run this demo to see how the instanceof operator is used:

public class InstanceofDemo {
 
    public static void main(String[] args) {   
        String s = "a string";
        Integer i = new Integer(1);  
        checkWithInstanceof(s);
        checkWithInstanceof(i);
        checkWithInstanceof(String.class);
        checkWithInstanceof(null);
    }
 
    public static void checkWithInstanceof(Object o) {
        if(o instanceof String) {
            System.out.println("'"+o+"' is a String.");
        } 
        else if(o instanceof Integer) {
            System.out.println("'"+o+"' is a Integer.");
        } 
        else if(o instanceof Class) {
            System.out.println("'"+o+"' is a Class.");
        } 
        else {
            System.out.println("'"+o+"' is unknown.");
        }
    }
}