Package com.google.common.collect

Class ComparisonChain

  • @GwtCompatible
public abstract class ComparisonChain
extends Object
    A utility for performing a chained comparison statement. For example: 
    
 public int compareTo(Foo that) {
   return ComparisonChain.start()
       .compare(this.aString, that.aString)
       .compare(this.anInt, that.anInt)
       .compare(this.anEnum, that.anEnum, Ordering.natural().nullsLast())
       .result();
 }

    The value of this expression will have the same sign as the first nonzero comparison result in the chain, or will be zero if every comparison result was zero.

    Note: ComparisonChain instances are immutable. For this utility to work correctly, calls must be chained as illustrated above.

    Performance note: Even though the ComparisonChain caller always invokes its compare methods unconditionally, the ComparisonChain implementation stops calling its inputs' compareTo and compare methods as soon as one of them returns a nonzero result. This optimization is typically important only in the presence of expensive compareTo and compare implementations.

    See the Guava User Guide article on ComparisonChain.

    Since:
    2.0
    Author:
    Mark Davis, Kevin Bourrillion