Package com.google.common.base

Class Objects

java.lang.Object
com.google.common.base.Objects
@GwtCompatible public final class Objects extends Object
Helper functions that can operate on any Object.

See the Guava User Guide on writing Object methods with Objects.

Since:
2.0

  • Method Details

    • equal

      public static boolean equal(@Nullable Object a, @Nullable Object b)
      Determines whether two possibly-null objects are equal. Returns:
      • true if a and b are both null.
      • true if a and b are both non-null and they are equal according to Object.equals(Object).
      • false in all other situations.

      This assumes that any non-null objects passed to this function conform to the equals() contract.

      Note for Java 7 and later: This method should be treated as deprecated; use Objects.equals(java.lang.Object, java.lang.Object) instead.

    • hashCode

      public static int hashCode(@Nullable Object... objects)
      Generates a hash code for multiple values. The hash code is generated by calling Arrays.hashCode(Object[]). Note that array arguments to this method, with the exception of a single Object array, do not get any special handling; their hash codes are based on identity and not contents.

      This is useful for implementing Object.hashCode(). For example, in an object that has three properties, x, y, and z, one could write: 

         
   public int hashCode() {
     return Objects.hashCode(getX(), getY(), getZ());
   }

      Warning: When a single object is supplied, the returned hash code does not equal the hash code of that object.

      Note for Java 7 and later: This method should be treated as deprecated; use Objects.hash(java.lang.Object...) instead.

    • toStringHelper

      @Deprecated public static Objects.ToStringHelper toStringHelper(Object self)
      Deprecated.
      Use MoreObjects.toStringHelper(Object) instead. This method is scheduled for removal in Guava 21.0.
      Creates an instance of Objects.ToStringHelper.

      This is helpful for implementing Object.toString(). Specification by example: 

         
   // Returns "ClassName{}"
   Objects.toStringHelper(this)
       .toString();

   // Returns "ClassName{x=1}"
   Objects.toStringHelper(this)
       .add("x", 1)
       .toString();

   // Returns "MyObject{x=1}"
   Objects.toStringHelper("MyObject")
       .add("x", 1)
       .toString();

   // Returns "ClassName{x=1, y=foo}"
   Objects.toStringHelper(this)
       .add("x", 1)
       .add("y", "foo")
       .toString();

   // Returns "ClassName{x=1}"
   Objects.toStringHelper(this)
       .omitNullValues()
       .add("x", 1)
       .add("y", null)
       .toString();
   }

      Note that in GWT, class names are often obfuscated.

      Parameters:
      self - the object to generate the string for (typically this), used only for its class name
      Since:
      2.0

    • toStringHelper

      @Deprecated public static Objects.ToStringHelper toStringHelper(Class<?> clazz)
      Deprecated.
      Use MoreObjects.toStringHelper(Class) instead. This method is scheduled for removal in Guava 21.0.
      Creates an instance of Objects.ToStringHelper in the same manner as toStringHelper(Object), but using the name of clazz instead of using an instance's Object.getClass().

      Note that in GWT, class names are often obfuscated.

      Parameters:
      clazz - the Class of the instance
      Since:
      7.0 (source-compatible since 2.0)

    • toStringHelper

      @Deprecated public static Objects.ToStringHelper toStringHelper(String className)
      Deprecated.
      Use MoreObjects.toStringHelper(String) instead. This method is scheduled for removal in Guava 21.0.
      Creates an instance of Objects.ToStringHelper in the same manner as toStringHelper(Object), but using className instead of using an instance's Object.getClass().
      Parameters:
      className - the name of the instance type
      Since:
      7.0 (source-compatible since 2.0)

    • firstNonNull

      @Deprecated public static <T> T firstNonNull(@Nullable T first, @Nullable T second)
      Deprecated.
      Use MoreObjects.firstNonNull(T, T) instead. This method is scheduled for removal in Guava 21.0.
      Returns the first of two given parameters that is not null, if either is, or otherwise throws a NullPointerException.

      Note: if first is represented as an Optional, this can be accomplished with first.or(second). That approach also allows for lazy evaluation of the fallback instance, using first.or(Supplier).

      Returns:
      first if first is not null, or second if first is null and second is not null
      Throws:
      NullPointerException - if both first and second were null
      Since:
      3.0