MATLAB with JAVA

Hello everybody,

I am aware that there is a way you can use Java classes in MATLAB, would anyone know how to actually do so and how to draw a simple signal in java class and make it work with MATLAB files??.. I basically want if this idea is possible to write few java classes in JAVA and others in MATLAB for the same project, IS it possible and will be able to integrate it together to behave like one big program. I am asked to use JAVA too even though signals are better used with MATLAB so thought I should use both to have some evidence of Object Oriented Technique

Answer 1

[Chirag Gupta]

I am not sure what you mean by a simple signal in Java. But here is a simple example:

--> Java Code

import java.lang.*;

public class SimpleJavaSignal
{
    public int returnSignal()
    {
        return 56;
    }
}

You compile this into SimpleJavaSignal.class.

Use

javaaddpath('directory where the .class file resides')
a = SimpleJavaSignal(); % Creates an object of the java class
methodsview(a); % displays all the methods
a.returnSignal() % calls the Java method returnSignal

Answer 2

[David Young]

Yes, it's very straightforward: info here.

Answer 3

[Mech Princess]

I tried this and I get the following error in matlab. Any idea why? thanks. ??? Undefined function or variable 'SimpleJavaSignal'.

[Chirag Gupta]

Did you compile the java program into the .class file and add the correct directory to the javaddpath?

You can check directories on the path using: javaclasspath

Answer 4

[Brahim]

Yes, it is possible to integrate Java classes with MATLAB and use both languages in a single project. MATLAB allows you to call Java classes and methods directly from within your MATLAB code, making it feasible to combine the strengths of both languages. This means you can write parts of your project in Java (such as object-oriented structures or logic) and use MATLAB’s advanced signal processing capabilities for signal-related tasks.

Here’s how you can do it:

1. **Creating Java Classes**: Write your Java classes as you normally would. For instance, if you’re creating a simple signal generator, write the necessary Java class to handle that logic.

2. **Compile the Java Classes**: After writing your Java classes, compile them into `.class` or `.jar` files. You’ll need to ensure that these files are accessible to MATLAB.

3. **Accessing Java in MATLAB**: In MATLAB, you can load and instantiate Java classes using the `javaaddpath` function to add your Java files to the MATLAB classpath. For example:

```matlab

javaaddpath('path_to_your_class_or_jar');

myJavaObject = mypackage.MyJavaClass(); % Create an object of your Java class

```

4. **Calling Java Methods in MATLAB**: Once the Java class is loaded, you can call its methods just like you would with any MATLAB object. For example:

```matlab

result = myJavaObject.generateSignal(); % Calls a method to generate a signal

```

5. **Interfacing Signals Between Java and MATLAB**: If your Java class generates or processes signals, you can pass data (such as arrays) back and forth between Java and MATLAB. MATLAB can handle Java objects and primitive types like arrays, making integration seamless.

6. **Mixing MATLAB and Java for Object-Oriented Techniques**: This hybrid approach allows you to demonstrate the use of object-oriented techniques by structuring your Java classes with proper design patterns and using MATLAB’s functions to handle the computational parts, such as signal processing and visualization.

This combination can behave like one large integrated program. The workflow would typically involve having MATLAB handle the parts where it excels, like signal generation, processing, and analysis, while Java manages object-oriented design and other custom logic. Just make sure to organize your code so that MATLAB and Java classes interact smoothly, and manage file paths and data structures properly.

This approach can provide a robust system and meet your project’s requirements for both MATLAB’s computational power and Java’s object-oriented structure.

[SL: Removed URL that had nothing to do with calling Java from MATLAB.]