How to use ScriptEngineManager in Android?

Question

import android.widget.Toast;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

 public void bEqual(View v) throws ScriptException {

       ScriptEngineManager mgr = new ScriptEngineManager();
       ScriptEngine engine = mgr.getEngineByName("JavaScript");
        String value = inputText.getText().toString();
        Toast.makeText(this,value,Toast.LENGTH_LONG).show();
        try{
            result = (double)engine.eval(value);
            Toast.makeText(this,String.format("%f",result),Toast.LENGTH_SHORT).show();
        }catch(Exception e){
            Toast.makeText(this,"Exception Raised",Toast.LENGTH_SHORT).show();
        }

    }

What is wrong in it? App is exiting when perform this action. It is not showing any errors but app is closing

Answer 1

Easiest way is to use Mozilla Rhino in Android instead[1] because ScriptEngine and it's dependencies would require time consuming setup and headache.

Import the ff:

import org.mozilla.javascript.Context;
import org.mozilla.javascript.Scriptable;
import android.util.Log;

Code you put somewhere in your method:

    Context context = Context.enter(); // 
    context.setOptimizationLevel(-1); // this is required[2]
    Scriptable scope = context.initStandardObjects();
    Object result = context.evaluateString(scope, "18 > 17 and 18 < 100", "<cmd>", 1, null);
    Log.d("your-tag-here", "" + result);

Add it in your gradle dependencies.

implementation group: 'org.mozilla', name: 'rhino', version: '1.7.10'

Reference:

1. Mozilla Rhino
2. Explanation why that line of code is needed
3. Mozilla Rhino's Maven Repository