8258422: Cleanup unnecessary null comparison before instanceof check in java.base

take advantage of "flow scoping" to eliminate casts

Author: turbanoff

src/java.base/share/classes/java/net/AbstractPlainDatagramSocketImpl.java

@@ -235,9 +235,9 @@ protected void leave(InetAddress inetaddr) throws IOException {
 
     protected void joinGroup(SocketAddress mcastaddr, NetworkInterface netIf)
         throws IOException {
-        if (!(mcastaddr instanceof InetSocketAddress))
+        if (!(mcastaddr instanceof InetSocketAddress addr))
             throw new IllegalArgumentException("Unsupported address type");
-        join(((InetSocketAddress)mcastaddr).getAddress(), netIf);
+        join(addr.getAddress(), netIf);
     }
 
     protected abstract void join(InetAddress inetaddr, NetworkInterface netIf)
@@ -253,9 +253,9 @@ protected abstract void join(InetAddress inetaddr, NetworkInterface netIf)
      */
     protected void leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf)
         throws IOException {
-        if (!(mcastaddr instanceof InetSocketAddress))
+        if (!(mcastaddr instanceof InetSocketAddress addr))
             throw new IllegalArgumentException("Unsupported address type");
-        leave(((InetSocketAddress)mcastaddr).getAddress(), netIf);
+        leave(addr.getAddress(), netIf);
     }
 
     protected abstract void leave(InetAddress inetaddr, NetworkInterface netIf)

src/java.base/share/classes/java/net/AbstractPlainSocketImpl.java

@@ -213,9 +213,8 @@ protected void connect(SocketAddress address, int timeout)
             throws IOException {
         boolean connected = false;
         try {
-            if (!(address instanceof InetSocketAddress))
+            if (!(address instanceof InetSocketAddress addr))
                 throw new IllegalArgumentException("unsupported address type");
-            InetSocketAddress addr = (InetSocketAddress) address;
             if (addr.isUnresolved())
                 throw new UnknownHostException(addr.getHostName());
             // recording this.address as supplied by caller before calling connect

src/java.base/share/classes/java/net/DatagramPacket.java

@@ -352,9 +352,8 @@ public synchronized void setPort(int iport) {
      * @since   1.4
      */
     public synchronized void setSocketAddress(SocketAddress address) {
-        if (!(address instanceof InetSocketAddress))
+        if (!(address instanceof InetSocketAddress addr))
             throw new IllegalArgumentException("unsupported address type");
-        InetSocketAddress addr = (InetSocketAddress) address;
         if (addr.isUnresolved())
             throw new IllegalArgumentException("unresolved address");
         setAddress(addr.getAddress());

src/java.base/share/classes/java/net/HttpConnectSocketImpl.java

@@ -102,9 +102,8 @@ protected void connect(InetAddress address, int port) throws IOException {
     protected void connect(SocketAddress endpoint, int timeout)
         throws IOException
     {
-        if (!(endpoint instanceof InetSocketAddress))
+        if (!(endpoint instanceof InetSocketAddress epoint))
             throw new IllegalArgumentException("Unsupported address type");
-        final InetSocketAddress epoint = (InetSocketAddress)endpoint;
         String destHost = epoint.isUnresolved() ? epoint.getHostName()
                                                 : epoint.getAddress().getHostAddress();
         final int destPort = epoint.getPort();

src/java.base/share/classes/java/net/Inet6Address.java

@@ -878,12 +878,10 @@ public int hashCode() {
      */
     @Override
     public boolean equals(Object obj) {
-        if (!(obj instanceof Inet6Address))
-            return false;
-
-        Inet6Address inetAddr = (Inet6Address)obj;
-
-        return holder6.equals(inetAddr.holder6);
+        if (obj instanceof Inet6Address inetAddr) {
+            return holder6.equals(inetAddr.holder6);
+        }
+        return false;
     }
 
     /**

src/java.base/share/classes/java/net/InetSocketAddress.java

@@ -119,9 +119,8 @@ public String toString() {
 
         @Override
         public final boolean equals(Object obj) {
-            if (!(obj instanceof InetSocketAddressHolder))
+            if (!(obj instanceof InetSocketAddressHolder that))
                 return false;
-            InetSocketAddressHolder that = (InetSocketAddressHolder)obj;
             boolean sameIP;
             if (addr != null)
                 sameIP = addr.equals(that.addr);
@@ -409,9 +408,10 @@ public String toString() {
      */
     @Override
     public final boolean equals(Object obj) {
-        if (!(obj instanceof InetSocketAddress))
-            return false;
-        return holder.equals(((InetSocketAddress) obj).holder);
+        if (obj instanceof InetSocketAddress addr) {
+            return holder.equals(addr.holder);
+        }
+        return false;
     }
 
     /**

src/java.base/share/classes/java/net/NetMulticastSocket.java

@@ -801,19 +801,19 @@ public void joinGroup(SocketAddress mcastaddr, NetworkInterface netIf)
         if (isClosed())
             throw new SocketException("Socket is closed");
 
-        if (!(mcastaddr instanceof InetSocketAddress))
+        if (!(mcastaddr instanceof InetSocketAddress addr))
             throw new IllegalArgumentException("Unsupported address type");
 
         if (oldImpl)
             throw new UnsupportedOperationException();
 
-        checkAddress(((InetSocketAddress)mcastaddr).getAddress(), "joinGroup");
+        checkAddress(addr.getAddress(), "joinGroup");
         SecurityManager security = System.getSecurityManager();
         if (security != null) {
-            security.checkMulticast(((InetSocketAddress)mcastaddr).getAddress());
+            security.checkMulticast(addr.getAddress());
         }
 
-        if (!((InetSocketAddress)mcastaddr).getAddress().isMulticastAddress()) {
+        if (!addr.getAddress().isMulticastAddress()) {
             throw new SocketException("Not a multicast address");
         }
 
@@ -826,19 +826,19 @@ public void leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf)
         if (isClosed())
             throw new SocketException("Socket is closed");
 
-        if (!(mcastaddr instanceof InetSocketAddress))
+        if (!(mcastaddr instanceof InetSocketAddress addr))
             throw new IllegalArgumentException("Unsupported address type");
 
         if (oldImpl)
             throw new UnsupportedOperationException();
 
-        checkAddress(((InetSocketAddress)mcastaddr).getAddress(), "leaveGroup");
+        checkAddress(addr.getAddress(), "leaveGroup");
         SecurityManager security = System.getSecurityManager();
         if (security != null) {
-            security.checkMulticast(((InetSocketAddress)mcastaddr).getAddress());
+            security.checkMulticast(addr.getAddress());
         }
 
-        if (!((InetSocketAddress)mcastaddr).getAddress().isMulticastAddress()) {
+        if (!addr.getAddress().isMulticastAddress()) {
             throw new SocketException("Not a multicast address");
         }
 

src/java.base/share/classes/java/net/Proxy.java

@@ -146,9 +146,8 @@ public String toString() {
      * @see java.net.InetSocketAddress#equals(java.lang.Object)
      */
     public final boolean equals(Object obj) {
-        if (!(obj instanceof Proxy))
+        if (!(obj instanceof Proxy p))
             return false;
-        Proxy p = (Proxy) obj;
         if (p.type() == type()) {
             if (address() == null) {
                 return (p.address() == null);

src/java.base/share/classes/java/net/SocksSocketImpl.java

@@ -272,9 +272,8 @@ protected void connect(SocketAddress endpoint, int timeout) throws IOException {
         }
 
         SecurityManager security = System.getSecurityManager();
-        if (!(endpoint instanceof InetSocketAddress))
+        if (!(endpoint instanceof InetSocketAddress epoint))
             throw new IllegalArgumentException("Unsupported address type");
-        InetSocketAddress epoint = (InetSocketAddress) endpoint;
         if (security != null) {
             if (epoint.isUnresolved())
                 security.checkConnect(epoint.getHostName(),

src/java.base/share/classes/java/nio/file/attribute/AclEntry.java

@@ -342,9 +342,8 @@ public Set<AclEntryFlag> flags() {
     public boolean equals(Object ob) {
         if (ob == this)
             return true;
-        if (!(ob instanceof AclEntry))
+        if (!(ob instanceof AclEntry other))
             return false;
-        AclEntry other = (AclEntry)ob;
         if (this.type != other.type)
             return false;
         if (!this.who.equals(other.who))