Java tutorial
/** * Copyright (C) 2016 - present by OpenGamma Inc. and the OpenGamma group of companies * * Please see distribution for license. */ package com.opengamma.strata.collect.io; import java.util.HashMap; import java.util.Locale; import java.util.Map; import java.util.Optional; import java.util.regex.Pattern; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableMap; /** * A row in a CSV file. * <p> * Represents a single row in a CSV file, accessed via {@link CsvFile}. * Each row object provides access to the data in the row by field index. * If the CSV file has headers, the headers can also be used to lookup the fields. */ public final class CsvRow { /** * The header row, ordered as the headers appear in the file. */ private final ImmutableList<String> headers; /** * The header map, transformed for case-insensitive searching. */ private final ImmutableMap<String, Integer> searchHeaders; /** * The fields in the row. */ private final ImmutableList<String> fields; //------------------------------------------------------------------------ /** * Creates an instance, specifying the headers and row. * <p> * See {@link CsvFile}. * * @param headers the headers * @param fields the fields */ private CsvRow(ImmutableList<String> headers, ImmutableList<String> fields) { this.headers = headers; // need to allow duplicate headers and only store the first instance Map<String, Integer> searchHeaders = new HashMap<>(); for (int i = 0; i < headers.size(); i++) { String searchHeader = headers.get(i).toLowerCase(Locale.ENGLISH); searchHeaders.putIfAbsent(searchHeader, i); } this.searchHeaders = ImmutableMap.copyOf(searchHeaders); this.fields = fields; } /** * Creates an instance, specifying the headers and row. * <p> * See {@link CsvFile}. * * @param headers the headers * @param searchHeaders the search headers * @param fields the fields */ CsvRow(ImmutableList<String> headers, ImmutableMap<String, Integer> searchHeaders, ImmutableList<String> fields) { this.headers = headers; this.searchHeaders = searchHeaders; this.fields = fields; } //------------------------------------------------------------------------ /** * Gets the header row. * <p> * If there is no header row, an empty list is returned. * * @return the header row */ public ImmutableList<String> headers() { return headers; } /** * Gets all fields in the row. * * @return the fields */ public ImmutableList<String> fields() { return fields; } /** * Gets the number of fields. * <p> * This will never be less than the number of headers. * * @return the number of fields */ public int fieldCount() { return Math.max(fields.size(), headers.size()); } /** * Gets the specified field. * * @param index the field index * @return the field * @throws IndexOutOfBoundsException if the field index is invalid */ public String field(int index) { if (index >= fields.size() && index < headers.size()) { return ""; } return fields.get(index); } /** * Gets a single field value from the row by header. * <p> * This returns the value of the first column where the header matches the specified header. * Matching is case insensitive. * * @param header the column header * @return the trimmed field value * @throws IllegalArgumentException if the header is not found */ public String getField(String header) { return findField(header).orElseThrow(() -> new IllegalArgumentException("Header not found: " + header)); } /** * Gets a single field value from the row by header. * <p> * This returns the value of the first column where the header matches the specified header. * Matching is case insensitive. * * @param header the column header * @return the trimmed field value, empty if not found */ public Optional<String> findField(String header) { return Optional.ofNullable(searchHeaders.get(header.toLowerCase(Locale.ENGLISH))).map(idx -> field(idx)); } /** * Gets a single field value from the row by header pattern. * <p> * This returns the value of the first column where the header matches the specified header pattern. * * @param headerPattern the header pattern to match * @return the trimmed field value, empty * @throws IllegalArgumentException if the header is not found */ public String getField(Pattern headerPattern) { return findField(headerPattern) .orElseThrow(() -> new IllegalArgumentException("Header pattern not found: " + headerPattern)); } /** * Gets a single field value from the row by header pattern. * <p> * This returns the value of the first column where the header matches the specified header pattern. * * @param headerPattern the header pattern to match * @return the trimmed field value, empty if not found */ public Optional<String> findField(Pattern headerPattern) { for (int i = 0; i < headers.size(); i++) { if (headerPattern.matcher(headers.get(i)).matches()) { return Optional.of(field(i)); } } return Optional.empty(); } //------------------------------------------------------------------------- /** * Obtains a sub-row, containing a selection of fields by index. * <p> * All fields after the specified index are included. * * @param startInclusive the start index, zero-based, inclusive * @return the sub row */ public CsvRow subRow(int startInclusive) { return subRow(startInclusive, fields.size()); } /** * Obtains a sub-row, containing a selection of fields by index. * * @param startInclusive the start index, zero-based, inclusive * @param endExclusive the end index, zero-based, exclusive * @return the sub row */ public CsvRow subRow(int startInclusive, int endExclusive) { return new CsvRow( headers.subList(Math.min(startInclusive, headers.size()), Math.min(endExclusive, headers.size())), fields.subList(startInclusive, endExclusive)); } //------------------------------------------------------------------------- /** * Checks if this CSV file equals another. * <p> * The comparison checks the content. * * @param obj the other file, null returns false * @return true if equal */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (obj instanceof CsvRow) { CsvRow other = (CsvRow) obj; return headers.equals(other.headers) && fields.equals(other.fields); } return false; } /** * Returns a suitable hash code for the CSV file. * * @return the hash code */ @Override public int hashCode() { return headers.hashCode() ^ fields.hashCode(); } /** * Returns a string describing the CSV file. * * @return the descriptive string */ @Override public String toString() { return "CsvRow" + fields.toString(); } }