Collate objects with null in ShardingShpere

[Myth]

Hi,All the friends of ShardingShpere community.
We judge the use of null in ShardingShpere, sorted out 7 types.
We have suggested changes to some of the code, and we hope that the community 
will provide your valuable Suggestions as well.

1 : To determine whether the object is null, then need to transform it. Here 
are some examples.

  1.1
    current code ??null == dataSourceName ? 
databaseEnvironment.getURL()              
               
                      
           : 
databaseEnvironment.getURL(dataSourceName)
    advice  code ??Optional.ofNullable(dataSourceName)
                      
          
 .map(databaseEnvironment::getURL).orElse(databaseEnvironment.getURL())
      
  1.2
    current code ?? return null == loadBalanceStrategyConfiguration ? 
serviceLoader.newService()              
                      
      
                               
       : 
serviceLoader.newService(loadBalanceStrategyConfiguration.getType(),
                      
                      
                      
   loadBalanceStrategyConfiguration.getProperties());
    advice  code ?? return 
Optional.ofNullable(loadBalanceStrategyConfiguration)
                              
       .map(e -> 
serviceLoader.newService(e.getType(),e.getProperties()))
                      
              
 .orElse(serviceLoader.newService())
                           
       

  1.3
    current code ?? return null == 
shardingRuleConfig.getDefaultKeyGeneratorConfig() ? null 
                      
                      
  : 
shardingRuleConfig.getDefaultKeyGeneratorConfig().getColumn();                    
       
    advice  code ?? return 
Optional.ofNullable(shardingRuleConfig.getDefaultKeyGeneratorConfig())
                      
                    
 .map(KeyGeneratorConfiguration::getColumn).orElse(null)
                    
       
  1.4
    current code ?? return null == shardingStrategyConfiguration ? 
new NoneShardingStrategy()              
                  
                      
                      
 : 
ShardingStrategyFactory.newInstance(shardingStrategyConfiguration);            
       
    advice  code ?? return 
Optional.ofNullable(shardingStrategyConfiguration)
                      
                      
.map(ShardingStrategyFactory::newInstance)
                      
                      
.orElse(new NoneShardingStrategy())
                
       

2 : Object is judged with null. Here are some examples.

  2.1
    current code ??
       public void xxx??Object o??{
           if(null == o){
             retrun;
           }
       }

  2.2
    current code ??
       public boolean wasNull() {
          return null == currentRow;
       }

  advice : Use the objects.isNull() provided by JDK8.

3 : Use the ternary operator to determine whether the object is null, then 
returns itself or other. Here are some examples.

  3.1
    current code ?? this.loadBalanceAlgorithm = null == 
loadBalanceAlgorithm 
                      
                      ? 
new MasterSlaveLoadBalanceAlgorithmServiceLoader().newService() 
                      
                      : 
loadBalanceAlgorithm;        
    advice  code ?? this.loadBalanceAlgorithm = 
Optional.ofNullable(loadBalanceAlgorithm)
                      
                      
.orElse(new MasterSlaveLoadBalanceAlgorithmServiceLoader().newService())

  3.2
    current code ?? currentDataSourceName = null == 
currentDataSourceName 
                      
                      
      ? 
shardingRule.getShardingDataSourceNames().getRandomDataSourceName() 
                      
                      
      : currentDataSourceName;
    advice  code ?? currentDataSourceName = 
Optional.ofNullable(currentDataSourceName)
                      
                      
      
.orElse(shardingRule.getShardingDataSourceNames().getRandomDataSourceName())


                     
      
  3.3
    current code ?? return null == 
tableRule.getDatabaseShardingStrategy() 
                      
                      ? 
defaultDatabaseShardingStrategy : tableRule.getDatabaseShardingStrategy();
    advice  code ?? return 
Optional.ofNullable(tableRule.getDatabaseShardingStrategy())
                      
                      
.orElse(defaultDatabaseShardingStrategy)

  3.4
    current code ?? return null == results.get(0) ? 0 : 
results.get(0);
    advice  code ?? return 
Optional.ofNullable(results.get(0)).orElse(0);

  3.5
    current code ?? return null == getSqlStatement().getTable() ? 
Collections.emptyList()
                      
                      
 : Collections.singletonList(getSqlStatement().getTable());
    advice  code ?? return 
Optional.ofNullable(getSqlStatement().getTable())
                      
                      
 .map(Collections::singletonList).orElse(Collections.emptyList());


4 :  Get the value of the Map by key, and then determines that the value 
is null. Here are some examples.

  4.1
    current code ??
&nbsp;&nbsp; &nbsp; &nbsp; public Collection<String&gt; 
getActualTableNames(final String targetDataSource) {
&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; Collection<String&gt; result = 
datasourceToTablesMap.get(targetDataSource);
&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; if (null == result) {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; result = 
Collections.emptySet();
&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; }
&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; return result;
&nbsp;&nbsp; &nbsp; &nbsp; }

&nbsp; &nbsp; advice code : Use Map.getOrDefault().
&nbsp; &nbsp; &nbsp; &nbsp; public Collection<String&gt; 
getActualTableNames(final String targetDataSource) {
&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; return 
datasourceToTablesMap.getOrDefault(targetDataSource, Collections.emptySet());
&nbsp; &nbsp; &nbsp; &nbsp; }


5 : To determine whether the object is null, but returns Optional wrapped. Here 
are some examples.

&nbsp; 5.1
&nbsp; &nbsp; current code ?? return null == alias ? Optional.empty() : 
Optional.ofNullable(alias.getIdentifier().getValue());
&nbsp; &nbsp; advice&nbsp; code ?? return Optional.ofNullable(alias).map(e 
-&gt; e.getIdentifier().getValue());


6 : Determine if the object is null, throw exception, and proceed to the next 
step. Here are some examples.

&nbsp; 6.1
&nbsp; &nbsp; current code ??
&nbsp;&nbsp; &nbsp; &nbsp; private Collection<String&gt; doSharding(final 
Collection<String&gt; availableTargetNames, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
final RangeRouteValue<?&gt; shardingValue) {
&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; if (null == rangeShardingAlgorithm) {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; throw new 
UnsupportedOperationException("Cannot find range sharding strategy in sharding 
rule.");
&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; }
&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; return 
rangeShardingAlgorithm.doSharding(availableTargetNames,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; new 
RangeShardingValue(shardingValue.getTableName(), shardingValue.getColumnName(), 
shardingValue.getValueRange()));
&nbsp;&nbsp; &nbsp; &nbsp; }

&nbsp; &nbsp; advice&nbsp; code ??
&nbsp;&nbsp; &nbsp; &nbsp; private Collection<String&gt; doSharding(final 
Collection<String&gt; availableTargetNames, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;final 
RangeRouteValue<?&gt; shardingValue) {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; return 
Optional.ofNullable(rangeShardingAlgorithm).map(e -&gt; 
e.doSharding(availableTargetNames,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 &nbsp; &nbsp; &nbsp; new RangeShardingValue(shardingValue.getTableName(), 
shardingValue.getColumnName(), shardingValue.getValueRange())))
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 &nbsp; &nbsp; &nbsp; .orElseThrow(()-&gt; new 
UnsupportedOperationException("Cannot find range sharding strategy in sharding 
rule."));
&nbsp;&nbsp; &nbsp; &nbsp; }

7 : Judge Collection is Empty. Here are some examples.

&nbsp; 7.1
&nbsp; &nbsp; current code ??
&nbsp;&nbsp; &nbsp; &nbsp; private boolean isEmptyDataNodes(final 
List<String&gt; dataNodes) {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; return null == dataNodes || 
dataNodes.isEmpty();
&nbsp;&nbsp; &nbsp; &nbsp; }

&nbsp; &nbsp; advice ??Unify judgment with Collection Tool.

Thank you for wasting your precious time reading, and the ShardingShpere 
community welcomes your best Suggestions for the above code.