Android™

Call a JavaScript Function Returning a String

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Demonstrates how to call a JavaScript function that returns a string. 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 greet(name) {
    //     return "Hello, " + name + "!";
    // }

    CkStringBuilder sbScript = new CkStringBuilder();
    sbScript.Append("function greet(name) { return \"Hello, \" + name + \"!\"; }");

    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 greet("Michael")

    CkJsonObject funcCall = new CkJsonObject();

    // Create JSON specifying the function name and arguments

    // {
    //   "name": "greet",
    //   "args": [ "Michael" ]
    // }

    funcCall.UpdateString("name","greet");
    funcCall.UpdateString("args[0]","Michael");

    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());

    // Output:
    // {
    //   "type": "string",
    //   "value": "Hello, Michael!"
    // }

    String retval = result.stringOf("value");
    Log.i(TAG, retval);

    // Output:
    // Hello, Michael!

  }

  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."
  }
}