Java

Call a JavaScript Function Returning a String

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Demonstrates how to call a JavaScript function that returns a string. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    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.
        System.out.println(result.emit());

        // Also examine the LastErrorText.
        System.out.println(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.
        System.out.println(result.emit());

        // Also examine the LastErrorText.
        System.out.println(js.lastErrorText());
        return;
        }

    System.out.println(result.emit());

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

    String retval = result.stringOf("value");
    System.out.println(retval);

    // Output:
    // Hello, Michael!
  }
}