Why can't I instantiate class ApiContext?

Question

I've downloaded Google Checkout SDK JAR file (checkout-sdk-2.5.1.jar), moved it into project /libs dir [*1], added the library into the project's path. After this I've created a test class that makes test order to sandbox server. Here's the code

import android.widget.TextView;
import com.google.checkout.sdk.commands.ApiContext;
import com.google.checkout.sdk.commands.Environment;
import com.google.checkout.sdk.commands.EnvironmentInterface;

public class Main extends Activity {
    final String MERCHANT_ID = "XXXXXX";
    final String MERCHANT_KEY = "YYYYY";
    final String CURRENCY = "GBP";
    ApiContext API_CONTEXT;

    TextView output;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        API_CONTEXT = new ApiContext(
                Environment.SANDBOX,
                MERCHANT_ID,
                MERCHANT_KEY,
                CURRENCY);

        String result = API_CONTEXT.postCommand
                (EnvironmentInterface.CommandType.ORDER_PROCESSING,
                        "<hello xmlns=\"http://checkout.google.com/schema/2\"/>");

        output = (TextView) findViewById(R.id.output);
        output.setText(result);
    }
}

The main XML has only one element - TextView - that was supposed to display returning XML (which basically contains redirect-url).

However, the app breaks on start with an error:

06-11 18:31:02.372: ERROR/dalvikvm(372): Could not find class 'com.google.checkout.sdk.commands.ApiContext', referenced from method com.example.gc.Main.onCreate 06-11 18:31:02.701: ERROR/AndroidRuntime(372): FATAL EXCEPTION: main java.lang.NoClassDefFoundError: com.google.checkout.sdk.commands.ApiContext

Can this .jar file be used in an Android project? Or I am doing something wrong?

[1]
PS. /libs dir is AFAIK default IntelliJ's dir for external libraries. don't be confused with it.

Answer 1

Could the problem be because .jar file is not meant to be used within Android project? Is there a way to know this?