CODEWITHSUNDEEP
java
CaffeineToCode
CaffeineToCode

Reputation: 830

Object method can not access Object variables?

I am trying to master the fundamentals of Java and OOP. From my understanding, if I have an object Circle that is instantiated with the variable radius, and passes that to a double x, should methods of the Object be able to access these?

package classes;

public class Circle {

    Circle(double radius) {
        double x = radius;
    }

    double area() {
        return x * x * 3.1415; // x can't be resolved to a variable
    }

}

Upvotes: 0

Views: 100

Answers (5)

Sam
Sam

Reputation: 149

Try this code : 

       public class Circle {
       private double x =0.0;
        Circle(double radius) {
    this.x = radius;
 }

double area() {
    return this.x *        this.x * Math.PI;
       }

 }

Upvotes: 0

Todd
Todd

Reputation: 31710

In your example, the double x is limited in scope to the constructor. If you move it out to the object level, it will work as you expect.

public class Circle {

    private double x;

    Circle(double radius) {
        this.x = radius;
    }

    double area() {
        return x * x * 3.1415; 
    }

}

Upvotes: 0

terary
terary

Reputation: 1108

After defined at class level use 'this' for readiblity.

public class Circle {
       private double x =0.0;
    Circle(double radius) {
        this.x = radius;
    }

    double area() {
        return this.x * this.x * 3.1415; // x can't be resolved to a variable
    }

}

Upvotes: 0

Christian Tapia
Christian Tapia

Reputation: 34166

Here you have a scope problem. When you declare x inside the constructor, you are telling that it will only be accessible inside it.

You may want to declare it outside:

public class Circle {
    double x;

    Circle(double radius) {
        x = radius;
    }

    ...
}

Upvotes: 0

Reimeus
Reimeus

Reputation: 159844

x is only available within the scope of the Circle constructor. Declare it at class level so it can be accessed by the area method

public class Circle {
    private double x;

    Circle(double radius) {
        this.x = radius;
    }

    ...
}

Upvotes: 3

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