More consistent instance variable names

Author: manuelbl

java-does-usb/src/main/java/net/codecrete/usb/USB.java

@@ -14,7 +14,8 @@
 
 import java.util.List;
 import java.util.function.Consumer;
-import java.util.stream.Collectors;
+
+import static java.util.stream.Collectors.toList;
 
 /**
  * Provides access to USB devices.
@@ -38,14 +39,14 @@ private static USBDeviceRegistry createInstance() {
         return impl;
     }
 
-    private static USBDeviceRegistry _instance = null;
+    private static USBDeviceRegistry singletonInstance = null;
 
     private static synchronized USBDeviceRegistry instance() {
-        if (_instance == null) {
-            _instance = createInstance();
-            _instance.start();
+        if (singletonInstance == null) {
+            singletonInstance = createInstance();
+            singletonInstance.start();
         }
-        return _instance;
+        return singletonInstance;
     }
 
     // Private, so no instance can be created
@@ -67,43 +68,43 @@ public static List<USBDevice> getAllDevices() {
     }
 
     /**
-     * Gets a list of connected USB devices matching the specified filter.
+     * Gets a list of connected USB devices matching the specified predicate.
      *
-     * @param filter device filter
+     * @param predicate device predicate/filter
      * @return list of USB devices
      */
-    public static List<USBDevice> getDevices(USBDeviceFilter filter) {
-        return instance().getAllDevices().stream().filter(filter::matches).collect(Collectors.toList());
+    public static List<USBDevice> getDevices(USBDevicePredicate predicate) {
+        return instance().getAllDevices().stream().filter(predicate::matches).collect(toList());
     }
 
     /**
-     * Gets a list of connected USB devices matching any of the specified filters.
+     * Gets a list of connected USB devices matching any of the specified predicates/filters.
      *
-     * @param filters list of device filters
+     * @param predicates list of device predicates/filters
      * @return list of USB devices
      */
-    public static List<USBDevice> getDevices(List<USBDeviceFilter> filters) {
-        return instance().getAllDevices().stream().filter(dev -> USBDeviceFilter.matchesAny(dev, filters)).collect(Collectors.toList());
+    public static List<USBDevice> getDevices(List<USBDevicePredicate> predicates) {
+        return instance().getAllDevices().stream().filter(dev -> USBDevicePredicate.matchesAny(dev, predicates)).collect(toList());
     }
 
     /**
-     * Gets the first connected USB device matching the specified filter.
+     * Gets the first connected USB device matching the specified predicate.
      *
-     * @param filter device filter
+     * @param predicate device predicate/filter
      * @return USB device, or {@code null} if no device matches
      */
-    public static USBDevice getDevice(USBDeviceFilter filter) {
-        return instance().getAllDevices().stream().filter(filter::matches).findFirst().orElse(null);
+    public static USBDevice getDevice(USBDevicePredicate predicate) {
+        return instance().getAllDevices().stream().filter(predicate::matches).findFirst().orElse(null);
     }
 
     /**
-     * Gets the first connected USB device matching any of the specified filters.
+     * Gets the first connected USB device matching any of the specified predicates.
      *
-     * @param filters list of device filters
+     * @param predicates list of device predicates/filters
      * @return USB device, or {@code null} if no device matches
      */
-    public static USBDevice getDevice(List<USBDeviceFilter> filters) {
-        return instance().getAllDevices().stream().filter(dev -> USBDeviceFilter.matchesAny(dev, filters)).findFirst().orElse(null);
+    public static USBDevice getDevice(List<USBDevicePredicate> predicates) {
+        return instance().getAllDevices().stream().filter(dev -> USBDevicePredicate.matchesAny(dev, predicates)).findFirst().orElse(null);
     }
 
     /**

java-does-usb/src/main/java/net/codecrete/usb/USBDeviceFilter.java

@@ -20,13 +20,13 @@
  * product ID and serial number is globally unique.
  * </p>
  */
-public class USBDeviceFilter {
-    private Integer vendorId_;
-    private Integer productId_;
-    private Integer classCode_;
-    private Integer subclassCode_;
-    private Integer protocolCode_;
-    private String serialNumber_;
+public class USBDeviceFilter implements USBDevicePredicate {
+    private Integer vid;
+    private Integer pid;
+    private Integer deviceClass;
+    private Integer deviceSubclass;
+    private Integer deviceProtocol;
+    private String serialString;
 
     /**
      * Creates a new instance.
@@ -41,8 +41,8 @@ public USBDeviceFilter() {
      * @param productId product ID
      */
     public USBDeviceFilter(int vendorId, int productId) {
-        vendorId_ = vendorId;
-        productId_ = productId;
+        vid = vendorId;
+        pid = productId;
     }
 
     /**
@@ -53,9 +53,9 @@ public USBDeviceFilter(int vendorId, int productId) {
      * @param serialNumber serial number
      */
     public USBDeviceFilter(int vendorId, int productId, String serialNumber) {
-        vendorId_ = vendorId;
-        productId_ = productId;
-        serialNumber_ = serialNumber;
+        vid = vendorId;
+        pid = productId;
+        serialString = serialNumber;
     }
 
     /**
@@ -64,7 +64,7 @@ public USBDeviceFilter(int vendorId, int productId, String serialNumber) {
      * @return vendor ID, or {@code null} if the vendor ID is not relevant for matching
      */
     public Integer vendorId() {
-        return vendorId_;
+        return vid;
     }
 
     /**
@@ -73,7 +73,7 @@ public Integer vendorId() {
      * @param vendorId vendor ID, or {@code null} if the vendor ID is not relevant for matching
      */
     public void setVendorId(Integer vendorId) {
-        vendorId_ = vendorId;
+        vid = vendorId;
     }
 
     /**
@@ -82,7 +82,7 @@ public void setVendorId(Integer vendorId) {
      * @return product ID, or {@code null} if the product ID is not relevant for matching
      */
     public Integer productId() {
-        return productId_;
+        return pid;
     }
 
     /**
@@ -91,7 +91,7 @@ public Integer productId() {
      * @param productId product ID, or {@code null} if the product ID is not relevant for matching
      */
     public void setProductId(Integer productId) {
-        productId_ = productId;
+        pid = productId;
     }
 
     /**
@@ -100,7 +100,7 @@ public void setProductId(Integer productId) {
      * @return class code, or {@code null} if the class code is not relevant for matching
      */
     public Integer classCode() {
-        return classCode_;
+        return deviceClass;
     }
 
     /**
@@ -109,7 +109,7 @@ public Integer classCode() {
      * @param classCode class code, or {@code null} if the class code is not relevant for matching
      */
     public void setClassCode(Integer classCode) {
-        classCode_ = classCode;
+        deviceClass = classCode;
     }
 
     /**
@@ -118,7 +118,7 @@ public void setClassCode(Integer classCode) {
      * @return subclass code, or {@code null} if the subclass code is not relevant for matching
      */
     public Integer subclassCode() {
-        return subclassCode_;
+        return deviceSubclass;
     }
 
     /**
@@ -127,7 +127,7 @@ public Integer subclassCode() {
      * @param subclassCode subclass code, or {@code null} if the subclass code is not relevant for matching
      */
     public void setSubclassCode(Integer subclassCode) {
-        subclassCode_ = subclassCode;
+        deviceSubclass = subclassCode;
     }
 
     /**
@@ -136,16 +136,16 @@ public void setSubclassCode(Integer subclassCode) {
      * @return protocol code, or {@code null} if the protocol code is not relevant for matching
      */
     public Integer protocolCode() {
-        return protocolCode_;
+        return deviceProtocol;
     }
 
     /**
      * Sets the USB device protocol code.
      *
      * @param protocolCode protocol code, or {@code null} if the protocol code is not relevant for matching
      */
-    public void setProtocolCode_(Integer protocolCode) {
-        protocolCode_ = protocolCode;
+    public void setProtocolCode(Integer protocolCode) {
+        deviceProtocol = protocolCode;
     }
 
     /**
@@ -154,7 +154,7 @@ public void setProtocolCode_(Integer protocolCode) {
      * @return serial number, or {@code null} if the serial number is not relevant for matching
      */
     public String serialNumber() {
-        return serialNumber_;
+        return serialString;
     }
 
     /**
@@ -163,7 +163,7 @@ public String serialNumber() {
      * @param serialNumber serial number, or {@code null} if the serial number is not relevant for matching
      */
     public void setSerialNumber(String serialNumber) {
-        serialNumber_ = serialNumber;
+        serialString = serialNumber;
     }
 
     /**
@@ -173,27 +173,16 @@ public void setSerialNumber(String serialNumber) {
      * @return {@code true} if it matches, {@code false} otherwise
      */
     public boolean matches(USBDevice device) {
-        if (vendorId_ != null && device.vendorId() != vendorId_)
+        if (vid != null && device.vendorId() != vid)
             return false;
-        if (productId_ != null && device.productId() != productId_)
+        if (pid != null && device.productId() != pid)
             return false;
-        if (serialNumber_ != null && !serialNumber_.equals(device.serialNumber()))
+        if (serialString != null && !serialString.equals(device.serialNumber()))
             return false;
-        if (classCode_ != null && device.classCode() != classCode_)
+        if (deviceClass != null && device.classCode() != deviceClass)
             return false;
-        if (subclassCode_ != null && device.subclassCode() != subclassCode_)
+        if (deviceSubclass != null && device.subclassCode() != deviceSubclass)
             return false;
-        return protocolCode_ == null || device.protocolCode() == protocolCode_;
-    }
-
-    /**
-     * Test if the USB devices matches any of the filter conditions.
-     *
-     * @param device  the USB device
-     * @param filters a list of filter conditions
-     * @return {@code true} if it matches, {@code false} otherwise
-     */
-    public static boolean matchesAny(USBDevice device, List<USBDeviceFilter> filters) {
-        return filters.stream().anyMatch(filter -> filter.matches(device));
+        return deviceProtocol == null || device.protocolCode() == deviceProtocol;
     }
 }

java-does-usb/src/main/java/net/codecrete/usb/USBDevicePredicate.java

@@ -0,0 +1,38 @@
+//
+// Java Does USB
+// Copyright (c) 2022 Manuel Bleichenbacher
+// Licensed under MIT License
+// https://opensource.org/licenses/MIT
+//
+
+package net.codecrete.usb;
+
+import java.util.List;
+
+/**
+ * Represents a predicate (boolean-valued function) of one argument, evaluated for a given USB device.
+ * <p>
+ * This is a functional interface whose functional method is {@link #matches(USBDevice)}.
+ * </p>
+ */
+@FunctionalInterface
+public interface USBDevicePredicate {
+    /**
+     * Evaluates this predicate on the given USB device.
+     *
+     * @param device the USB device
+     * @return {@code true} of the devices matches the predicate, otherwise {@code false}
+     */
+    boolean matches(USBDevice device);
+
+    /**
+     * Test if the USB devices matches any of the filter conditions.
+     *
+     * @param device  the USB device
+     * @param predicates a list of filter predicates
+     * @return {@code true} if it matches, {@code false} otherwise
+     */
+    public static boolean matchesAny(USBDevice device, List<USBDevicePredicate> predicates) {
+        return predicates.stream().anyMatch(predicate -> predicate.matches(device));
+    }
+}

java-does-usb/src/main/java/net/codecrete/usb/USBException.java

@@ -15,7 +15,7 @@ public class USBException extends RuntimeException {
     /**
      * Error code.
      */
-    private int errorCode_ = -1;
+    private int code = -1;
 
     /**
      * Creates a new instance with a message.
@@ -34,7 +34,7 @@ public USBException(String message) {
      */
     public USBException(String message, int errorCode) {
         super(message + " (error code: " + errorCode + ")");
-        errorCode_ = errorCode;
+        code = errorCode;
     }
 
     /**
@@ -53,6 +53,6 @@ public USBException(String message, Throwable cause) {
      * @return the error code
      */
     public int errorCode() {
-        return errorCode_;
+        return code;
     }
 }