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package u;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

public abstract class Utils {

    public interface IExecutor {
        public void pre();
        public void exec(String line);
        public void post();
    }

    abstract static public class AbstractExecutor implements IExecutor{
        public void pre(){}
        public void exec(String line){}
        public void post(){}
    }
    
    /**
     * implement 
     * use  BufferedReader
     * 
     * @param file
     * @param executor
     * @return
     * @throws IOException
     */
    public static IExecutor readLine(File file, IExecutor executor)
            throws IOException {
        BufferedReader reader = new BufferedReader(new FileReader(file));

        try {
            executor.pre();
            String line = null;
            while ((line = reader.readLine()) != null) {
                executor.exec(line);
            }

        } finally {
            try {
                reader.close();
            } finally {
                executor.post();
            }

        }

        return executor;
    }

    

}