Android™

Call a JavaScript Function Returning a Boolean

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Demonstrates how to call a JavaScript function that returns a boolean. 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 isEven(number) {
    //     return number % 2 === 0;
    // }

    CkStringBuilder sbScript = new CkStringBuilder();
    sbScript.Append("function isEven(number) { return number % 2 === 0; }");

    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 isEven(8)

    CkJsonObject funcCall = new CkJsonObject();

    // Create JSON specifying the function name and arguments

    // {
    //   "name": "isEven",
    //   "args": [ 8 ]
    // }

    funcCall.UpdateString("name","isEven");
    funcCall.UpdateInt("args[0]",8);

    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": "bool",
    //   "value": true
    // }

    boolean retval = result.BoolOf("value");
    Log.i(TAG, String.valueOf(retval));

    // Output:
    // true

  }

  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."
  }
}