How to call a method in java with example eclipse

Jamie 49 Published: 08/12/2024

How to call a method in java with example eclipse

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Calling a Method in Java

Example Code:

public class MyClass {
public static void myMethod(String str) {
System.out.println("Hello, " + str);
}
public static void main(String[] args) {
myMethod("World");
}
}

Step-by-Step Process in Eclipse:

Create a new Java project: Open Eclipse and create a new Java project named "MyJavaProject". Create a new Java class: Right-click on the "src" folder (or any other folder of your choice) and select "New" > "Class". Name the class "MyClass.java" (as shown in the example code above). Write the method and main method: Copy and paste the example code into the "MyClass.java" file. Create a new Java class for testing: Right-click on the "src" folder and select "New" > "Class". Name the class "TestMyClass.java". Call the method from the test class: In the "TestMyClass.java" file, write a main method that calls the myMethod of the MyClass.

public class TestMyClass {
public static void main(String[] args) {
MyClass.myMethod("Eclipse"); // Calling myMethod with an argument
}
}

Run the test class: Right-click on the "TestMyClass.java" file and select "Run As" > "Java Application". The output will be: "Hello, Eclipse". Verify the result: In the Eclipse console, you should see the output message "Hello, Eclipse". This demonstrates that we successfully called a method from another class.

Note: Make sure to adjust the package name and directory structure according to your project's requirements.

How to call a method with parameters from another class in Java?

In Java, you can call a method with parameters from another class using various methods, such as:

Method Invocation: You can directly call the method of another class by creating an instance of that class and invoking the method on it.

    AnotherClass anotherObject = new AnotherClass();
anotherObject.anotherMethod(parameter);

Interface or Abstract Class Implementation: If AnotherClass implements an interface or extends an abstract class, you can use polymorphism to call the method on any object that is an instance of the class.

    AnotherClass anotherObject = new AnotherClass();
SomeInterface someInterface = (SomeInterface)anotherObject;
someInterface.methodFromInterface(parameter);

Reflection: You can also call a method using Java Reflection API, which provides facilities to inspect and manipulate classes at runtime.

    Method method = anotherObject.getClass().getMethod("methodName", parameterTypes);
method.invoke(anotherObject, parameters);

Lambda Expression: If you are using Java 8 or later, you can also call a method using lambda expressions.

    AnotherClass anotherObject = new AnotherClass();
(anotherObject::methodFromAnother) // Call method on anotherObject instance.

Method References: Similar to lambda expression, you can use method reference to call the method of another class.

    AnotherClass anotherObject = new AnotherClass();
MethodReference ref = anotherObject::methodFromAnother;

Inner or Anonymous Class: You can also define an inner or anonymous class that extends AnotherClass and then override the method you want to call.

    AnotherClass anotherObject = new AnotherClass();
someClass anon = new someClass() {
public void methodFromAnother(parameter) {
// Your code here
}
};

Remember, when calling a method of another class, ensure that the method is either public or has an appropriate access modifier (such as default/package-private) if you are trying to call it from within the same package.