How to use InMemoryDexClassLoader?

Question

I'd like to be able to run code not installed as part of an application in memory. I assumed InMemoryDexClassLoader was created precisely for this, so I tried using it to execute a method in the same application (same class, even), but from memory. To do so, I load the APK itself into a buffer, and feed that buffer to InMemoryDexClassLoader. However, I get a ClassNotFoundException.

public class Test {
    public void loadSelf(Context c) {
        try {
            FileInputStream fis = new FileInputStream(c.getApplicationInfo().publicSourceDir);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            int bytesRead;
            byte[] buffer = new byte[1024];
            while ((bytesRead = fis.read(buffer, 0, buffer.length)) != -1) {
                baos.write(buffer, 0, bytesRead);
            }
            baos.flush();
            byte[] dex = baos.toByteArray();
            ByteBuffer bb = ByteBuffer.allocate(dex.length);
            bb.put(dex);
            bb.position(0);
            ClassLoader loader = new InMemoryDexClassLoader(bb, null);
            Class thisClass = loader.loadClass(this.getClass().getName()); //ClassNotFoundException
            Method method = thisClass.getMethod("sayHi", Context.class);
            method.invoke(thisClass.newInstance(), c);
            bb.clear();
            return;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void sayHi(Context c) {
        Toast.makeText(c, "Hi!", Toast.LENGTH_LONG).show();
    }
}

Doing the exact same thing with DexClassLoader works fine! Can anyone understand what's wrong?

//This works fine and shows the Toast
public class Test {
    public void loadSelf(Context c) {
        try {
            ClassLoader loader = new DexClassLoader(c.getApplicationInfo().publicSourceDir, null, null, null);
            Class thisClass = loader.loadClass(this.getClass().getName());
            Method method = thisClass.getMethod("sayHi", Context.class);
            method.invoke(thisClass.newInstance(), c);
            return;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void sayHi(Context c) {
        Toast.makeText(c, "Hi!", Toast.LENGTH_LONG).show();
    }
}

I have exactly the same issue. Have you found any solution? – mvmn Dec 19 '22 at 23:14 — mvmn, Dec 19 '22 at 23:14

score -1 · Answer 1 · answered Apr 20 '20 at 22:09

similar things i've faced

then i added this line

 minifyEnabled true

into that part of app.gradle

 android {
 buildTypes {
    debug {
        minifyEnabled true
        useProguard false
        proguardFiles getDefaultProguardFile('proguard-android.txt')
    }
   }
 }

in addition you can add the dependency belowed

 dependencies {
   compile 'com.android.support:multidex:1.0.0'
}

hope it will help to you

How to use InMemoryDexClassLoader?

1 Answers1