Add option to treat empty strings as null values

README.md

@@ -172,6 +172,19 @@ for (DotenvEntry e : dotenv.entries()) {
 	  .load();
 	```
 
+### *optional* `ignoreEmpty`
+
+* Treat empty or blank values as `null`.
+
+  **example**
+
+  ```java
+  Dotenv
+    .configure()
+    .ignoreEmpty()
+    .load();
+  ```
+
 ### *optional* `systemProperties` 
 
 * Load environment variables into System properties, thus making all environment variables accessible via `System.getProperty(...)`

src/main/java/io/github/cdimascio/dotenv/DotenvBuilder.java

@@ -15,6 +15,7 @@ public class DotenvBuilder {
     private String filename = ".env";
     private String directoryPath = "./";
     private boolean systemProperties = false;
+    private boolean ignoreEmpty = false;
     private boolean throwIfMissing = true;
     private boolean throwIfMalformed = true;
 
@@ -37,6 +38,15 @@ public DotenvBuilder filename(String name) {
         return this;
     }
 
+    /**
+     * Returns `null` for empty or blank values.
+     * @return this {@link DotenvBuilder}
+     */
+    public DotenvBuilder ignoreEmpty() {
+        ignoreEmpty = true;
+        return this;
+    }
+
     /**
      * Does not throw an exception when .env is missing.
      * @return this {@link DotenvBuilder}
@@ -72,6 +82,7 @@ public DotenvBuilder systemProperties() {
     public Dotenv load() throws DotenvException {
         DotenvParser reader = new DotenvParser(
             new DotenvReader(directoryPath, filename),
+            ignoreEmpty,
             throwIfMissing,
             throwIfMalformed);
         List<DotenvEntry> env = reader.parse();

src/main/java/io/github/cdimascio/dotenv/internal/DotenvParser.java

@@ -17,6 +17,7 @@
  */
 public class DotenvParser {
     private final DotenvReader reader;
+    private final boolean ignoreEmtpy;
     private final boolean throwIfMissing;
     private final boolean throwIfMalformed;
 
@@ -28,11 +29,13 @@ public class DotenvParser {
     /**
      * Creates a dotenv parser
      * @param reader the dotenv reader
+     * @param ignoreEmpty if true, returns `null` for empty or blank values
      * @param throwIfMissing if true, throws when the .env file is missing
      * @param throwIfMalformed if true, throws when the .env file is malformed
      */
-    public DotenvParser(DotenvReader reader, boolean throwIfMissing, boolean throwIfMalformed) {
+    public DotenvParser(DotenvReader reader, boolean ignoreEmpty, boolean throwIfMissing, boolean throwIfMalformed) {
         this.reader = reader;
+        this.ignoreEmtpy = ignoreEmpty;
         this.throwIfMissing = throwIfMissing;
         this.throwIfMalformed = throwIfMalformed;
     }
@@ -55,6 +58,9 @@ public List<DotenvEntry> parse() throws DotenvException {
             }
             String key = entry.getKey();
             String value = normalizeValue(entry.getValue());
+            if (value.isEmpty() && ignoreEmtpy) {
+                continue;
+            }
             entries.add(new DotenvEntry(key, value));
         }
         return entries;

src/test/java/tests/DotenvTests.java

@@ -13,6 +13,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 public class DotenvTests {
@@ -114,4 +115,14 @@ public void configureWithIgnoreMissingAndMalformed() {
 
         assertNotNull(dotenv.get("PATH"));
     }
+
+    @Test
+    public void configureWithIgnoreMalformedAndEmpty() {
+        Dotenv dotenv = Dotenv.configure()
+            .ignoreIfMalformed()
+            .ignoreEmpty()
+            .load();
+
+        assertNull(dotenv.get("WITHOUT_VALUE"));
+    }
 }