Java tutorial
//package com.java2s; /* * Copyright (C) 2014 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import android.util.Log; import java.util.ArrayList; import java.util.List; import java.util.Objects; public class Main { private static final String TAG = "ArrayUtils"; /** * Create an {@code int[]} from the {@code List<>} by using {@code convertFrom} and * {@code convertTo} as a one-to-one map (via the index). * * <p>Strings not appearing in {@code convertFrom} are ignored (with a logged warning); * strings appearing in {@code convertFrom} but not {@code convertTo} are silently * dropped.</p> * * @param list Source list of strings * @param convertFrom Conversion list of strings * @param convertTo Conversion list of ints * @return An array of ints where the values correspond to the ones in {@code convertTo} * or {@code null} if {@code list} was {@code null} */ public static int[] convertStringListToIntArray(List<String> list, String[] convertFrom, int[] convertTo) { if (list == null) { return null; } List<Integer> convertedList = convertStringListToIntList(list, convertFrom, convertTo); int[] returnArray = new int[convertedList.size()]; for (int i = 0; i < returnArray.length; ++i) { returnArray[i] = convertedList.get(i); } return returnArray; } /** * Create an {@code List<Integer>} from the {@code List<>} by using {@code convertFrom} and * {@code convertTo} as a one-to-one map (via the index). * * <p>Strings not appearing in {@code convertFrom} are ignored (with a logged warning); * strings appearing in {@code convertFrom} but not {@code convertTo} are silently * dropped.</p> * * @param list Source list of strings * @param convertFrom Conversion list of strings * @param convertTo Conversion list of ints * @return A list of ints where the values correspond to the ones in {@code convertTo} * or {@code null} if {@code list} was {@code null} */ public static List<Integer> convertStringListToIntList(List<String> list, String[] convertFrom, int[] convertTo) { if (list == null) { return null; } List<Integer> convertedList = new ArrayList<>(list.size()); for (String str : list) { int strIndex = getArrayIndex(convertFrom, str); // Guard against unexpected values if (strIndex < 0) { Log.w(TAG, "Ignoring invalid value " + str); continue; } // Ignore values we can't map into (intentional) if (strIndex < convertTo.length) { convertedList.add(convertTo[strIndex]); } } return convertedList; } /** Return the index of {@code needle} in the {@code array}, or else {@code -1} */ public static <T> int getArrayIndex(T[] array, T needle) { if (array == null) { return -1; } int index = 0; for (T elem : array) { if (Objects.equals(elem, needle)) { return index; } index++; } return -1; } /** Return the index of {@code needle} in the {@code array}, or else {@code -1} */ public static int getArrayIndex(int[] array, int needle) { if (array == null) { return -1; } for (int i = 0; i < array.length; ++i) { if (array[i] == needle) { return i; } } return -1; } }