Fix many errorprone warnings (#1247)

This fixes two real bugs:
- TimedRobot had a m_period that was hiding the IterativeRobotBase m_period
  and was not getting initialized.
- PDPSim was swapping two parameters to getCurrent()

wpilibj/src/main/java/edu/wpi/first/wpilibj/AnalogTrigger.java

@@ -24,7 +24,7 @@ public class AnalogTrigger extends SendableBase {
   /**
    * Exceptions dealing with improper operation of the Analog trigger.
    */
-  public class AnalogTriggerException extends RuntimeException {
+  public static class AnalogTriggerException extends RuntimeException {
     /**
      * Create a new exception with the given message.
      *

wpilibj/src/main/java/edu/wpi/first/wpilibj/AnalogTriggerOutput.java

@@ -44,7 +44,7 @@ public class AnalogTriggerOutput extends DigitalSource {
   /**
    * Exceptions dealing with improper operation of the Analog trigger output.
    */
-  public class AnalogTriggerOutputException extends RuntimeException {
+  public static class AnalogTriggerOutputException extends RuntimeException {
     /**
      * Create a new exception with the given message.
      *

wpilibj/src/main/java/edu/wpi/first/wpilibj/DriverStation.java

@@ -34,12 +34,12 @@ public class DriverStation {
    */
   public static final int kJoystickPorts = 6;
 
-  private class HALJoystickButtons {
+  private static class HALJoystickButtons {
     public int m_buttons;
     public byte m_count;
   }
 
-  private class HALJoystickAxes {
+  private static class HALJoystickAxes {
     public float[] m_axes;
     public short m_count;
 
@@ -48,7 +48,7 @@ public class DriverStation {
     }
   }
 
-  private class HALJoystickPOVs {
+  private static class HALJoystickPOVs {
     public short[] m_povs;
     public short m_count;
 

wpilibj/src/main/java/edu/wpi/first/wpilibj/I2C.java

@@ -100,7 +100,7 @@ public class I2C implements AutoCloseable {
    * @param receiveSize  Number of bytes to read from the device.
    * @return Transfer Aborted... false for success, true for aborted.
    */
-  @SuppressWarnings("PMD.CyclomaticComplexity")
+  @SuppressWarnings({"PMD.CyclomaticComplexity", "ByteBufferBackingArray"})
   public synchronized boolean transaction(ByteBuffer dataToSend, int sendSize,
                                           ByteBuffer dataReceived, int receiveSize) {
     if (dataToSend.hasArray() && dataReceived.hasArray()) {
@@ -191,6 +191,7 @@ public class I2C implements AutoCloseable {
    * @param size The number of data bytes to write.
    * @return Transfer Aborted... false for success, true for aborted.
    */
+  @SuppressWarnings("ByteBufferBackingArray")
   public synchronized boolean writeBulk(ByteBuffer data, int size) {
     if (data.hasArray()) {
       return writeBulk(data.array(), size);
@@ -246,6 +247,7 @@ public class I2C implements AutoCloseable {
    * @param buffer          A buffer to store the data read from the device.
    * @return Transfer Aborted... false for success, true for aborted.
    */
+  @SuppressWarnings("ByteBufferBackingArray")
   public boolean read(int registerAddress, int count, ByteBuffer buffer) {
     if (count < 1) {
       throw new BoundaryException("Value must be at least 1, " + count + " given");
@@ -303,6 +305,7 @@ public class I2C implements AutoCloseable {
    * @param count  The number of bytes to read in the transaction.
    * @return Transfer Aborted... false for success, true for aborted.
    */
+  @SuppressWarnings("ByteBufferBackingArray")
   public boolean readOnly(ByteBuffer buffer, int count) {
     if (count < 1) {
       throw new BoundaryException("Value must be at least 1, " + count

wpilibj/src/main/java/edu/wpi/first/wpilibj/PIDBase.java

@@ -110,7 +110,7 @@ public class PIDBase extends SendableBase implements PIDInterface, PIDOutput {
   /**
    * Used internally for when Tolerance hasn't been set.
    */
-  public class NullTolerance implements Tolerance {
+  public static class NullTolerance implements Tolerance {
     @Override
     public boolean onTarget() {
       throw new IllegalStateException("No tolerance value set when calling onTarget().");

wpilibj/src/main/java/edu/wpi/first/wpilibj/Relay.java

@@ -34,7 +34,7 @@ public class Relay extends SendableBase implements MotorSafety {
    * This class represents errors in trying to set relay values contradictory to the direction to
    * which the relay is set.
    */
-  public class InvalidValueException extends RuntimeException {
+  public static class InvalidValueException extends RuntimeException {
     /**
      * Create a new exception with the given message.
      *

wpilibj/src/main/java/edu/wpi/first/wpilibj/RobotBase.java

@@ -10,6 +10,7 @@ package edu.wpi.first.wpilibj;
 import java.io.File;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.function.Supplier;
 
@@ -242,12 +243,13 @@ public abstract class RobotBase implements AutoCloseable {
       file.createNewFile();
 
       try (OutputStream output = Files.newOutputStream(file.toPath())) {
-        output.write("Java ".getBytes());
-        output.write(WPILibVersion.Version.getBytes());
+        output.write("Java ".getBytes(StandardCharsets.UTF_8));
+        output.write(WPILibVersion.Version.getBytes(StandardCharsets.UTF_8));
       }
 
     } catch (IOException ex) {
-      ex.printStackTrace();
+      DriverStation.reportError("Could not write FRC_Lib_Version.ini: " + ex.toString(),
+          ex.getStackTrace());
     }
 
     boolean errorOnExit = false;

wpilibj/src/main/java/edu/wpi/first/wpilibj/SPI.java

@@ -22,7 +22,7 @@ public class SPI implements AutoCloseable {
     kOnboardCS0(0), kOnboardCS1(1), kOnboardCS2(2), kOnboardCS3(3), kMXP(4);
 
     @SuppressWarnings("MemberName")
-    public int value;
+    public final int value;
 
     Port(int value) {
       this.value = value;
@@ -188,6 +188,7 @@ public class SPI implements AutoCloseable {
    *
    * @param dataToSend The buffer containing the data to send.
    */
+  @SuppressWarnings("ByteBufferBackingArray")
   public int write(ByteBuffer dataToSend, int size) {
     if (dataToSend.hasArray()) {
       return write(dataToSend.array(), size);
@@ -232,6 +233,7 @@ public class SPI implements AutoCloseable {
    * @param dataReceived The buffer to be filled with the received data.
    * @param size         The length of the transaction, in bytes
    */
+  @SuppressWarnings("ByteBufferBackingArray")
   public int read(boolean initiate, ByteBuffer dataReceived, int size) {
     if (dataReceived.hasArray()) {
       return read(initiate, dataReceived.array(), size);
@@ -269,7 +271,7 @@ public class SPI implements AutoCloseable {
    * @param dataReceived Buffer to receive data from the device.
    * @param size         The length of the transaction, in bytes
    */
-  @SuppressWarnings("PMD.CyclomaticComplexity")
+  @SuppressWarnings({"PMD.CyclomaticComplexity", "ByteBufferBackingArray"})
   public int transaction(ByteBuffer dataToSend, ByteBuffer dataReceived, int size) {
     if (dataToSend.hasArray() && dataReceived.hasArray()) {
       return transaction(dataToSend.array(), dataReceived.array(), size);
@@ -376,6 +378,7 @@ public class SPI implements AutoCloseable {
    * @param timeout timeout in seconds (ms resolution)
    * @return Number of bytes remaining to be read
    */
+  @SuppressWarnings("ByteBufferBackingArray")
   public int readAutoReceivedData(ByteBuffer buffer, int numToRead, double timeout) {
     if (buffer.hasArray()) {
       return readAutoReceivedData(buffer.array(), numToRead, timeout);

wpilibj/src/main/java/edu/wpi/first/wpilibj/SerialPort.java

@@ -8,6 +8,7 @@
 package edu.wpi.first.wpilibj;
 
 import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 
 import edu.wpi.first.wpilibj.hal.FRCNetComm.tResourceType;
 import edu.wpi.first.wpilibj.hal.HAL;
@@ -32,7 +33,7 @@ public class SerialPort implements AutoCloseable {
     kOnboard(0), kMXP(1), kUSB(2), kUSB1(2), kUSB2(3);
 
     @SuppressWarnings("MemberName")
-    public int value;
+    public final int value;
 
     Port(int value) {
       this.value = value;
@@ -316,7 +317,7 @@ public class SerialPort implements AutoCloseable {
    * @return The number of bytes actually written into the port.
    */
   public int writeString(String data) {
-    return write(data.getBytes(), data.length());
+    return write(data.getBytes(StandardCharsets.UTF_8), data.length());
   }
 
   /**

wpilibj/src/main/java/edu/wpi/first/wpilibj/TimedRobot.java

@@ -29,8 +29,6 @@ public class TimedRobot extends IterativeRobotBase {
   // The absolute expiration time
   private double m_expirationTime;
 
-  private double m_period;
-
   /**
    * Constructor for TimedRobot.
    */
@@ -60,6 +58,7 @@ public class TimedRobot extends IterativeRobotBase {
    * Provide an alternate "main loop" via startCompetition().
    */
   @Override
+  @SuppressWarnings("UnsafeFinalization")
   public void startCompetition() {
     robotInit();
 
@@ -93,6 +92,7 @@ public class TimedRobot extends IterativeRobotBase {
   /**
    * Update the alarm hardware to reflect the next alarm.
    */
+  @SuppressWarnings("UnsafeFinalization")
   private void updateAlarm() {
     NotifierJNI.updateNotifierAlarm(m_notifier, (long) (m_expirationTime * 1e6));
   }

wpilibj/src/main/java/edu/wpi/first/wpilibj/Ultrasonic.java

@@ -65,7 +65,7 @@ public class Ultrasonic extends SendableBase implements PIDSource {
    * certainly break. Make sure to disable automatic mode before changing anything with the
    * sensors!!
    */
-  private class UltrasonicChecker extends Thread {
+  private static class UltrasonicChecker extends Thread {
     @Override
     public synchronized void run() {
       Ultrasonic ultrasonic = null;

wpilibj/src/main/java/edu/wpi/first/wpilibj/XboxController.java

@@ -34,7 +34,7 @@ public class XboxController extends GenericHID {
     kStart(8);
 
     @SuppressWarnings({"MemberName", "PMD.SingularField"})
-    private int value;
+    private final int value;
 
     Button(int value) {
       this.value = value;

wpilibj/src/main/java/edu/wpi/first/wpilibj/buttons/Trigger.java

@@ -172,7 +172,7 @@ public abstract class Trigger extends SendableBase {
    * An internal class of {@link Trigger}. The user should ignore this, it is only public to
    * interface between packages.
    */
-  public abstract class ButtonScheduler {
+  public abstract static class ButtonScheduler {
     public abstract void execute();
 
     protected void start() {

wpilibj/src/main/java/edu/wpi/first/wpilibj/command/ConditionalCommand.java

@@ -147,7 +147,7 @@ public abstract class ConditionalCommand extends Command {
   }
 
   @Override
-  protected void _cancel() {
+  protected synchronized void _cancel() {
     if (m_chosenCommand != null && m_chosenCommand.isRunning()) {
       m_chosenCommand.cancel();
     }

wpilibj/src/main/java/edu/wpi/first/wpilibj/util/SortedVector.java

@@ -48,7 +48,7 @@ public class SortedVector<E> extends Vector<E> {
    * @param element The element to add to the Vector
    */
   @Override
-  public void addElement(E element) {
+  public synchronized void addElement(E element) {
     int highBound = size();
     int lowBound = 0;
     while (highBound - lowBound > 0) {
@@ -70,7 +70,7 @@ public class SortedVector<E> extends Vector<E> {
    * Sort the vector.
    */
   @SuppressWarnings("unchecked")
-  public void sort() {
+  public synchronized void sort() {
     Object[] array = new Object[size()];
     copyInto(array);
     removeAllElements();