Detailed introduction to four methods of calling Python using Java

Preface

In modern development, combining the advantages of different programming languages ​​can often achieve twice the result with half the effort. As a strongly typed, object-oriented programming language, Java has unique advantages in performance and maintainability; while Python is known for its concise syntax and rich library ecosystem. In some projects, we may need to call Python scripts or functions in Java code to take advantage of Python's features to handle specific tasks. This article will introduce in detail four methods to call Python in Java, and recommend one of the most commonly used and practical methods.

1. Directly execute Python statements in Java classes

Through the Jython library, Python statements can be executed directly in Java classes. Jython is a Java implementation of Python that allows seamless embedding of Python code into Java programs. With Jython, you can write Python statements in Java code, and even call Python modules and functions.

step:

• download
• exist
• Using Jython'sPythonInterpreterkind

Sample code:

import ;
public class JythonExample {
public static void main(String[] args) {
        PythonInterpreter interpreter
        PythonInterpreter
        Python
PythonInterpreter interpreter = new PythonInterpreter();
        (
        
        interpreter
"print('Hello from Python')");
    }
}
    }
}

Notes:

• Jython only supports Python 2.7. If you need to support Python, you need to consider other methods.

2. Directly call Python scripts in Java

Another way to directly call Python scripts is to use JavaProcessBuilderkind. This method allows us to execute external Python scripts in a Java program and get their output results.

step:

• Make sure that the Python interpreter is installed on the system.
• useProcessBuilderkind

Sample code:

import ;
import ;
public class ProcessBuilderExample {
public static void main(String[] args) {
        try {
            ProcessBuilder pb
            ProcessBuilder
            Process
ProcessBuilder pb = new ProcessBuilder("python", "");
            Process process
            Process
Process process = ();
            BufferedReader in
            BufferedReader
BufferedReader in = new BufferedReader(new InputStreamReader(()));
            String line;
            String line;
            String line;
            String line
            String
while ((line = ()) != null) {
                (line);
            }
        } 
                (line);
            }
        }
                (line);
            }
                (line);
                (line);
                (line
                
                System
catch (Exception e) {
            ();
        }
    }
}
            ();
        }
    }
            ();
        }
            
            
            
            

Notes:

• Python

3. ★★★ Use () to execute Python script files (recommended)

Common ways to call Python scripts in Java are through()Methods execute external processes. Compared withProcessBuilder，RuntimeThe method is simpler and suitable for use in simple scenarios.

step:

• use()Methods execute Python script files.
• passgetInputStream()Get the output result of a Python script.

Sample code:

import ;
import ;
public class RuntimeExample {
public static void main(String[] args) {
try {
            Process process
            Process
Process process = ().exec("python ");
            BufferedReader in = new BufferedReader(new InputStreamReader(()));
            String line;
            while ((line = ()) != null) {
                (line);
            }
        } 
                (line);
            }
        }
                (line);
            }
                (line);
            }
                (line);
                (line);
                (line
                
                
                System
catch (Exception e) {
            ();
        }
    }
}

Reasons for recommendation:

• ()The method is simple and easy to use, suitable for use in scenarios where Python scripts need to be executed quickly.

4. Call functions in Python scripts

In some complex scenarios, it may be necessary to call specific functions in Python scripts in Java. This can be achieved by executing Python scripts, passing parameters or using interactive methods to obtain the function execution results.

step:

• useProcessBuilderor()Execute Python scripts.
• Define functions in Python scripts and pass parameters in Java code.
• Get the return result of function execution and process it in Java code.

Sample code:

import ;
import ;

public class CallPythonFunctionExample {
    public static void main(String[] args) {
        try {
            String[] command = {"python", "", "arg1", "arg2"};
            Process process = ().exec(command);
            BufferedReader in = new BufferedReader(new InputStreamReader(()));
            String line;
            while ((line = ()) != null) {
                (line);
            }
        } catch (Exception e) {
            ();
        }
    }
}

Notes:

• Ensure that the Python script correctly handles the passed parameters and outputs results that can be read by Java programs.

Summarize

There are many implementation methods for calling Python code in Java, from directly executing Python statements to running a complete Python script, each method has its own applicable scenarios. Depending on actual project needs, choosing the right plan will help improve development efficiency. Among them, it is recommended to use()method because it is simpler and easier to implement.

This is the end of this article about the four methods of calling Python using Java. For more information about the content of the four methods of calling Python in Java, please search for my previous article or continue browsing the related articles below. I hope everyone will support me in the future!