diff --git a/src/main/java/xyz/zhouxy/plusone/commons/math/Interval.java b/src/main/java/xyz/zhouxy/plusone/commons/math/Interval.java
new file mode 100644
index 0000000..e454fb1
--- /dev/null
+++ b/src/main/java/xyz/zhouxy/plusone/commons/math/Interval.java
@@ -0,0 +1,62 @@
+package xyz.zhouxy.plusone.commons.math;
+
+import java.util.Optional;
+
+import javax.annotation.Nonnull;
+
+import com.google.common.base.Preconditions;
+
+import xyz.zhouxy.plusone.commons.util.Numbers;
+
+public class Interval<T extends Comparable<T>> {
+    @Nonnull
+    private final IntervalType intervalType;
+    private final T lowerBound;
+    private final T upperBound;
+
+    public Interval(@Nonnull IntervalType intervalType, T lowerBound, T upperBound) {
+        Preconditions.checkNotNull(intervalType);
+        if (intervalType.isLeftClosed()) {
+            Preconditions.checkArgument(lowerBound != null,
+                    "The lower bound cannot be null, when the interval is left-closed.");
+        }
+        if (intervalType.isRightClosed()) {
+            Preconditions.checkArgument(upperBound != null,
+                    "The upper bound cannot be null, when the interval is right-closed.");
+        }
+        if (lowerBound != null && upperBound != null) {
+            Preconditions.checkArgument(lowerBound.compareTo(upperBound) <= 0,
+                    "The lower bound must less than the upper bound.");
+        }
+        this.intervalType = intervalType;
+        this.lowerBound = lowerBound;
+        this.upperBound = upperBound;
+    }
+
+    @Nonnull
+    public IntervalType getIntervalType() {
+        return intervalType;
+    }
+
+    @Nonnull
+    public Optional<T> getLowerBound() {
+        return Optional.ofNullable(lowerBound);
+    }
+
+    @Nonnull
+    public Optional<T> getUpperBound() {
+        return Optional.ofNullable(upperBound);
+    }
+
+    public boolean isLeftClosed() {
+        return this.intervalType.isLeftClosed();
+    }
+
+    public boolean isRightClosed() {
+        return this.intervalType.isRightClosed();
+    }
+
+    public boolean validValue(@Nonnull T value) {
+        return Numbers.between(value, this.lowerBound, this.upperBound, this.intervalType);
+    }
+}
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/math/IntervalType.java b/src/main/java/xyz/zhouxy/plusone/commons/math/IntervalType.java
new file mode 100644
index 0000000..e32a3fe
--- /dev/null
+++ b/src/main/java/xyz/zhouxy/plusone/commons/math/IntervalType.java
@@ -0,0 +1,32 @@
+package xyz.zhouxy.plusone.commons.math;
+
+public enum IntervalType {
+    /** 开区间。(a,b)={x|a < x < b} */
+    OPEN(false, false),
+    /** 闭区间。[a,b]={x|a ≤ x ≤ b} */
+    CLOSED(true, true),
+    /** 左闭右开区间。[a,b)={x|a ≤ x < b} */
+    CLOSED_OPEN(true, false),
+    /** 左开右闭区间。(a,b]={x|a < x ≤ b} */
+    OPEN_CLOSED(false, true);
+
+    private final boolean leftClosed;
+    private final boolean rightClosed;
+
+    IntervalType(boolean leftClosed, boolean rightClosed) {
+        this.leftClosed = leftClosed;
+        this.rightClosed = rightClosed;
+    }
+
+    public final boolean isLeftClosed() {
+        return leftClosed;
+    }
+
+    public final boolean isRightClosed() {
+        return rightClosed;
+    }
+
+    public final <T extends Comparable<T>> Interval<T> buildInterval(T left, T right) {
+        return new Interval<>(this, left, right);
+    }
+}
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/Numbers.java b/src/main/java/xyz/zhouxy/plusone/commons/util/Numbers.java
index 3c499f0..cd66aa0 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/Numbers.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/Numbers.java
@@ -18,6 +18,12 @@ package xyz.zhouxy.plusone.commons.util;
 
 import java.math.BigDecimal;
 
+import javax.annotation.Nonnull;
+
+import com.google.common.base.Preconditions;
+
+import xyz.zhouxy.plusone.commons.math.IntervalType;
+
 /**
  * Numbers
  *
@@ -77,28 +83,93 @@ public class Numbers {
 
     // between
 
-    public static boolean between(short value, short min, short max) {
-        return value >= min && value < max;
+    public static boolean between(int value, int min, int max) {
+        return between(value, min, max, IntervalType.CLOSED_OPEN);
     }
 
-    public static boolean between(int value, int min, int max) {
-        return value >= min && value < max;
+    public static boolean between(int value, int min, int max, IntervalType intervalType) {
+        final IntervalType intervalTypeToUse = intervalType != null
+                ? intervalType
+                : IntervalType.CLOSED_OPEN;
+        switch (intervalTypeToUse) {
+            case OPEN:
+                return min < value && value < max;
+            case CLOSED:
+                return min <= value && value <= max;
+            case OPEN_CLOSED:
+                return min < value && value <= max;
+            case CLOSED_OPEN:
+            default:
+                return min <= value && value < max;
+        }
     }
 
     public static boolean between(long value, long min, long max) {
-        return value >= min && value < max;
+        return between(value, min, max, IntervalType.CLOSED_OPEN);
     }
 
-    public static boolean between(float value, float min, float max) {
-        return value >= min && value < max;
+    public static boolean between(long value, long min, long max, IntervalType intervalType) {
+        final IntervalType intervalTypeToUse = intervalType != null
+                ? intervalType
+                : IntervalType.CLOSED_OPEN;
+        switch (intervalTypeToUse) {
+            case OPEN:
+                return min < value && value < max;
+            case CLOSED:
+                return min <= value && value <= max;
+            case OPEN_CLOSED:
+                return min < value && value <= max;
+            case CLOSED_OPEN:
+            default:
+                return min <= value && value < max;
+        }
     }
 
     public static boolean between(double value, double min, double max) {
-        return value >= min && value < max;
+        return between(value, min, max, IntervalType.CLOSED_OPEN);
     }
 
-    public static boolean between(BigDecimal value, BigDecimal min, BigDecimal max) {
-        return BigDecimals.ge(value, min) && BigDecimals.lt(value, max);
+    public static boolean between(double value, double min, double max, IntervalType intervalType) {
+        final IntervalType intervalTypeToUse = intervalType != null
+                ? intervalType
+                : IntervalType.CLOSED_OPEN;
+        switch (intervalTypeToUse) {
+            case OPEN:
+                return min < value && value < max;
+            case CLOSED:
+                return min <= value && value <= max;
+            case OPEN_CLOSED:
+                return min < value && value <= max;
+            case CLOSED_OPEN:
+            default:
+                return min <= value && value < max;
+        }
+    }
+
+    public static <T extends Comparable<T>> boolean between(@Nonnull T value, T min, T max) {
+        return between(value, min, max, IntervalType.CLOSED_OPEN);
+    }
+
+    public static <T extends Comparable<T>> boolean between(@Nonnull T value, T min, T max, IntervalType intervalType) {
+        Preconditions.checkArgument(value != null, "The value to valid connot be null.");
+        IntervalType intervalTypeToUse = intervalType != null
+                ? intervalType
+                : IntervalType.CLOSED_OPEN;
+        switch (intervalTypeToUse) {
+            case OPEN:
+                return (min == null || min.compareTo(value) < 0)
+                        && (max == null || value.compareTo(max) < 0);
+            case CLOSED:
+                return (min == null || min.compareTo(value) <= 0)
+                        && (max == null || value.compareTo(max) <= 0);
+            case OPEN_CLOSED:
+                return (min == null || min.compareTo(value) < 0)
+                        && (max == null || value.compareTo(max) <= 0);
+            case CLOSED_OPEN:
+            default:
+                return (min == null || min.compareTo(value) <= 0)
+                        && (max == null || value.compareTo(max) < 0);
+        }
     }
 
     private Numbers() {