fix predicate builder

Author: Doha2012

spring-security-rest-full/src/main/java/org/baeldung/persistence/dao/MyUserPredicatesBuilder.java

@@ -7,28 +7,25 @@
 
 import com.mysema.query.types.expr.BooleanExpression;
 
-public class MyUserPredicatesBuilder {
-    private List<SearchCriteria> params;
+public final class MyUserPredicatesBuilder {
+    private final List<SearchCriteria> params;
 
     public MyUserPredicatesBuilder() {
         params = new ArrayList<SearchCriteria>();
     }
 
     public MyUserPredicatesBuilder with(final String key, final String operation, final Object value) {
-        final MyUserPredicatesBuilder builder = new MyUserPredicatesBuilder();
-        final List<SearchCriteria> newParams = new ArrayList<SearchCriteria>(params);
-        newParams.add(new SearchCriteria(key, operation, value));
-        builder.params = newParams;
-        return builder;
+        params.add(new SearchCriteria(key, operation, value));
+        return this;
     }
 
     public BooleanExpression build() {
-        if (params.size() == 0)
+        if (params.size() == 0) {
             return null;
+        }
 
         final List<BooleanExpression> predicates = new ArrayList<BooleanExpression>();
         MyUserPredicate predicate;
-
         for (final SearchCriteria param : params) {
             predicate = new MyUserPredicate(param);
             final BooleanExpression exp = predicate.getPredicate();
@@ -37,14 +34,10 @@ public BooleanExpression build() {
             }
         }
 
-        if (predicates.size() == 0)
-            return null;
-
         BooleanExpression result = predicates.get(0);
         for (int i = 1; i < predicates.size(); i++) {
             result = result.and(predicates.get(i));
         }
         return result;
-
     }
 }

spring-security-rest-full/src/main/java/org/baeldung/web/controller/UserController.java

@@ -72,20 +72,16 @@ public List<User> findAllBySpecification(@RequestParam(value = "search") final S
     @RequestMapping(method = RequestMethod.GET, value = "/myusers")
     @ResponseBody
     public Iterable<MyUser> findAllByQuerydsl(@RequestParam(value = "search") final String search) {
-        MyUserPredicatesBuilder builder = new MyUserPredicatesBuilder();
-
+        final MyUserPredicatesBuilder builder = new MyUserPredicatesBuilder();
         if (search != null) {
             final Pattern pattern = Pattern.compile("(\\w+?)(:|<|>)(\\w+?),");
             final Matcher matcher = pattern.matcher(search + ",");
             while (matcher.find()) {
-                builder = builder.with(matcher.group(1), matcher.group(2), matcher.group(3));
+                builder.with(matcher.group(1), matcher.group(2), matcher.group(3));
             }
         }
         final BooleanExpression exp = builder.build();
-        if (exp == null)
-            return mydao.findAll();
-        else
-            return mydao.findAll(exp);
+        return mydao.findAll(exp);
     }
 
     // API - WRITE