详解数据分析中的方差，标准差和异常值的使用

Usage

Objects.equal(Object, Object)
Invoking this method then it will avoid the risking of NullPointerException when we need to compare two object whether they equal.

Objects.equal("a", "a"); // return true;
Objects.equal(null, "a"); // return false;
Objects.equal(null, null); // return true;

Objects.hashCode(Object, ....)
Generating hash code with multiple object will be simple. And it also can hash all fields of an Object to get more sensible code value.

// generate hash code with multi object
Objects.hashCode(this.intField, this.charField, this.stringField, this.dateField); 

ComparisonChain
ComparisonChain is a fluent idiom and much more readable. less prone to accidental typos, and smart enough not to do more work than it must.
It only performs comparisons until it finds a non-zero result, after which it ignores further input.

ObjectsTraining objectsTraining = new ObjectsTraining();
int result = ComparisonChain.start()
			   .compare(this.intField, objectsTraining.intField)
             .compare(this.stringField, objectsTraining.stringField)
             .compare(this.charField, objectsTraining.charField)
             .compare(this.dateField, objectsTraining.dateField)
             .result();