Question

我正在使用示例代码from the webpage，我仍然会收到此错误：

Exception in thread "main" java.lang.ExceptionInInitializerError
    at com.pi4j.io.gpio.RaspiGpioProvider.<init>(RaspiGpioProvider.java:47)
    at com.pi4j.io.gpio.GpioFactory.getDefaultProvider(GpioFactory.java:102)
    at com.pi4j.io.gpio.impl.GpioControllerImpl.<init>(GpioControllerImpl.java:67)
    at com.pi4j.io.gpio.GpioFactory.getInstance(GpioFactory.java:85)
    at test.main(test.java:21)
Caused by: java.lang.NullPointerException
    at com.pi4j.util.NativeLibraryLoader.load(NativeLibraryLoader.java:218)
    at com.pi4j.wiringpi.Gpio.<clinit>(Gpio.java:138)
    ... 5 more

以下是我使用的页面中的代码，我更改的是要测试的类名。

import com.pi4j.io.gpio.GpioController;
import com.pi4j.io.gpio.GpioFactory;
import com.pi4j.io.gpio.GpioPinDigitalInput;
import com.pi4j.io.gpio.PinPullResistance;
import com.pi4j.io.gpio.RaspiPin;
import com.pi4j.io.gpio.event.GpioPinDigitalStateChangeEvent;
import com.pi4j.io.gpio.event.GpioPinListenerDigital;

/**
 * This example code demonstrates how to setup a listener
 * for GPIO pin state changes on the Raspberry Pi.  
 * 
 * @author Robert Savage
 */
public class test {

    public static void main(String args[]) throws InterruptedException {
        System.out.println("<--Pi4J--> GPIO Listen Example ... started.");

        // create gpio controller
        final GpioController gpio = GpioFactory.getInstance();

        // provision gpio pin #02 as an input pin with its internal pull down resistor enabled
        final GpioPinDigitalInput myButton = gpio.provisionDigitalInputPin(RaspiPin.GPIO_02, PinPullResistance.PULL_DOWN);

        // create and register gpio pin listener
        myButton.addListener(new GpioPinListenerDigital() {
            @Override
            public void handleGpioPinDigitalStateChangeEvent(GpioPinDigitalStateChangeEvent event) {
                // display pin state on console
                System.out.println(" --> GPIO PIN STATE CHANGE: " + event.getPin() + " = " + event.getState());
            }

        });

        System.out.println(" ... complete the GPIO #02 circuit and see the listener feedback here in the console.");

        // keep program running until user aborts (CTRL-C)
        for (;;) {
            Thread.sleep(500);
        }

        // stop all GPIO activity/threads by shutting down the GPIO controller
        // (this method will forcefully shutdown all GPIO monitoring threads and scheduled tasks)
        // gpio.shutdown();   <--- implement this method call if you wish to terminate the Pi4J GPIO controller        
    }
}

我正在运行raspbian

Answer 1

我看起来你还没有安装本机库（WiringPi）。您确定，请按照此处的所有内容进行操作：http://pi4j.com/install.html？

pi4j无法使用示例代码进行初始化

1 个答案: