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«abstract»

DataMiner

+ mine() «final»

# openFile()*

# extract()*

# parse()*

# summary() hook

PdfMiner

# openFile()

# extract()

# parse()

CsvMiner

# openFile()

# extract()

# summary()

Skeleton in the base, steps in subclasses

 1abstract class DataMiner {
 2    final void mine() {              // skeleton — locked
 3        openFile(); extract(); parse(); summary();
 4    }
 5    protected abstract void openFile();   // primitive
 6    protected abstract void extract();    // primitive
 7    protected abstract void parse();      // primitive
 8    protected void summary() {}           // hook (no-op)
 9}
10 
11class PdfMiner extends DataMiner { /* override the 3 primitives */ }
12class CsvMiner extends DataMiner { /* override primitives + summary() hook */ }

State

mine()fixed skeleton (final)