more convenience for builders

datastructures-api/src/main/java/org/xbib/datastructures/api/Builder.java

@@ -18,11 +18,19 @@ public interface Builder {
 
     Builder buildCollection(Collection<Object> collection) throws IOException;
 
-    Builder buildKey(CharSequence charSequence) throws IOException;
+    Builder buildKey(CharSequence key) throws IOException;
 
-    Builder buildValue(Object object) throws IOException;
+    Builder buildValue(Object value) throws IOException;
 
     Builder buildNull() throws IOException;
 
+    default Builder buildIfNotNull(CharSequence key, Object value) throws IOException {
+        if (value != null){
+            buildKey(key);
+            buildValue(value);
+        }
+        return this;
+    }
+
     String build();
 }

datastructures-json-tiny/src/main/java/org/xbib/datastructures/json/tiny/JsonBuilder.java

@@ -28,6 +28,14 @@ public class JsonBuilder implements Builder {
         this.state = new State(null, 0, Structure.MAP, true);
     }
 
+    public static JsonBuilder builder() {
+        return new JsonBuilder();
+    }
+
+    public static JsonBuilder builder(Writer writer) {
+        return new JsonBuilder(writer);
+    }
+
     @Override
     public Builder beginCollection() throws IOException {
         this.state = new State(state, state.level + 1, Structure.COLLECTION, true);

datastructures-yaml-tiny/src/main/java/org/xbib/datastructures/yaml/tiny/YamlBuilder.java

@@ -3,8 +3,8 @@ package org.xbib.datastructures.yaml.tiny;
 import org.xbib.datastructures.api.Builder;
 import org.xbib.datastructures.api.ByteSizeValue;
 import org.xbib.datastructures.api.TimeValue;
-
 import java.io.IOException;
+import java.io.StringWriter;
 import java.io.UncheckedIOException;
 import java.io.Writer;
 import java.time.Instant;
@@ -20,6 +20,10 @@ public class YamlBuilder implements Builder {
 
     private State state;
 
+    public YamlBuilder() {
+        this(new StringWriter());
+    }
+
     public YamlBuilder(Writer writer) {
         this(writer, 2);
     }
@@ -30,6 +34,14 @@ public class YamlBuilder implements Builder {
         this.state = new State(null, 0, Structure.MAP, false);
     }
 
+    public static YamlBuilder builder() {
+        return new YamlBuilder();
+    }
+
+    public static YamlBuilder builder(Writer writer) {
+        return new YamlBuilder(writer);
+    }
+
     @Override
     public Builder beginCollection() {
         this.state = new State(state, state.level + 1, Structure.COLLECTION, true);