Using Java 8 lambdas to lift the exceptions and remove boiler plate try-catch

BankAPIsClient.java

package lambdas;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;
import java.util.function.Function;

/**
 * Created by gabbi on 19/10/14.
 */
public class BankAPIsClient {
    public static void main(String... args) throws AccountMgrException, LoanManagerException {
        RecordsFetcher delegator = new RecordsFetcher();

        new AccountManager(delegator).getAccountsDetails();

        new LoanManager(delegator).getLoanRecords();
    }
}

class AccountManager {
    private final RecordsFetcher delegator;

    public AccountManager(RecordsFetcher delegator) {
        this.delegator = delegator;
    }

    public java.util.List<String> getAccountsDetails() throws AccountMgrException {
        return delegator.perform("/sm/path/to/Account/Records/", ex -> new AccountMgrException(ex, "Error during Fetch"));
    }

    public java.util.List<String> getAccountsDetailsNormalWay() throws AccountMgrException {
        try {
            //a low level API to get data from IO or over the wire
            return delegator.perform("/sm/path/to/Account/Records/");
        } catch (IOException e) {
            //logging can be done here
            throw new AccountMgrException(e, "Error during Fetch");
        }
    }
}

class AccountMgrException extends Exception {
    public AccountMgrException(Exception ex, String message) {
        super(message, ex);
    }
}

class LoanManager {
    private final RecordsFetcher recordFetcher;


    public LoanManager(RecordsFetcher fetcher) {
        this.recordFetcher = fetcher;
    }

    public java.util.List<String> getLoanRecords() throws LoanManagerException {
        return recordFetcher.perform("/sm/path/to/Loan/Records/", ex -> new LoanManagerException("Error fetching loan records", ex));
    }
}

class LoanManagerException extends Exception {
    public LoanManagerException(String message, Exception ex) {
        super(message, ex);
    }
}

class RecordsFetcher {
    public <E extends Exception> java.util.List<String> perform(String fileName, Function<IOException, E> exceptionLifter) throws E {
        try {
            return Files.readAllLines(Paths.get(fileName));
        } catch (IOException e) {
            //logging can be added here
            throw exceptionLifter.apply(e);
        }
    }

    public List<String> perform(String path) throws IOException {
        return perform(path, ex -> ex);
    }
}