ConstantPatternCompile suggested fix improvements

[Stephan202]

Consider the following code:

import java.util.regex.Pattern;

final class Dummy {
    /**
     * This is my method.
     *
     * @param str This is its parameter.
     */
    public boolean myMethod(String str) {
        Pattern pattern = Pattern.compile(".*");
        return pattern.matcher(str).matches();
    }
}

Applying the ConstantPatternCompile check to this code:

wget \
  https://repo1.maven.org/maven2/com/google/errorprone/error_prone_core/2.4.0/error_prone_core-2.4.0-with-dependencies.jar
javac \
  -XDcompilePolicy=simple \
  -processorpath error_prone_core-2.4.0-with-dependencies.jar \
  '-Xplugin:ErrorProne -XepPatchChecks:ConstantPatternCompile -XepPatchLocation:/tmp' \
  Dummy.java

This yields:

--- Dummy.java
+++ Dummy.java
@@ -7,7 +7,7 @@
      * @param str This is its parameter.
      */
-    public boolean myMethod(String str) {
-        Pattern pattern = Pattern.compile(".*");
-        return pattern.matcher(str).matches();
+    static final Pattern PATTERN = Pattern.compile(".*");public boolean myMethod(String str) {
+        
+        return PATTERN.matcher(str).matches();
     }
 }

As can be seen:

• The new constant isn't declared private, while it should be.
• The new constant is declared between the method and its Javadoc, such that the Javadoc now appears to apply to the constant. (And on a subsequent compilation round InvalidBlockTag will suggest that the @param block tag be removed.)
• Although one will likely want to reformat the code anyway, it'd be nice if a newline were inserted after the semicolon.