Question

I can’t figure out why I keep getting the following errors with the following code:

HelloWorldApp.java:9: pushScreen(net.rim.device.api.ui.Screen) in net.rim.device.api.ui.UiApplication cannot be applied to (com.beginningblackberry.helloworld.HelloWorldMainScreen)
pushScreen(mainScreen);

HelloWorldMainScreen.java:10: cannot find symbol
symbol : method add(net.rim.device.api.ui.component.LabelField)
location: class com.beginningblackberry.helloworld.HelloWorldMainScreen
add(labelField);

\\HelloWorldApp.java

package com.beginningblackberry.helloworld;

import net.rim.device.api.ui.UiApplication;

class HelloWorldApp extends UiApplication {    
    HelloWorldApp() { 
        HelloWorldMainScreen mainScreen = new HelloWorldMainScreen();
        pushScreen(mainScreen);
}
        public static void main(String[] args){
            HelloWorldApp app = new HelloWorldApp();
            app.enterEventDispatcher();
     }     
}   



\\ HelloWorldMainScreen.java
package com.beginningblackberry.helloworld;

import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.component.LabelField;

class HelloWorldMainScreen {
    HelloWorldMainScreen() {
        LabelField labelField = new LabelField("Hello World");
        add(labelField);
        }
} 

Answer 1

in HelloWorldMainScreen you probably need to extend some other class or need to provide the implementation of the add()