Require non null (#580)

* Replace null checks with Objects.requireNonNull()

* Use PMD rule instead of checkstyle rule

styleguide/pmd-ruleset.xml

@@ -25,4 +25,37 @@
             <property name="checkAll" value="true"/>
         </properties>
     </rule>
+
+    <!-- Custom Rules -->
+
+    <rule name="UseRequireNonNull"
+          message="Use Objects.requireNonNull() instead of throwing a NullPointerException yourself."
+          language="java"
+          class="net.sourceforge.pmd.lang.rule.XPathRule">
+        <description>
+           Use Objects.requireNonNull() instead of throwing a NullPointerException yourself.
+        </description>
+        <properties>
+            <property name="xpath">
+                <value>
+                    <![CDATA[
+                        //IfStatement[child::Expression//NullLiteral]/Statement//ThrowStatement/Expression/PrimaryExpression/PrimaryPrefix/AllocationExpression/ClassOrInterfaceType[@Image='NullPointerException']
+                    ]]>
+                </value>
+            </property>
+        </properties>
+        <priority>3</priority>
+        <example>
+            <![CDATA[
+                public class Example {
+	                public Example(Object example) {
+		                if (example == null) {
+			                throw new NullPointerException();
+		                }
+	                }
+                }
+            ]]>
+        </example>
+    </rule>
+
 </ruleset>

wpilibj/src/athena/java/edu/wpi/first/wpilibj/AnalogAccelerometer.java

@@ -13,6 +13,7 @@ import edu.wpi.first.wpilibj.livewindow.LiveWindow;
 import edu.wpi.first.wpilibj.livewindow.LiveWindowSendable;
 import edu.wpi.first.wpilibj.tables.ITable;
 
+import static java.util.Objects.requireNonNull;
 
 /**
  * Handle operation of an analog accelerometer. The accelerometer reads acceleration directly
@@ -58,10 +59,9 @@ public class AnalogAccelerometer extends SensorBase implements PIDSource, LiveWi
    *                connected to
    */
   public AnalogAccelerometer(AnalogInput channel) {
+    requireNonNull(channel, "Analog Channel given was null");
+
     m_allocatedChannel = false;
-    if (channel == null) {
-      throw new NullPointerException("Analog Channel given was null");
-    }
     m_analogChannel = channel;
     initAccelerometer();
   }

wpilibj/src/athena/java/edu/wpi/first/wpilibj/AnalogGyro.java

@@ -14,6 +14,8 @@ import edu.wpi.first.wpilibj.interfaces.Gyro;
 import edu.wpi.first.wpilibj.livewindow.LiveWindow;
 import edu.wpi.first.wpilibj.livewindow.LiveWindowSendable;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Use a rate gyro to return the robots heading relative to a starting position. The Gyro class
  * tracks the robots heading based on the starting position. As the robot rotates the new heading is
@@ -70,10 +72,9 @@ public class AnalogGyro extends GyroBase implements Gyro, PIDSource, LiveWindowS
    *                on-board channels 0-1.
    */
   public AnalogGyro(AnalogInput channel) {
+    requireNonNull(channel, "AnalogInput supplied to Gyro constructor is null");
+
     m_analog = channel;
-    if (m_analog == null) {
-      throw new NullPointerException("AnalogInput supplied to Gyro constructor is null");
-    }
     initGyro();
     calibrate();
   }
@@ -102,10 +103,9 @@ public class AnalogGyro extends GyroBase implements Gyro, PIDSource, LiveWindowS
    * @param offset  Preset uncalibrated value to use as the gyro offset.
    */
   public AnalogGyro(AnalogInput channel, int center, double offset) {
+    requireNonNull(channel, "AnalogInput supplied to Gyro constructor is null");
+
     m_analog = channel;
-    if (m_analog == null) {
-      throw new NullPointerException("AnalogInput supplied to Gyro constructor is null");
-    }
     initGyro();
     AnalogGyroJNI.setAnalogGyroParameters(m_gyroHandle, kDefaultVoltsPerDegreePerSecond,
                                           offset, center);

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

@@ -11,6 +11,8 @@ import edu.wpi.first.wpilibj.hal.AnalogJNI;
 import edu.wpi.first.wpilibj.hal.FRCNetComm.tResourceType;
 import edu.wpi.first.wpilibj.hal.HAL;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Class to represent a specific output from an analog trigger. This class is used to get the
  * current output value and also as a DigitalSource to provide routing of an output to digital
@@ -66,15 +68,11 @@ public class AnalogTriggerOutput extends DigitalSource {
    * @param outputType An enum that specifies the output on the trigger to represent.
    */
   public AnalogTriggerOutput(AnalogTrigger trigger, final AnalogTriggerType outputType) {
-    if (trigger == null) {
-      throw new NullPointerException("Analog Trigger given was null");
-    }
-    if (outputType == null) {
-      throw new NullPointerException("Analog Trigger Type given was null");
-    }
+    requireNonNull(trigger, "Analog Trigger given was null");
+    requireNonNull(outputType, "Analog Trigger Type given was null");
+
     m_trigger = trigger;
     m_outputType = outputType;
-
     HAL.report(tResourceType.kResourceType_AnalogTriggerOutput,
         trigger.getIndex(), outputType.value);
   }
@@ -86,7 +84,6 @@ public class AnalogTriggerOutput extends DigitalSource {
     if (m_interrupt != 0) {
       cancelInterrupts();
     }
-
   }
 
   /**

wpilibj/src/athena/java/edu/wpi/first/wpilibj/Counter.java

@@ -17,6 +17,8 @@ import edu.wpi.first.wpilibj.hal.HAL;
 import edu.wpi.first.wpilibj.livewindow.LiveWindowSendable;
 import edu.wpi.first.wpilibj.tables.ITable;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Class for counting the number of ticks on a digital input channel.
  *
@@ -108,9 +110,8 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
    */
   public Counter(DigitalSource source) {
     this();
-    if (source == null) {
-      throw new NullPointerException("Digital Source given was null");
-    }
+
+    requireNonNull(source, "Digital Source given was null");
     setUpSource(source);
   }
 
@@ -140,19 +141,16 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
   public Counter(EncodingType encodingType, DigitalSource upSource, DigitalSource downSource,
                  boolean inverted) {
     this(Mode.kExternalDirection);
-    if (encodingType == null) {
-      throw new NullPointerException("Encoding type given was null");
-    }
+
+    requireNonNull(encodingType, "Encoding type given was null");
+    requireNonNull(upSource, "Up Source given was null");
+    requireNonNull(downSource, "Down Source given was null");
+
     if (encodingType != EncodingType.k1X && encodingType != EncodingType.k2X) {
       throw new RuntimeException("Counters only support 1X and 2X quadreature decoding!");
     }
-    if (upSource == null) {
-      throw new NullPointerException("Up Source given was null");
-    }
+
     setUpSource(upSource);
-    if (downSource == null) {
-      throw new NullPointerException("Down Source given was null");
-    }
     setDownSource(downSource);
 
     if (encodingType == EncodingType.k1X) {
@@ -176,9 +174,9 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
    */
   public Counter(AnalogTrigger trigger) {
     this();
-    if (trigger == null) {
-      throw new NullPointerException("The Analog Trigger given was null");
-    }
+
+    requireNonNull(trigger, "The Analog Trigger given was null");
+
     setUpSource(trigger.createOutput(AnalogTriggerType.kState));
   }
 
@@ -238,12 +236,9 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
    * @param triggerType   The analog trigger output that will trigger the counter.
    */
   public void setUpSource(AnalogTrigger analogTrigger, AnalogTriggerType triggerType) {
-    if (analogTrigger == null) {
-      throw new NullPointerException("Analog Trigger given was null");
-    }
-    if (triggerType == null) {
-      throw new NullPointerException("Analog Trigger Type given was null");
-    }
+    requireNonNull(analogTrigger, "Analog Trigger given was null");
+    requireNonNull(triggerType, "Analog Trigger Type given was null");
+
     setUpSource(analogTrigger.createOutput(triggerType));
     m_allocatedUpSource = true;
   }
@@ -292,9 +287,7 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
    * @param source the digital source to count
    */
   public void setDownSource(DigitalSource source) {
-    if (source == null) {
-      throw new NullPointerException("The Digital Source given was null");
-    }
+    requireNonNull(source, "The Digital Source given was null");
 
     if (m_downSource != null && m_allocatedDownSource) {
       m_downSource.free();
@@ -312,12 +305,8 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
    * @param triggerType   The analog trigger output that will trigger the counter.
    */
   public void setDownSource(AnalogTrigger analogTrigger, AnalogTriggerType triggerType) {
-    if (analogTrigger == null) {
-      throw new NullPointerException("Analog Trigger given was null");
-    }
-    if (triggerType == null) {
-      throw new NullPointerException("Analog Trigger Type given was null");
-    }
+    requireNonNull(analogTrigger, "Analog Trigger given was null");
+    requireNonNull(triggerType, "Analog Trigger Type given was null");
 
     setDownSource(analogTrigger.createOutput(triggerType));
     m_allocatedDownSource = true;
@@ -331,9 +320,8 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
    * @param fallingEdge true to count the falling edge
    */
   public void setDownSourceEdge(boolean risingEdge, boolean fallingEdge) {
-    if (m_downSource == null) {
-      throw new RuntimeException(" Down Source must be set before setting the edge!");
-    }
+    requireNonNull(m_downSource, "Down Source must be set before setting the edge!");
+
     CounterJNI.setCounterDownSourceEdge(m_counter, risingEdge, fallingEdge);
   }
 
@@ -539,9 +527,8 @@ public class Counter extends SensorBase implements CounterBase, LiveWindowSendab
    * @param pidSource An enum to select the parameter.
    */
   public void setPIDSourceType(PIDSourceType pidSource) {
-    if (pidSource == null) {
-      throw new NullPointerException("PID Source Parameter given was null");
-    } else if (pidSource != PIDSourceType.kDisplacement && pidSource != PIDSourceType.kRate) {
+    requireNonNull(pidSource, "PID Source Parameter given was null");
+    if (pidSource != PIDSourceType.kDisplacement && pidSource != PIDSourceType.kRate) {
       throw new IllegalArgumentException("PID Source parameter was not valid type: " + pidSource);
     }
 

wpilibj/src/athena/java/edu/wpi/first/wpilibj/Encoder.java

@@ -15,6 +15,8 @@ import edu.wpi.first.wpilibj.livewindow.LiveWindowSendable;
 import edu.wpi.first.wpilibj.tables.ITable;
 import edu.wpi.first.wpilibj.util.AllocationException;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Class to read quadrature encoders.
  *
@@ -131,12 +133,11 @@ public class Encoder extends SensorBase implements CounterBase, PIDSource, LiveW
    */
   public Encoder(final int channelA, final int channelB, boolean reverseDirection,
                  final EncodingType encodingType) {
+    requireNonNull(encodingType, "Given encoding type was null");
+
     m_allocatedA = true;
     m_allocatedB = true;
     m_allocatedI = false;
-    if (encodingType == null) {
-      throw new NullPointerException("Given encoding type was null");
-    }
     m_aSource = new DigitalInput(channelA);
     m_bSource = new DigitalInput(channelB);
     initEncoder(reverseDirection, encodingType);
@@ -193,16 +194,13 @@ public class Encoder extends SensorBase implements CounterBase, PIDSource, LiveW
    *                         if necessary so forward represents positive values.
    */
   public Encoder(DigitalSource sourceA, DigitalSource sourceB, boolean reverseDirection) {
+    requireNonNull(sourceA, "Digital Source A was null");
+    requireNonNull(sourceB, "Digital Source B was null");
+
     m_allocatedA = false;
     m_allocatedB = false;
     m_allocatedI = false;
-    if (sourceA == null) {
-      throw new NullPointerException("Digital Source A was null");
-    }
     m_aSource = sourceA;
-    if (sourceB == null) {
-      throw new NullPointerException("Digital Source B was null");
-    }
     m_bSource = sourceB;
     initEncoder(reverseDirection, EncodingType.k4X);
   }
@@ -241,19 +239,13 @@ public class Encoder extends SensorBase implements CounterBase, PIDSource, LiveW
    */
   public Encoder(DigitalSource sourceA, DigitalSource sourceB, boolean reverseDirection,
                  final EncodingType encodingType) {
+    requireNonNull(sourceA, "Digital Source A was null");
+    requireNonNull(sourceB, "Digital Source B was null");
+    requireNonNull(encodingType, "Given encoding type was null");
+
     m_allocatedA = false;
     m_allocatedB = false;
     m_allocatedI = false;
-    if (encodingType == null) {
-      throw new NullPointerException("Given encoding type was null");
-    }
-    if (sourceA == null) {
-      throw new NullPointerException("Digital Source A was null");
-    }
-    m_aSource = sourceA;
-    if (sourceB == null) {
-      throw new NullPointerException("Digital Source B was null");
-    }
     m_aSource = sourceA;
     m_bSource = sourceB;
     initEncoder(reverseDirection, encodingType);
@@ -274,16 +266,12 @@ public class Encoder extends SensorBase implements CounterBase, PIDSource, LiveW
    */
   public Encoder(DigitalSource sourceA, DigitalSource sourceB, DigitalSource indexSource,
                  boolean reverseDirection) {
+    requireNonNull(sourceA, "Digital Source A was null");
+    requireNonNull(sourceB, "Digital Source B was null");
+
     m_allocatedA = false;
     m_allocatedB = false;
     m_allocatedI = false;
-    if (sourceA == null) {
-      throw new NullPointerException("Digital Source A was null");
-    }
-    m_aSource = sourceA;
-    if (sourceB == null) {
-      throw new NullPointerException("Digital Source B was null");
-    }
     m_aSource = sourceA;
     m_bSource = sourceB;
     m_indexSource = indexSource;

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

@@ -14,6 +14,8 @@ import edu.wpi.first.wpilibj.hal.HAL;
 import edu.wpi.first.wpilibj.hal.I2CJNI;
 import edu.wpi.first.wpilibj.util.BoundaryException;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * I2C bus interface class.
  *
@@ -201,13 +203,12 @@ public class I2C extends SensorBase {
    * @return Transfer Aborted... false for success, true for aborted.
    */
   public boolean read(int registerAddress, int count, byte[] buffer) {
+    requireNonNull(buffer, "Null return buffer was given");
+
     if (count < 1) {
       throw new BoundaryException("Value must be at least 1, " + count + " given");
     }
 
-    if (buffer == null) {
-      throw new NullPointerException("Null return buffer was given");
-    }
     byte[] registerAddressArray = new byte[1];
     registerAddressArray[0] = (byte) registerAddress;
 
@@ -254,14 +255,11 @@ public class I2C extends SensorBase {
    * @return Transfer Aborted... false for success, true for aborted.
    */
   public boolean readOnly(byte[] buffer, int count) {
+    requireNonNull(buffer, "Null return buffer was given");
     if (count < 1) {
       throw new BoundaryException("Value must be at least 1, " + count + " given");
     }
 
-    if (buffer == null) {
-      throw new NullPointerException("Null return buffer was given");
-    }
-
     ByteBuffer dataReceivedBuffer = ByteBuffer.allocateDirect(count);
 
     int retVal = I2CJNI.i2CRead(m_port, (byte) m_deviceAddress, dataReceivedBuffer,

wpilibj/src/athena/java/edu/wpi/first/wpilibj/Preferences.java

@@ -15,6 +15,8 @@ import edu.wpi.first.wpilibj.networktables.NetworkTable;
 import edu.wpi.first.wpilibj.tables.ITable;
 import edu.wpi.first.wpilibj.tables.ITableListener;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * The preferences class provides a relatively simple way to save important values to the roboRIO to
  * access the next time the roboRIO is booted.
@@ -95,9 +97,8 @@ public class Preferences {
    * @throws NullPointerException if value is null
    */
   public void putString(String key, String value) {
-    if (value == null) {
-      throw new NullPointerException("Value is null");
-    }
+    requireNonNull(value, "Provided value was null");
+
     m_table.putString(key, value);
     m_table.setPersistent(key);
   }

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

@@ -318,17 +318,13 @@ public class Relay extends SensorBase implements MotorSafety, LiveWindowSendable
    * @param direction The direction for the relay to operate in
    */
   public void setDirection(Direction direction) {
-    if (direction == null) {
-      throw new NullPointerException("Null Direction was given");
-    }
+    requireNonNull(direction, "Null Direction was given");
     if (m_direction == direction) {
       return;
     }
 
     free();
-
     m_direction = direction;
-
     initRelay();
   }
 

wpilibj/src/athena/java/edu/wpi/first/wpilibj/RobotDrive.java

@@ -109,10 +109,9 @@ public class RobotDrive implements MotorSafety {
    * @param rightMotor the right SpeedController object used to drive the robot.
    */
   public RobotDrive(SpeedController leftMotor, SpeedController rightMotor) {
-    if (leftMotor == null || rightMotor == null) {
-      m_rearLeftMotor = m_rearRightMotor = null;
-      throw new NullPointerException("Null motor provided");
-    }
+    requireNonNull(leftMotor, "Provided left motor was null");
+    requireNonNull(rightMotor, "Provided right motor was null");
+
     m_frontLeftMotor = null;
     m_rearLeftMotor = leftMotor;
     m_frontRightMotor = null;
@@ -204,9 +203,9 @@ public class RobotDrive implements MotorSafety {
    * @param rightStick The joystick to control the right side of the robot.
    */
   public void tankDrive(GenericHID leftStick, GenericHID rightStick) {
-    if (leftStick == null || rightStick == null) {
-      throw new NullPointerException("Null HID provided");
-    }
+    requireNonNull(leftStick, "Provided left stick was null");
+    requireNonNull(rightStick, "Provided right stick was null");
+
     tankDrive(leftStick.getY(), rightStick.getY(), true);
   }
 
@@ -219,9 +218,9 @@ public class RobotDrive implements MotorSafety {
    * @param squaredInputs Setting this parameter to true decreases the sensitivity at lower speeds
    */
   public void tankDrive(GenericHID leftStick, GenericHID rightStick, boolean squaredInputs) {
-    if (leftStick == null || rightStick == null) {
-      throw new NullPointerException("Null HID provided");
-    }
+    requireNonNull(leftStick, "Provided left stick was null");
+    requireNonNull(rightStick, "Provided right stick was null");
+
     tankDrive(leftStick.getY(), rightStick.getY(), squaredInputs);
   }
 
@@ -236,9 +235,9 @@ public class RobotDrive implements MotorSafety {
    */
   public void tankDrive(GenericHID leftStick, final int leftAxis, GenericHID rightStick,
                         final int rightAxis) {
-    if (leftStick == null || rightStick == null) {
-      throw new NullPointerException("Null HID provided");
-    }
+    requireNonNull(leftStick, "Provided left stick was null");
+    requireNonNull(rightStick, "Provided right stick was null");
+
     tankDrive(leftStick.getRawAxis(leftAxis), rightStick.getRawAxis(rightAxis), true);
   }
 
@@ -254,9 +253,9 @@ public class RobotDrive implements MotorSafety {
    */
   public void tankDrive(GenericHID leftStick, final int leftAxis, GenericHID rightStick,
                         final int rightAxis, boolean squaredInputs) {
-    if (leftStick == null || rightStick == null) {
-      throw new NullPointerException("Null HID provided");
-    }
+    requireNonNull(leftStick, "Provided left stick was null");
+    requireNonNull(rightStick, "Provided right stick was null");
+
     tankDrive(leftStick.getRawAxis(leftAxis), rightStick.getRawAxis(rightAxis), squaredInputs);
   }
 
@@ -545,9 +544,8 @@ public class RobotDrive implements MotorSafety {
    * @param rightOutput The speed to send to the right side of the robot.
    */
   public void setLeftRightMotorOutputs(double leftOutput, double rightOutput) {
-    if (m_rearLeftMotor == null || m_rearRightMotor == null) {
-      throw new NullPointerException("Null motor provided");
-    }
+    requireNonNull(m_rearLeftMotor, "Provided left motor was null");
+    requireNonNull(m_rearRightMotor, "Provided right motor was null");
 
     if (m_frontLeftMotor != null) {
       m_frontLeftMotor.set(limit(leftOutput) * m_maxOutput);

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

@@ -13,6 +13,8 @@ import edu.wpi.first.wpilibj.livewindow.LiveWindow;
 import edu.wpi.first.wpilibj.livewindow.LiveWindowSendable;
 import edu.wpi.first.wpilibj.tables.ITable;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Ultrasonic rangefinder class. The Ultrasonic rangefinder measures absolute distance based on the
  * round-trip time of a ping generated by the controller. These sensors use two transducers, a
@@ -160,9 +162,9 @@ public class Ultrasonic extends SensorBase implements PIDSource, LiveWindowSenda
    * @param units       The units returned in either kInches or kMilliMeters
    */
   public Ultrasonic(DigitalOutput pingChannel, DigitalInput echoChannel, Unit units) {
-    if (pingChannel == null || echoChannel == null) {
-      throw new NullPointerException("Null Channel Provided");
-    }
+    requireNonNull(pingChannel, "Provided ping channel was null");
+    requireNonNull(echoChannel, "Provided echo channel was null");
+
     m_allocatedChannels = false;
     m_pingChannel = pingChannel;
     m_echoChannel = echoChannel;

wpilibj/src/shared/java/edu/wpi/first/wpilibj/PIDController.java

@@ -16,6 +16,8 @@ import edu.wpi.first.wpilibj.tables.ITable;
 import edu.wpi.first.wpilibj.tables.ITableListener;
 import edu.wpi.first.wpilibj.util.BoundaryException;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Class implements a PID Control Loop.
  *
@@ -116,9 +118,8 @@ public class PIDController implements PIDInterface, LiveWindowSendable, Controll
     private PIDController m_controller;
 
     public PIDTask(PIDController controller) {
-      if (controller == null) {
-        throw new NullPointerException("Given PIDController was null");
-      }
+      requireNonNull(controller, "Given PIDController was null");
+
       m_controller = controller;
     }
 
@@ -143,13 +144,8 @@ public class PIDController implements PIDInterface, LiveWindowSendable, Controll
   @SuppressWarnings("ParameterName")
   public PIDController(double Kp, double Ki, double Kd, double Kf, PIDSource source,
                        PIDOutput output, double period) {
-
-    if (source == null) {
-      throw new NullPointerException("Null PIDSource was given");
-    }
-    if (output == null) {
-      throw new NullPointerException("Null PIDOutput was given");
-    }
+    requireNonNull(source, "Null PIDSource was given");
+    requireNonNull(output, "Null PIDOutput was given");
 
     m_controlLoop = new java.util.Timer();
     m_setpointTimer = new Timer();

wpilibj/src/shared/java/edu/wpi/first/wpilibj/command/CommandGroup.java

@@ -10,6 +10,8 @@ package edu.wpi.first.wpilibj.command;
 import java.util.Enumeration;
 import java.util.Vector;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * A {@link CommandGroup} is a list of commands which are executed in sequence.
  *
@@ -153,10 +155,8 @@ public class CommandGroup extends Command {
    * @throws IllegalArgumentException     if command is null
    */
   public final synchronized void addParallel(Command command) {
+    requireNonNull(command, "Provided command was null");
     validate("Can not add new command to command group");
-    if (command == null) {
-      throw new NullPointerException("Given null command");
-    }
 
     command.setParent(this);
 
@@ -193,13 +193,11 @@ public class CommandGroup extends Command {
    * @throws IllegalArgumentException     if command is null
    */
   public final synchronized void addParallel(Command command, double timeout) {
-    validate("Can not add new command to command group");
-    if (command == null) {
-      throw new NullPointerException("Given null command");
-    }
+    requireNonNull(command, "Provided command was null");
     if (timeout < 0) {
       throw new IllegalArgumentException("Can not be given a negative timeout");
     }
+    validate("Can not add new command to command group");
 
     command.setParent(this);
 

wpilibj/src/shared/java/edu/wpi/first/wpilibj/smartdashboard/SendableChooser.java

@@ -13,6 +13,8 @@ import edu.wpi.first.wpilibj.Sendable;
 import edu.wpi.first.wpilibj.command.Command;
 import edu.wpi.first.wpilibj.tables.ITable;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * The {@link SendableChooser} class is a useful tool for presenting a selection of options to the
  * {@link SmartDashboard}.
@@ -75,9 +77,8 @@ public class SendableChooser<V> implements Sendable {
    * @param object the option
    */
   public void addDefault(String name, V object) {
-    if (name == null) {
-      throw new NullPointerException("Name cannot be null");
-    }
+    requireNonNull(name, "Provided name was null");
+
     m_defaultChoice = name;
     if (m_table != null) {
       m_table.putString(DEFAULT, m_defaultChoice);

wpilibjIntegrationTests/src/main/java/edu/wpi/first/wpilibj/fixtures/MotorEncoderFixture.java

@@ -170,6 +170,7 @@ public abstract class MotorEncoderFixture<T extends SpeedController> implements
    * deallocated.
    */
   @Override
+  @SuppressWarnings("Regexp")
   public boolean teardown() {
     String type;
     if (m_motor != null) {

wpilibjIntegrationTests/src/main/java/edu/wpi/first/wpilibj/test/TestSuite.java

@@ -22,6 +22,7 @@ import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 import java.util.logging.LogManager;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
@@ -43,9 +44,7 @@ public class TestSuite extends AbstractTestSuite {
     // Sets up the logging output
     final InputStream inputStream = TestSuite.class.getResourceAsStream("/logging.properties");
     try {
-      if (inputStream == null) {
-        throw new NullPointerException("./logging.properties was not loaded");
-      }
+      Objects.requireNonNull(inputStream, "./logging.properties was not loaded");
       LogManager.getLogManager().readConfiguration(inputStream);
       Logger.getAnonymousLogger().info("Loaded");
     } catch (final IOException | NullPointerException ex) {