How to execute Java command which would shutdown Raspbian Operating System?

Question

Our team is using the Raspberry Pi. The standard Raspbian OS runs on the device. All code is written in Java.

We are using the Java library package (pi4j). The package listens to the voltage change in GPIO pins.

I want to make Java shut down the Raspberry Pi whenever the Shutdown button is clicked.

Question: how to shut down the Raspberry Pi using Java?

• goobering: Unconfirmed suggestion here.
• goldilocks: There is no java specific method for this beyond just exec("shutdown"), see here: stackoverflow.com/a/25666/1151724
• Havnar: Goldilocs' answer is better than Runtime.getRuntime().exec("sudo shutdown as it's more portable

Answer 1

There looks to be a complete Java example using pi4j here:

import java.io.IOException;
import com.pi4j.io.gpio.GpioController;
import com.pi4j.io.gpio.GpioFactory;
import com.pi4j.io.gpio.GpioPinDigitalInput;
import com.pi4j.io.gpio.GpioPinDigitalOutput;
import com.pi4j.io.gpio.PinPullResistance;
import com.pi4j.io.gpio.PinState;
import com.pi4j.io.gpio.RaspiPin;
import com.pi4j.io.gpio.event.GpioPinDigitalStateChangeEvent;
import com.pi4j.io.gpio.event.GpioPinListener;
import com.pi4j.io.gpio.event.GpioPinListenerDigital;
public class Shutdown {
 public static void main(String[] args) throws InterruptedException {
 final GpioController gpio = GpioFactory.getInstance();
 final GpioPinDigitalInput input = gpio.provisionDigitalInputPin(RaspiPin.GPIO_02, PinPullResistance.PULL_DOWN);
 input.addListener(new GpioPinListenerDigital() {
 @Override
 public void handleGpioPinDigitalStateChangeEvent(GpioPinDigitalStateChangeEvent event) {
 System.out.println(event.getPin() + " = " + event.getState());
 //Wenn der Pin#2 auf High geht, fährt sich der Rasperry Pi runter.
 if (input.getState()==PinState.HIGH) {
 try {
 Process p = Runtime.getRuntime().exec("sudo shutdown -h now");
 p.waitFor();
 } catch (IOException | InterruptedException e) {
 e.printStackTrace();
 }
 }
 }
 });
 while (true) {
 Thread.sleep(1000);
 }
 }
}

• Havnar: you could leave the whole pi4j part out here. Even though Goldilocks answered in a comment, all that is relevant here is Runtime.getRuntime().exec("sudo shutdown -h now");