Why i cant have a public class in a non public class?

Question

How can i fix this code that it will work ?

  class Sample {
    public int a;
    private int b;
    int c;
    }
    public class ex {
    public static void main(String[] args) {
        Sample aClass = new Sample();
        aClass.a = 10;
        aClass.b = 10;
        aClass.c = 10;
    }
}

The error i got:

The public type ex must be defined in its own file
The field Sample.b is not visible

`private int b;` - create a setter `setB(int b) {this.b = b;}` - or make in `public` see https://www.geeksforgeeks.org/variable-scope-in-java/ — Scary Wombat, Oct 12 '18 at 05:52
You cant access private variable from another class. You can access the public variable from a different class. Also, you can access the variable with the default modifier (i.e int c) from a different class if the class is in the same package. Have a look at this thread. https://stackoverflow.com/questions/215497/what-is-the-difference-between-public-protected-package-private-and-private-in — Rans, Oct 12 '18 at 05:58

score 1 · Answer 1 · answered Oct 12 '18 at 05:54

You can't access a Private varaible form outside of the class. What you have to do is change private int b; to public int b; or create a public setter method as in one of the comments pointed out.
For further clarification please refer this answer
Hope this helps.

score 0 · Answer 2 · answered Oct 12 '18 at 05:55

0

private members cannot be accessed outside of class directly.

answered Oct 12 '18 at 05:55

Jignesh M. Khatri

1,407
1
14
22

score 0 · Answer 3 · answered Oct 12 '18 at 05:58

class Sample {
    public int a;
    private int b;
    int c;
    public void setB(int b){
     this.b=b;
    }
   }
    public class ex {
    public static void main(String[] args) {
        Sample aClass = new Sample();
        aClass.a = 10;
        aClass.setB(10);//private variable not accessible directly
        aClass.c = 10;
    }
}

score 0 · Answer 4 · answered Oct 12 '18 at 06:00

Variable scope matters here. You can't access private variables out of the scope.

You have two options for this

Make your variables public

class Sample {
 public int a;
 public int b;
 int c;
}

public class ex {
  public static void main(String[] args) {
     Sample aClass = new Sample();
     aClass.a = 10;
     aClass.b = 10;
     aClass.c = 10;
  }
}

Keep your variables private and have getters and setters

class Sample {
 public int a;
 private int b;
 int c;

 public int getB(){
   return this.b;
 }
 public void setB(int val){
   this.b = val;
 }
}

public class ex {
  public static void main(String[] args) {
     Sample aClass = new Sample();
     aClass.a = 10;
     aClass.setB(10);
     aClass.c = 10;
  }
}

score 0 · Answer 5 · answered Oct 12 '18 at 06:03

You have to follow best OOP practices for members. Always create a private members and make a public getters and setters.

public class Sample {

  private int a;
  private int b;
  private int c;

  public int getA() {
    return a;
  }

  public void setA(int a) {
    this.a = a;
  }

  public int getB() {
    return b;
  }

  public void setB(int b) {
    this.b = b;
  }

  public int getC() {
    return c;
  }

  public void setC(int c) {
    this.c = c;
  }
}
public class ex {
  public static void main(String[] args) {
    Sample aClass = new Sample();
    aClass.setA(10);
    aClass.setB(10);
    aClass.setC(10);
  }
}

score 0 · Answer 6 · answered Oct 12 '18 at 06:05

The following concept will solve your problem

public variable like a (you declared as public int a;) can be accessed using an object like obj.a (aClass.a = 10;)
Private variable like b (you declared as private int b;) cannot be accessed directly using an object like obj.b. Private variable can be accessed only within the class i.e you need to write a setter to do that. Following is the complete code you can try to implement

class Sample { public int a; private int b; int c;
```
 public void setb(int b){
 this.b=b;
 }
 }
  public class ex {
   public static void main(String[] args) {
    Sample aClass = new Sample();
    aClass.a = 10;
    aClass.setb(10);
    aClass.c = 10;
    }
    }
```

Why i cant have a public class in a non public class?

6 Answers6