java - local::reference passing along a reference to local -

i have constructor looks follows:

public sqlreader(schema schema) {   super(schema::readrow,schema::initialize); } 

the main part of code follows:

schema schema = new schema(schemadefinition); sqlreader sqlsource = new sqlreader(schema); schema.groupby(sqlsource,column.column("market"),column.sum("sales")); result = schema.execute(); 

this fictional piece of code allow me explain dealing here lazy execution, schema.groupby modify schema, , sqlreader depends on original schema.

the problem here using schema::readrow, pass along actual reference schema member reference , not copy of it, translates anonymous inner class pass along schema.

how can efficiently improved?

a first attempt might follows:

public sqlreader(schema schema) {   super(schema.clone()::readrow,schema.clone()::initialize); } 

overhead obvious: have created twice clone. might come solution, instead of in api (sqlreader), in custom coded part:

sqlreader sqlsource = new sqlreader(schema.clone()); 

issue here require user of api aware of issue, might complex of topic user understand or remember.

so come new approach: using factory, builder, or static creator:

public static create(schema schema) {   schema schemacopy = schema.clone();   return new sqlreader(schemacopy::readrow,schemacopy::initialize); } 

it seems such common issue parallelized streams, lambda, , method references, there must more elegant way address this?