How to Simplify and Improve Code

Table of Contents

• Remove Redundant
• Inline
• Reduce the nesting/wrapping caused by if or lambda
• Simplify lambda
• Use static import to simplify code
• Import nested class
• Merge
• Avoid String.format when the method already supports formatting
• Method that takes vargs
• Optional
• Misc Tips about Code Simplification

Remove Redundant

• Redundant comments that just repeats code.
• not needed else

Remove implicit

• remove “public final” in interface.
• private in private class
• public in non-public methods

Inline

• inline the message instead of extract it as constant, if the message is used only once (even we may reuse it in future).
• inline a standalone class as an anonymous class or inner class
• merge classes when they are always used together and no reason for each class to exist as a standalone class.
• inline if a variable/method is used only once

Reduce the nesting/wrapping caused by if or lambda

• by extracting methods

Simplify lambda

• Use method reference
• Reduce complex lambda by extracting methods or changing it to method

Use static import to simplify code

• Use static import when the method is clear without additional context of the outer type
• Good static import examples:

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static java.nio.charset.StandardCharsets.UTF_8;

• bad static import examples:

import static com.google.common.base.Optional.of;

Import nested class

import com.google.common.base.Joiner.MapJoiner;

• bad import nested class

import com.google.common.collect.ImmutableSet.Builder;

Merge

• merge multiple consecutive stream.map to one
• merge 2/multiple methods that are always used together
  • generateXTableData and seedXTable into one

Merge multiple if

• merge multiple if
• merge multiple if including implicit

if (request.hasPageSize()) {
  checkArgument(
      request.getPageSize() > 0,
      String.format(
          "Invalid page size: %d, it has to be positive value.", request.getPageSize()));
}
// to
checkArgument(
    !request.hasPageSize() || request.getPageSize() > 0,
    "Invalid page size: %d, it has to be unset or be positive value.",
    request.getPageSize());

Avoid String.format when the method already supports formatting

• like Preconditions.checkArgument

Method that takes vargs

• install(A.class);install(B.class);... to install(A.class, B.class, C.class)

Optional

• Check Use Optional class to Avoid NullPointerException
• Check Java Optional Best Practices
• if(optional.isPresent()) can be simplifed as optional.orElse/orElseThrow

Misc Tips about Code Simplification

• Use other util methods or test rule.
• early return (with the negative condition)