Freaks City

What is a Hash Collision? When discussing hash collisions, we need to understand the fundamental issue: different objects processed through the same hash algorithm produce identical hash values. Consider HashMap's internal structure—a combination of an array with linked lists. When a key-value pair is inserted, the hash code determines which ar ...

String Class in Java The String class in Java represents sequences of characters and is used for text data manipulation. String Creation and Operations Strings can be created using literals or the new keyword: String greeting = "Hello"; String message = new String("Welcome"); Common string operations include: Length: int ...

Understanding Java's Object Class The Object class serves as the root of the Java class hierarchy. Every class in Java implicitly extends Object, granting access to all Object class methods. Located in the java.lang package, Object is automatically imported during compilation. When defining a class without explicit inheritance, it becomes an Ob ...

The Default Behavior of equals() In java.lang.Object, the base implementation simply checks reference identity: public boolean equals(Object obj) { return (this == obj); } Without overriding, two distinct instances are never equal, even if they hold identical field values. A typical custom implementation compares logical attributes: class ...

When sharding data by a non-integer primary key or a composite key (usually concatenated in to a string), developers often rely on Java's built-in String.hashCode() method to derive a hash value, which is then used for modulo-based sharding. While convenient, this approach can produce negative hash codes, leading to invalid shard numbers. Under ...

Entity Class Definition Let's define a simple Rectangle class that overrides the equals method to compare objects based on their width and height values instead of reference equality. class Rectangle { private int width; private int height; public int getWidth() { return width; } public void setWidth(int width) { ...

In Java, the HashMap implementation uses the hashCode() method to determine the storage bucket for a key and the equals() method to check for key equality. The default implementation in the Object class generates a hash code based on the object's memory address. This behavior creates a problem when using custom objects as keys: two distinct ins ...