Android™

Call a JavaScript Function Passing an Object Argument

See more JavaScript Examples

Demonstrates how to call a JavaScript function with an argument that is an object. Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    // This is the JavaScript function we'll call:

    // function describeCar(car) {
    // 	console.log(`This is a ${car.year} ${car.make} ${car.model}.`);
    // }

    CkStringBuilder sbScript = new CkStringBuilder();
    sbScript.Append("function describeCar(car) { console.log(`This is a ${car.year} ${car.make} ${car.model}.`); }");

    CkJs js = new CkJs();

    CkJsonObject result = new CkJsonObject();
    result.put_EmitCompact(false);

    // Call Eval to add the function to the context's global object
    success = js.Eval(sbScript,result);
    if (success == false) {
        // Examine the result for an exception.
        Log.i(TAG, result.emit());

        // Also examine the LastErrorText.
        Log.i(TAG, js.lastErrorText());
        return;
        }

    // ------------------------------------------------------------------------------
    // Call the function describeCar(car)

    CkJsonObject funcCall = new CkJsonObject();
    funcCall.put_EmitCompact(false);

    // Create JSON specifying the function name and arguments
    // In this case, there is only 1 argument, and it is an object.

    // {
    //   "name": "describeCar",
    //   "args": [
    //     {
    //       "make": "Toyota",
    //       "model": "Corolla",
    //       "year": 2022
    //     }
    //   ]
    // }

    funcCall.UpdateString("name","describeCar");

    // Create the JSON object that is the argument.
    CkJsonObject arg = new CkJsonObject();
    arg.UpdateString("make","Toyota");
    arg.UpdateString("model","Corolla");
    arg.UpdateInt("year",2022);

    // Create the arguments array.
    CkJsonArray argsArray = new CkJsonArray();
    argsArray.AddObjectCopyAt(0,arg);

    // Add the "args" array to the funcCall.
    funcCall.AppendArrayCopy("args",argsArray);

    Log.i(TAG, funcCall.emit());

    success = js.CallFunction(funcCall,result);
    if (success == false) {
        // Examine the result for an exception.
        Log.i(TAG, result.emit());

        // Also examine the LastErrorText.
        Log.i(TAG, js.lastErrorText());
        return;
        }

    Log.i(TAG, result.emit());

    // The describeCar JavaScript function returns nothing. 
    // Therefore, the result is "undefined".

    // {
    //   "type": "undefined",
    //   "value": "undefined"
    // }

    // However, the function emitted text to the console.

    CkStringBuilder sbOut = new CkStringBuilder();
    js.ConsoleOutputSb(sbOut);
    Log.i(TAG, sbOut.getAsString());

    // Output:
    // This is a 2022 Toyota Corolla.

    // -----------------------------------------------------------
    // Note: If the object argument is simple, this is an alternative
    // and simpler way of creating the funcCall:

    funcCall.Clear();
    funcCall.UpdateString("name","describeCar");
    funcCall.UpdateString("args[0].make","Toyota");
    funcCall.UpdateString("args[0].model","Corolla");
    funcCall.UpdateInt("args[0].year",2022);
    Log.i(TAG, funcCall.emit());

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}