The Method Is Undefined for the Type Error in Java

Sheeraz Gul Oct 12, 2023

Java Java Error

This tutorial demonstrates Java’s the method is undefined for the type error.

the Method Is Undefined for the Type Error in Java

The error the method is undefined for the type occurs whenever we try to call a method that is not defined in the current class. An example throws the the method is undefined for the type error.

package delftstack;

public class Delftstack1 {
  Delftstack1() {
    System.out.println("Constructor of Delftstack1 class.");
  }
  static void delftstack1_method() {
    System.out.println("method from Delftstack1");
  }
  public static void main(String[] args) {
    delftstack1_method();
    delftstack2_method();
  }
}
class Delftstack2 {
  Delftstack2() {
    System.out.println("Constructor of Delftstack2 class.");
  }
  static void delftstack2_method() {
    System.out.println("method from Delftstack2");
  }
}

The code above calls a method from the class Delftstack2 in the class Delftstack1 directly without creating an instance of the object which will throw the error. See output:

Exception in thread "main" java.lang.Error: Unresolved compilation problem:
    The method Delftstack2_method() is undefined for the type Delftstack1

    at DelftstackDemos/delftstack.Delftstack1.main(Delftstack1.java:12)

To fix this problem, we have to instantiate the object of the Delftstack2 class in the Delftstack1 class. See the solution:

package delftstack;

public class Delftstack1 {
  Delftstack1() {
    System.out.println("Constructor of Delftstack1 class.");
  }
  static void delftstack1_method() {
    System.out.println("method from Delftstack1");
  }
  public static void main(String[] args) {
    delftstack1_method();
    Delftstack2 delftstack2 = new Delftstack2();
    delftstack2.delftstack2_method();
  }
}
class Delftstack2 {
  Delftstack2() {
    System.out.println("Constructor of Delftstack2 class.");
  }
  static void delftstack2_method() {
    System.out.println("method from Delftstack2");
  }
}

The code above will work properly now. See output:

method from Delftstack1
Constructor of Delftstack2 class.
method from Delftstack2

Author: Sheeraz Gul

Sheeraz is a Doctorate fellow in Computer Science at Northwestern Polytechnical University, Xian, China. He has 7 years of Software Development experience in AI, Web, Database, and Desktop technologies. He writes tutorials in Java, PHP, Python, GoLang, R, etc., to help beginners learn the field of Computer Science.

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the Method Is Undefined for the Type Error in Java

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