feat(jdbc): Clean up logic warnings (#7617)

Author: PerfectSlayer

dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/instrumentation/jdbc/JDBCConnectionUrlParser.java

@@ -1,6 +1,7 @@
 package datadog.trace.bootstrap.instrumentation.jdbc;
 
 import static datadog.trace.bootstrap.instrumentation.jdbc.DBInfo.DEFAULT;
+import static java.lang.Math.max;
 
 import datadog.trace.api.Pair;
 import datadog.trace.api.cache.DDCache;
@@ -201,7 +202,7 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
         hostEndLoc = portLoc;
         try {
           builder.port(Integer.parseInt(jdbcUrl.substring(portLoc + 1, dbLoc)));
-        } catch (final NumberFormatException e) {
+        } catch (final NumberFormatException ignored) {
         }
       } else {
         hostEndLoc = dbLoc;
@@ -224,10 +225,11 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
       }
       final int hostEndLoc;
       final int clusterSepLoc = jdbcUrl.indexOf(',');
-      final int ipv6End = jdbcUrl.startsWith("[") ? jdbcUrl.indexOf(']') : -1;
-      int portLoc = jdbcUrl.indexOf(':', Math.max(0, ipv6End));
-      portLoc = clusterSepLoc < portLoc ? -1 : portLoc;
-      final int dbLoc = jdbcUrl.indexOf('/', Math.max(portLoc, clusterSepLoc));
+      final int ipv6End =
+          !jdbcUrl.isEmpty() && jdbcUrl.charAt(0) == '[' ? jdbcUrl.indexOf(']') : -1;
+      int portLoc = jdbcUrl.indexOf(':', max(0, ipv6End));
+      portLoc = -1 < clusterSepLoc && clusterSepLoc < portLoc ? -1 : portLoc;
+      final int dbLoc = jdbcUrl.indexOf('/', max(portLoc, clusterSepLoc));
 
       final int paramLoc = jdbcUrl.indexOf('?', dbLoc);
 
@@ -247,7 +249,7 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
         final int portEndLoc = clusterSepLoc > 0 ? clusterSepLoc : dbLoc;
         try {
           builder.port(Integer.parseInt(jdbcUrl.substring(portLoc + 1, portEndLoc)));
-        } catch (final NumberFormatException e) {
+        } catch (final NumberFormatException ignored) {
         }
       } else {
         hostEndLoc = clusterSepLoc > 0 ? clusterSepLoc : dbLoc;
@@ -390,7 +392,7 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
             Integer parsedPort = null;
             try {
               parsedPort = Integer.parseInt(portOrInstance);
-            } catch (final NumberFormatException e) {
+            } catch (final NumberFormatException ignored) {
             }
             if (parsedPort == null) {
               port = null;
@@ -566,7 +568,7 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
 
     @Override
     DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
-      String instance = null;
+      String instance;
       final DBInfo dbInfo = builder.build();
       if (dbInfo.getUser() == null) {
         builder.user(DEFAULT_USER);
@@ -680,9 +682,8 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
         }
       } else {
         builder.subtype("directory");
-        final String urlInstance = details;
-        if (!urlInstance.isEmpty()) {
-          instance = urlInstance;
+        if (!details.isEmpty()) {
+          instance = details;
         }
       }
 
@@ -695,7 +696,6 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
 
   /** http://jtds.sourceforge.net/faq.html#urlFormat */
   JTDS("jtds") {
-    private static final String DEFAULT_HOST = "localhost";
     private static final int DEFAULT_SQL_SERVER_PORT = 1433;
     private static final int DEFAULT_SYBASE_PORT = 7100;
 
@@ -741,7 +741,7 @@ DBInfo.Builder doParse(final String jdbcUrl, final DBInfo.Builder builder) {
         hostEndLoc = portLoc;
         try {
           builder.port(Integer.parseInt(details.substring(portLoc + 1, dbLoc)));
-        } catch (final NumberFormatException e) {
+        } catch (final NumberFormatException ignored) {
         }
       } else if (dbLoc > 0) {
         hostEndLoc = dbLoc;