修改、新增方法

src/main/java/xyz/zhouxy/plusone/commons/base/Ref.java

@@ -1,6 +1,7 @@
 package xyz.zhouxy.plusone.commons.base;
 
 import java.util.Objects;
+import java.util.function.Consumer;
 import java.util.function.UnaryOperator;
 
 import com.google.common.annotations.Beta;
@@ -10,6 +11,10 @@ public final class Ref<T> {
 
     private T value;
 
+    public Ref() {
+        this.value = null;
+    }
+
     public Ref(T value) {
         this.value = value;
     }
@@ -22,10 +27,22 @@ public final class Ref<T> {
         this.value = value;
     }
 
-    public void apply(UnaryOperator<T> operator) {
+    public void transform(UnaryOperator<T> operator) {
         this.value = operator.apply(this.value);
     }
 
+    public boolean isNull() {
+        return this.value == null;
+    }
+
+    public boolean isNotNull() {
+        return this.value != null;
+    }
+
+    public void execute(Consumer<T> consumer) {
+        consumer.accept(value);
+    }
+
     @Override
     public String toString() {
         return String.format("Ref[%s]", value);

src/test/java/xyz/zhouxy/plusone/commons/util/RefTests.java

@@ -24,7 +24,7 @@ class RefTests {
     }
 
     void apply(Ref<String> strRef) {
-        strRef.apply(str -> "Hello " + str);
+        strRef.transform(str -> "Hello " + str);
     }
 
     @Test