Use as many lambda function
expressions as possible.
Method parameters must be modified with final
.
Constants modified static final
must be named in upper case.
Methods should not have too many parameters.
Clear unused classes and methods.
Use linux line separators.
Tab size is 4 and keep indents on empty lines.
All code passage of Checkstyle: https://github.com/apache/shenyu/blob/master/script/shenyu_checkstyle.xml
When adding a new file, you need to add the apache protocol in the header of the file.
Optional.ofNullable(xxx).orElse(obj)
Objects.isNull(obj) OR Objects.nonNull(obj)
Objects.equals
Judgment are they equal.Objects.equals(obj1, obj2)
Object object = null; for () { object = new Object(); }
Use LinkedList
when you need to add or delete elements, Else use ArrayList
.
Use org.apache.commons.collections4.CollectionUtils
Judgment Is empty Or Not empty.
CollectionUtils.isEmpty(list) or CollectionUtils.isNotEmpty(data)
Use ConcurrenHashMap
when considering concurrency of threads, Else use HashMap
.
Iterate over map using the most efficient way Or use lambda function
.
Set<Map.Entry<String, String>> entrySet = map.entrySet(); Iterator<Map.Entry<String, String>> iter = entrySet.iterator(); while (iter.hasNext()) { Map.Entry<String, String> entry = iter.next(); }
org.apache.commons.lang3.StringUtils
Judgment Is empty Or Not empty.StringUtils.isEmpty(list) or StringUtils.isNotEmpty(data)
String.join
should be used when string concatenation occurs.String join(CharSequence delimiter, CharSequence... elements)
try { for () { } } catch () { }
Do not use printStackTrace()
.
Please use custom exceptions or ShenyuException
.
try with resource
to close resource.Judge self if Null or not, and also need to transform self, below are some representative examples:
current : result.setXXX(null == a ? b.getXXX() : b.getXXX(a));
recommendation : Optional.ofNullable(a).map(b::getXXX).orElse(b.getXXX());
current : return null == a ? b.newC() : b.newC(a.getD(), a.getE());
recommendation : return Optional.ofNullable(a).map(e -> b.newC(e.getD(),e.getE())).orElse(b.newC());
current : return null == a.getB() ? null : a.getB().getC();
recommendation : return Optional.ofNullable(a.getB()).map(C::getD).orElse(null);
current : return null == a ? new B() : C.newD(a);
recommendation : return Optional.ofNullable(a).map(B::newC).orElse(new D());
Directly compare current object with Null, below are some representative examples:
current : public void xxx(Object o){if(null == o){retrun;}}
current : public boolean wasNull() {return null == currentRow;}
recommendation :Use JDK8's Objects.isNull method.
Judge self if Null or not, and also need to return self related ternary operator, below are some representative examples:
current : this.a = null == a ? new B().newC() : a;
recommendation : Optional.ofNullable(a).orElse(new B().newC());
current : a = null == a ? b.getC().getD() : a;
recommendation : a = Optional.ofNullable(a).orElse(b.getC().getD());
current : return null == a.getB() ? c : a.getB();
recommendation : return Optional.ofNullable(a.getB()).orElse(c);
current :
BigDecimal c; BigDecimal s; if (null == c) { c = new BigDecimal("0"); } if (null == s) { s = new BigDecimal("0"); }
recommendation : c = Optional.ofNullable(c).orElse(new BigDecimal("0")); s = Optional.ofNullable(s).orElse(new BigDecimal("0"));
current : return null == results.get(0) ? 0 : results.get(0);
recommendation : return Optional.ofNullable(results.get(0)).orElse(0);
current : return null == getA().getB() ? Collections.emptyList() : Collections.singletonList(getA().getB());
recommendation : return Optional.ofNullable(getA().getB()).map(Collections::singletonList).orElse(Collections.emptyList());
Judge self if Null or not, and also need to return self independent ternary operator, below are some representative examples:
current : A a = null == b ? cMap.values().iterator().next() : cMap.get(d);
current : return null == a ? new B() : new B(c);
recommendation : No modification.
Judge collection is null or not, below are some representative examples:
current :
private boolean isEmpty(final List<String> xxx) { return null == xxx || xxx.isEmpty(); }
recommendation : Add a collection tool class to make unified judgment.
Judge Map's value is Null or not, below are some representative examples:
current :
public Collection<String> getA(final String b) { Collection<String> result = cMap.get(b); if (null == result) { result = Collections.emptySet(); } return result; }
recommendation : Use Map.getOrDefault() method.
public Collection<String> getA(final String b) { return cMap.getOrDefault(b, Collections.emptySet()); }
Judge is Null or not, if yes throw exception, else execute next step, below are some representative examples:
current :
private Collection<String> doXxx(final Collection<String> a, final Object<?> b) { if (null == c) { throw new Exception("XXX"); } return c.doXxx(a,new Object(b.getXXX(), b.getXXX(), b.getXXX())); }
recommendation :
private Collection<String> doXxx(final Collection<String> a, final Object<?> b) { return Optional.ofNullable(c).map(e -> e.doXxx(a, new Object(b.getXXX(), b.getXXX(), b.getXXX()))) .orElseThrow(()-> new Exception("XXX")); }
Judge is Null or not, and return Optional wrapped object, below are some representative examples:
current : return null == a ? Optional.empty() : Optional.ofNullable(a.getXXX());
recommendation : return Optional.ofNullable(a).map(e -> e.getXXX());