How do you make two objects equal in Java?
Java determines equality with the equals(Object o) method – two objects a and b are equal iff a. equals(b) and b. equals(a) return true . These two objects will be equal using the base Object definition of equality, so you don’t have to worry about that.
What is difference between == equals () and compareTo () method?
equals() checks if two objects are the same or not and returns a boolean. compareTo() (from interface Comparable) returns an integer. It checks which of the two objects is “less than”, “equal to” or “greater than” the other. … Note that equals() doesn’t define the ordering between objects, which compareTo() does.
How could you check if two strings are equal?
You can check the equality of two Strings in Java using the equals() method. This method compares this string to the specified object. The result is true if and only if the argument is not null and is a String object that represents the same sequence of characters as this object.
Can two objects have same hashCode?
It is perfectly legal for two objects to have the same hashcode. If two objects are equal (using the equals() method) then they have the same hashcode. If two objects are not equal then they cannot have the same hashcode.
What is hashCode () in Java?
Java Object hashCode() is a native method and returns the integer hash code value of the object. The general contract of hashCode() method is: Multiple invocations of hashCode() should return the same integer value, unless the object property is modified that is being used in the equals() method.
Why use .equals instead of == Java?
1) use == to compare primitive e.g. boolean, int, char etc, while use equals() to compare objects in Java. 2) == return true if two reference are of same object. Result of equals() method depends on overridden implementation. 3) For comparing String use equals() instead of == equality operator.
Can we compare two strings using == in Java?
equals() method will check if the two strings have the same value. Strings in Java are immutable. … When using == operator for string comparison you are not comparing the contents of the string, but are actually comparing the memory address. If they are both equal it will return true and false otherwise.
What does != Mean in Java?
Not Equal (!=)
The != operator is a comparison operator, also used in conditional expressions. It reads, “not equal”. If the compared values are not equal to each other than the expression returns true.
What is the difference between equals () and == in Java?
We can use == operators for reference comparison (address comparison) and . equals() method for content comparison. In simple words, == checks if both objects point to the same memory location whereas . equals() evaluates to the comparison of values in the objects.
How can I compare two dates in Java?
In Java, two dates can be compared using the compareTo() method of Comparable interface. This method returns ‘0’ if both the dates are equal, it returns a value “greater than 0” if date1 is after date2 and it returns a value “less than 0” if date1 is before date2.
How do I compare two characters in a string in Java?
You can compare two Strings in Java using the compareTo() method, equals() method or == operator. The compareTo() method compares two strings. The comparison is based on the Unicode value of each character in the strings.
Can two keys have same hashCode in Java?
If two keys are the same ( equals() returns true when you compare them), their hashCode() method must return the same number. If keys violate this, then keys that are equal might be stored in different buckets, and the hashmap would not be able to find key-value pairs (because it’s going to look in the same bucket).
What would happen if I only override hashCode?
Only Override HashCode, Use the default Equals: Only the references to the same object will return true. In other words, those objects you expected to be equal will not be equal by calling the equals method. Only Override Equals, Use the default HashCode: There might be duplicates in the HashMap or HashSet.