Thread: Passing Variable between programs

Hi, I am a beginner in Java. Can anyone help me write a program where
Program 1: Takes input from keyboard from user and check whether it is a number
If yes then passes it to Program2 and Program3 esle return message to user saying entered is not a number.
Program 2: Check number for even or odd and return value to Program 1 which inturn display to user.
Program 3: Check number for prime and returns confirmation to program 1 which inturn display to user.

( if programs checks for 0 to 9 is fine, program1, 2 & 3 should be in different files, I mean three '.java' files.
I know that all can be written in one program but I want to learn and understand how to write into multiple codes/projects which can interact)

Case1: if user enters 7

Output should be

User entered is a number
Number entered by user: odd
Number entered by user: Prime

Different .java files are not different programs. A program usually consists of a multitude of classes, where each class is usually defined in its own .java file.
If you actually need communication across programs this could be very very difficult. If you are simply supposed to have several classes it will be quite easy. But you have to elaborate your question.

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Assuming your terminology doesn't accurately reflect the concept you have in mind, sharing info or data among different objects in the same project can be accomplished multiple ways:

1. Pass the data via the Class’ constructor:

// in the sending class
receivingClass = new ReceivingClass( dataToPass );

2. If an instance of the receiving class already exists, use a mutator (or setter) method to communicate the data from the sending class to the receiving class:

// in the sending class:
receivingClass.setDataToPass( dataToPass );

3. Or, if the ReceivingClass object is being used to obtain the data from the SendingClass, use an accessor (or getter) method:

// in the receiving class
dataToPass = sendingClass.getDataToPass();

In the program you've described, I think you'll have an opportunity to use all 3 approaches which may be the assignment's purpose.

Create main method in Program 1 check here whether number or not now create objects of Program 2 and program 3 now call methods of program 2 and 3 by passing the value from program 1 as a parameter.

What did you come up with? Doing homework for nothing is not me. It seems to me you got the problem set. All you need is an algorithm or steps to follow. But in program form. Write it in english first, then in Java codes. It will look clearer. I would like to see it too.

Hi again. This is an example of a simple program on the weather.

It shows you a local variable called tep, reference data type String, and various other public classes in the same package.

//temperature class
public  class UseTemperatureNice {
 
  public static void main(String args[])  {
 TemperatureNice temp = new TemperatureNice();
temp.setNumber(70.0);
temp.setScale(TempScale.FAHRENHEIT);
temp.display();
 
temp.newTemperature(32.0);
temp.display();
temp = new Temperature(TempScale.CELSIUS);
temp.display();
 
temp = new TemperatureNice(2.73,TempScale.KELVIN);
temp.display();
  }
} //end class

--- Update ---

Hi again. This is an example of a simple program on the weather.

It shows you a local variable called temp, reference data type String, and various other public classes in the same package.

//temperature class
public  class UseTemperatureNice {
 
public static void main(String args[])  {
 TemperatureNice temp = new TemperatureNice();
temp.setNumber(70.0);
temp.setScale(TempScale.FAHRENHEIT);
temp.display();
 
temp.newTemperature(32.0);
temp.display();
temp = new Temperature(TempScale.CELSIUS);
temp.display();
 
temp = new TemperatureNice(2.73,TempScale.KELVIN);
temp.display();
  }
} //end class

This thread is three years old. (And the TemperatureNice code is out of a book.)