Attached LEDs to GPIOs 18, 23, and 24, using JavaME 8. 18 and 24 work, but not 23. Why?

Question

I'm new to Raspberry Pi and I have just figured out how to use Java to power LEDs. However, I cannot get GPIO 23 to work. This is my wiring setup.

Here is the java code I am using to power the LEDs.

import java.io.IOException;
import javax.microedition.midlet.MIDlet;
import jdk.dio.DeviceManager;
import jdk.dio.gpio.GPIOPin;


public class LEDBlink extends MIDlet {
    public static final int GREENLED = 23;
    public static final int  REDLED = 24;
    public static final int YELLOWLED = 18;

    @Override
    public void startApp() {
        try {
            GPIOPin red = DeviceManager.open(REDLED);
            GPIOPin green = DeviceManager.open(GREENLED);
            GPIOPin yellow = DeviceManager.open(YELLOWLED);
            red.setValue(true);
            green.setValue(true);
            yellow.setValue(true);

        } catch (IOException ex) {

        }
    }
}

This code worked for GPIO 18 and 24 but not for 23.

I double checked my wiring, replaced all wiring including LED and resistor. I also used the command line to try running the LED. None of that worked.

Does anyone know why I am having trouble?

Answer 1

I figured out that I had not connected the two halves of the breadboard as you can see on the left side. The resistor on the yellow LED was connected to one half of the breadboard, while the resistor connected to the green LED was on connected to the other half of the breadboard and was not hooked up to a ground.