Question

4. You coded the following class:

public class N extends String, Integer

{

}

When you compile, you get the following message:

N.java:1: ‘{‘ expected

public class N extends String, Integer

                                               ^

1 error

Explain what the problem is and how to fix it.

Answer 1

• Explanation :-
• The Error in the above code is, we can't extend multiple classes at the same time
• That's why we get the Error
• But, we can use implements for extending multiple classes at the same time
• we can use interface and implements for this
• String is a predefined class and Integer is a predefined keyword, so we can't use them as a Classes
• as I mentioned string is a class, but you get a doubt why we can't use the class in a class because already we used that String class in main method  
• That's why I changed the class Names
• Here, I used Main as the main class, don't confuse there... you can name it as you want  
• the name of the file is Main.java

• CODE:-

interface String1 // here we take String1 class
{
void show(); // this is method for String1
}
interface Integer1 // here we take Integer1 class
{
void run(); // this is method for Integer1
}

public class Main implements String1,Integer1 // here we implementing both classes
{
public void show(){ // here we are calling the method show() , to show it's implementation
System.out.println("This is to show method1 for string");
}
public void run(){ // here we are calling the method show() , to show it's implementation
System.out.println("This is to show method2 for Integer ");
}
public static void main(String args[])
{
Main obj = new Main(); //here , we are creating a object for reference variable
obj.show(); // here , we are calling the method using reference variable
obj.run(); // here , we are calling the method using reference variable
  
}
}

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• CODE:-

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​​​​​​​Thank You...!