diff --git a/src/main/java/xyz/zhouxy/plusone/commons/base/BoolRef.java b/src/main/java/xyz/zhouxy/plusone/commons/base/BoolRef.java
index 56918ad..0527d74 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/base/BoolRef.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/base/BoolRef.java
@@ -18,6 +18,7 @@ package xyz.zhouxy.plusone.commons.base;
 
 import com.google.common.annotations.Beta;
 
+import xyz.zhouxy.plusone.commons.annotation.StaticFactoryMethod;
 import xyz.zhouxy.plusone.commons.function.BoolUnaryOperator;
 
 @Beta
@@ -29,6 +30,11 @@ public class BoolRef {
         this.value = value;
     }
 
+    @StaticFactoryMethod(BoolRef.class)
+    public static BoolRef of(boolean value) {
+        return new BoolRef(value);
+    }
+
     public boolean getValue() {
         return value;
     }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/base/CharRef.java b/src/main/java/xyz/zhouxy/plusone/commons/base/CharRef.java
index 929d4b4..35d409c 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/base/CharRef.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/base/CharRef.java
@@ -18,6 +18,7 @@ package xyz.zhouxy.plusone.commons.base;
 
 import com.google.common.annotations.Beta;
 
+import xyz.zhouxy.plusone.commons.annotation.StaticFactoryMethod;
 import xyz.zhouxy.plusone.commons.function.CharUnaryOperator;
 
 @Beta
@@ -29,6 +30,11 @@ public class CharRef {
         this.value = value;
     }
 
+    @StaticFactoryMethod(CharRef.class)
+    public static CharRef of(char value) {
+        return new CharRef(value);
+    }
+
     public char getValue() {
         return value;
     }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/base/DoubleRef.java b/src/main/java/xyz/zhouxy/plusone/commons/base/DoubleRef.java
index 9c476e5..addecb7 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/base/DoubleRef.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/base/DoubleRef.java
@@ -20,6 +20,8 @@ import java.util.function.DoubleUnaryOperator;
 
 import com.google.common.annotations.Beta;
 
+import xyz.zhouxy.plusone.commons.annotation.StaticFactoryMethod;
+
 @Beta
 public class DoubleRef {
 
@@ -29,6 +31,11 @@ public class DoubleRef {
         this.value = value;
     }
 
+    @StaticFactoryMethod(DoubleRef.class)
+    public static DoubleRef of(double value) {
+        return new DoubleRef(value);
+    }
+
     public double getValue() {
         return value;
     }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/base/IntRef.java b/src/main/java/xyz/zhouxy/plusone/commons/base/IntRef.java
index 8f0148b..32b9b2b 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/base/IntRef.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/base/IntRef.java
@@ -20,6 +20,8 @@ import java.util.function.IntUnaryOperator;
 
 import com.google.common.annotations.Beta;
 
+import xyz.zhouxy.plusone.commons.annotation.StaticFactoryMethod;
+
 @Beta
 public class IntRef {
 
@@ -29,6 +31,11 @@ public class IntRef {
         this.value = value;
     }
 
+    @StaticFactoryMethod(IntRef.class)
+    public static IntRef of(int value) {
+        return new IntRef(value);
+    }
+
     public int getValue() {
         return value;
     }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/base/LongRef.java b/src/main/java/xyz/zhouxy/plusone/commons/base/LongRef.java
index 7d079bd..4f4dd48 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/base/LongRef.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/base/LongRef.java
@@ -20,6 +20,8 @@ import java.util.function.LongUnaryOperator;
 
 import com.google.common.annotations.Beta;
 
+import xyz.zhouxy.plusone.commons.annotation.StaticFactoryMethod;
+
 @Beta
 public class LongRef {
 
@@ -29,6 +31,11 @@ public class LongRef {
         this.value = value;
     }
 
+    @StaticFactoryMethod(LongRef.class)
+    public static LongRef of(long value) {
+        return new LongRef(value);
+    }
+
     public long getValue() {
         return value;
     }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/base/Ref.java b/src/main/java/xyz/zhouxy/plusone/commons/base/Ref.java
index 94c5ee4..28f6067 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/base/Ref.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/base/Ref.java
@@ -22,6 +22,8 @@ import java.util.function.UnaryOperator;
 
 import com.google.common.annotations.Beta;
 
+import xyz.zhouxy.plusone.commons.annotation.StaticFactoryMethod;
+
 @Beta
 public final class Ref<T> {
 
@@ -35,6 +37,16 @@ public final class Ref<T> {
         this.value = value;
     }
 
+    @StaticFactoryMethod(Ref.class)
+    public static <T> Ref<T> of() {
+        return new Ref<>();
+    }
+
+    @StaticFactoryMethod(Ref.class)
+    public static <T> Ref<T> of(T value) {
+        return new Ref<>(value);
+    }
+
     public T getValue() {
         return value;
     }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/function/BoolUnaryOperator.java b/src/main/java/xyz/zhouxy/plusone/commons/function/BoolUnaryOperator.java
index eccef15..9da47a8 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/function/BoolUnaryOperator.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/function/BoolUnaryOperator.java
@@ -21,9 +21,11 @@ import com.google.common.annotations.Beta;
 @Beta
 @FunctionalInterface
 public interface BoolUnaryOperator {
+
     boolean applyAsBool(boolean operand);
 
     static BoolUnaryOperator not() {
         return b -> !b;
     }
+
 }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/function/CharUnaryOperator.java b/src/main/java/xyz/zhouxy/plusone/commons/function/CharUnaryOperator.java
index e9ca630..98bedcf 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/function/CharUnaryOperator.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/function/CharUnaryOperator.java
@@ -21,5 +21,7 @@ import com.google.common.annotations.Beta;
 @Beta
 @FunctionalInterface
 public interface CharUnaryOperator {
+
     char applyAsChar(char operand);
+
 }