Why is this an issue?

Naming a method tostring, hashcode or equal is either:

• A bug in the form of a typo. Overriding toString, Object.hashCode() (note the camelCasing) or Object.equals (note the 's' on the end) was meant, and the application does not behave as expected.
• Done on purpose. The name however will confuse every other developer, who may not notice the naming difference, or who will think it is a bug.

In both cases, the method should be renamed.

Noncompliant code example

public int hashcode() { /* ... */ }  // Noncompliant

public String tostring() { /* ... */ } // Noncompliant

public boolean equal(Object obj) { /* ... */ }  // Noncompliant

Compliant solution

@Override
public int hashCode() { /* ... */ }

@Override
public String toString() { /* ... */ }

@Override
public boolean equals(Object obj) { /* ... */ }