RuleKey (Buck)

java.lang.Object
- com.facebook.buck.core.rulekey.RuleKey

```
public class RuleKey
extends Object
```
RuleKey encapsulates regimented computation of SHA-1 keys that incorporate all BuildRule state relevant to idempotency. The RuleKey.Builder API conceptually implements the construction of an ordered map, and the key/val pairs are digested using an internal serialization that guarantees a 1:1 mapping for each distinct vector of keys <header,k1,...,kn> in RuleKey.builder(header).set(k1, v1) ... .set(kn, vn).build().
Note carefully that in order to reliably avoid accidental collisions, each RuleKey schema, as defined by the key vector, must have a distinct header. Otherwise it is possible (if unlikely) for serialized value data to alias serialized key data, with the result being identical RuleKeys for differing input. In practical terms this means that each BuildRule implementer should specify a distinct header, and that for all RuleKeys built with a particular header, the sequence of set() calls should be identical, even if values are missing. The set() methods specifically handle null values to accommodate this regime.

Constructor Summary

Constructors
Constructor Description

RuleKey(com.google.common.hash.HashCode hashCode)

RuleKey(String hashString)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`equals(Object obj)`
`com.google.common.hash.HashCode`	`getHashCode()`
`int`	`hashCode()`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - RuleKey
```
public RuleKey(com.google.common.hash.HashCode hashCode)
```
  - RuleKey
```
public RuleKey(String hashString)
```
    Parameters:
    
    hashString - string that conforms to the contract of the return value of HashCode.toString().
- Method Detail
  - getHashCode
```
public com.google.common.hash.HashCode getHashCode()
```
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
    
    Returns:
    
    the toString() of the hash code that underlies this RuleKey.
  - equals
```
public boolean equals(@Nullable
                      Object obj)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object