Is it possible to execute a Java code string at runtime in Android?

Question

I want to get a line of Java code from user and execute it in Android. For example:

String strExecutable = " int var; var = 4 + 3"
Object obj = aLibrary.eval(strExecutable);

It is not java script and I want to run a java code.

Is it possible? If yes how?

I have studied links like this. But they are questions about JVM not Android Dalvik.

Android is an OS. You make applications for Android using JAVA — Blackbelt, Mar 27 '13 at 10:39
@blackbelt When we say Android we usually mean Dalvik and its libraries — Bob, Mar 27 '13 at 11:12
I'm not sure about arbitrary Java code, but [this question](http://stackoverflow.com/questions/2226863/whats-a-good-library-for-parsing-mathematical-expressions-in-java) and [this one](http://stackoverflow.com/questions/13747069/is-there-a-mathematical-expression-parsing-library-on-android) seem similar, if the requirements are just simple mathematics. [MVEL](http://mvel.codehaus.org) should handle your example string. — ig0774, Mar 27 '13 at 11:29
If you need something bigger, maybe you should try Rhino Javascript Engine. But if you want to really run Java, I guess it's not possible. Maybe HotStop can do it. — Daniel Monteiro, Mar 27 '13 at 19:58

score 6 · Answer 1 · answered Feb 08 '15 at 19:43

You can try BeanShell! It's super easy and works also on android. Just build your app with jar library.

import bsh.Interpreter;
private void runString(String code){    
    Interpreter interpreter = new Interpreter();
    try {
         interpreter.set("context", this);//set any variable, you can refer to it directly from string
         interpreter.eval(code);//execute code
    }
    catch (Exception e){//handle exception
        e.printStackTrace();
    }
}

But be careful! Using this in production app may be security risk, especially if your app interacts with users data / files.

What do I need to get access to bsh? It says cannot resolve symbol.bsh — vytaute, Aug 05 '22 at 09:13

Khaled.K · Answer 2 · 2016-10-17T05:38:10.773

You can try something like this:

// Code Execute, Khaled A Khunaifer, 27 March 2013
class CodeExcute
{
    public static void execute (String[] commands, String[] headers)
    {
        // build commands into new java file
        try
        {
            FileWriter fstream = new FileWriter("Example.java");
            BufferedWriter out = new BufferedWriter(fstream);

            out.write("");

            for (String header : headers) out.append(header);

            out.append("class Example { public static void main(String args[]) { ");

            for (String cmd : commands) out.append(cmd);

            out.append(" } }");

            out.close();
        }
        catch (Exception e)
        {
            System.err.println("Error: " + e.getMessage());
        }

        // set path, compile, & run
        try
        {
            Process tr = Runtime.getRuntime().exec(
               new String[]{ "java -cp .",
                  "javac Example.java",
                  "java Example" } );
        }
        catch (Exception e)
        {
            System.err.println("Error: " + e.getMessage());
        }

    }
}

Is it possible to execute a Java code string at runtime in Android?

2 Answers2