MINOR: Switch anonymous classes to lambda expressions in tools module

[mrsrinivas]

Switch to lambda when ever possible instead of old anonymous way
in tools module

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[mrsrinivas]

ping @guozhangwang @bbejeck @hachikuji for review please.

[ryannedolan]

FWIW, most of these aren't really lambda expressions by most definitions. My rule of thumb for these sort of single-method interfaces is:

• if it's a one-line expression with no side effects, use an inline lambda expression
• otherwise, write a private method and pass a method reference

i.e.

foo(this::bar)
instead of foo(...block of code ...)

my 2 cents.

[ijuma]

Thanks for the PR, left a few minor comments.

[mrsrinivas]

Thank you @ijuma for the review. I addressed all the comments except one. please let me know, if any changes needs to be done for it.

[ijuma]

LGTM

[mrsrinivas]

@omkreddy @vahidhashemian, could you review it when you got sometime ?

[omkreddy]

retest this please

[mrsrinivas]

Fixed the style errors in latest commit. Embedded previous builds status for tracking!

- jdk8-scala2.11

- jdk11-scala2.12

cc: @omkreddy

[omkreddy]

@mrsrinivas I also concur with @ryannedolan . For me, multi-line lambdas are hard to read/understand.
https://developer.ibm.com/articles/j-java8idioms6/

But we can follow whatever best practice/convention is.

[ijuma]

We have been using multi-line lambdas in Scala for a while. Why are we introducing new restrictions for Java?

[omkreddy]

@ijuma Fair point. I was just thinking about java code. I am fine with using multiline lambda as scala code.

[mrsrinivas]

@ijuma @omkreddy, thanks for the review comments. I addressed them in latest commit. Please chack and let me know.

[omkreddy]

@mrsrinivas Thanks for the PR. LGTM.