test/tools/javac/diags/MessageFile.java

@@ -63,11 +63,10 @@
             insertAfter(l);
             return l;
         }
 
         void insertAfter(Line l) {
-            assert prev == null && next == null;
             l.prev = this;
             l.next = next;
             if (next == null)
                 lastLine = l;
             else

@@ -80,11 +79,10 @@
             insertBefore(l);
             return l;
         }
 
         void insertBefore(Line l) {
-            assert prev == null && next == null;
             l.prev = prev;
             l.next = this;
             if (prev == null)
                 firstLine = l;
             else

@@ -408,15 +406,12 @@
     Line firstLine;
     Line lastLine;
     Map<String, Message> messages = new TreeMap<String, Message>();
 
     MessageFile(File file) throws IOException {
-        Reader in = new FileReader(file);
-        try {
+        try(Reader in = new FileReader(file)) {
             read(in);
-        } finally {
-            in.close();
         }
     }
 
     MessageFile(Reader in) throws IOException {
         read(in);

@@ -440,15 +435,12 @@
             }
         }
     }
 
     void write(File file) throws IOException {
-        Writer out = new FileWriter(file);
-        try {
+        try(Writer out = new FileWriter(file)) {
             write(out);
-        } finally {
-            out.close();
         }
     }
 
     void write(Writer out) throws IOException {
         BufferedWriter bw = (out instanceof BufferedWriter)