Java tutorial
/* * Copyright 2015-2020 Fengduo.com All right reserved. This software is the confidential and proprietary information of * Fengduo.com ("Confidential Information"). You shall not disclose such Confidential Information and shall use it only * in accordance with the terms of the license agreement you entered into with Fengduo.com. */ package com.fengduo.bee.commons.core.lang; import java.lang.reflect.Array; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.Iterator; import java.util.List; import org.apache.commons.lang.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * ?? * * @author zxc May 28, 2015 12:01:48 AM */ public class ArrayUtils { private static final Logger logger = LoggerFactory.getLogger(ArrayUtils.class); public interface IHandle<T> { // ? public T init(Class<T> clazz); // null public boolean isNull(T obj); } public static <E extends Object> List<E> arrayConvert(E[] array) { return Argument.isEmptyArray(array) ? Collections.<E>emptyList() : Arrays.asList(array); } @SuppressWarnings("unchecked") public static <E extends Object> E[] listConvert(List<E> list) { return Argument.isEmpty(list) ? null : (E[]) list.toArray(); } public static <T extends Object> String[] convert(T[] array) { if (Argument.isEmptyArray(array)) { logger.debug("ArrayUtils.convert array is null!"); return null; } String[] result = new String[array.length]; for (int i = 0, j = result.length; i < j; i++) { result[i] = array[i].toString(); } return result; } public static String[] removeBlankElement(String[] array) { if (Argument.isEmptyArray(array)) { logger.debug("ArrayUtils.removeBlankElement array is null!"); return null; } List<String> list = new ArrayList<String>(Arrays.asList(array)); Iterator<String> iterator = list.iterator(); while (iterator.hasNext()) { if (Argument.isBlank(iterator.next())) { iterator.remove(); } } if (list.isEmpty()) { return null; } else { return list.toArray(new String[0]); } } @SuppressWarnings("unchecked") public static <E> E[] removeNullElement(E[] array) { if (Argument.isEmptyArray(array)) { logger.debug("ArrayUtils.removeNullElement array is null!"); return null; } int notNullValueCount = array.length; for (int i = 0, j = array.length; i < j; i++) { if (array[i] == null) { notNullValueCount--; } } if (notNullValueCount == 0) { return null; } E[] newInstance = (E[]) Array.newInstance(array.getClass().getComponentType(), notNullValueCount); for (int i = 0, j = 0; i < array.length; i++) { if (array[i] != null) { newInstance[j++] = array[i]; } } return newInstance; } @SuppressWarnings({ "rawtypes", "unchecked" }) public static <E> E[] replaceNullElement(E[] array, IHandle handle) { if (handle == null) { logger.error("ArrayUtils.replaceNullElement handle is null!"); throw new RuntimeException(); } if (Argument.isEmptyArray(array)) { return null; } for (int i = 0, j = array.length; i < j; i++) { if (array[i] == null || handle.isNull(array[i])) { array[i] = (E) handle.init(array.getClass().getComponentType()); } } return array; } /** * */ public static <T extends Object> T[] shift(T[] array, T newValue) { return add(array, array == null ? 0 : array.length, newValue); } /** * */ public static <T extends Object> T[] unshift(T[] array, T newValue) { return add(array, 0, newValue); } /** * <pre> * ?? * ?index??index? [-1,length] * ?indexlength * </pre> */ @SuppressWarnings("unchecked") public static <T extends Object> T[] add(T[] array, int index, T newValue) { int length = array == null ? 0 : array.length; index = Math.max(0, index); index = Math.min(length, index); Class<?> clazz = array == null ? newValue.getClass() : array.getClass().getComponentType(); T[] newInstance = (T[]) Array.newInstance(clazz, length + 1); for (int i = 0, j = 0; i < newInstance.length;) { T _value = i == index ? newValue : array[j++]; newInstance[i++] = _value; } return newInstance; } public static void main(String[] args) { String[] s = { "zxc", null, "msunmss", "" }; s = ArrayUtils.replaceNullElement(s, new IHandle<String>() { @Override public boolean isNull(String obj) { return obj == null || StringUtils.isEmpty((String) obj); } @Override public String init(Class<String> clazz) { if (clazz.equals(String.class)) { return (String) new String("wu"); } try { return clazz.newInstance(); } catch (InstantiationException e) { System.out.println(e.getMessage()); } catch (IllegalAccessException e) { System.out.println(e.getMessage()); } System.out.println("replaceNullElement: init error"); return null; } }); System.out.println(StringUtils.join(s, ";")); String[] a = removeBlankElement(new String[] { "1", null, "2", "", "3" }); for (int i = 0, j = a.length; i < j; i++) { System.out.println(a[i]); } String[] t = null; System.out.println("Orignal:" + org.apache.commons.lang.ArrayUtils.toString(t, "NULL")); System.out.println("shift:" + org.apache.commons.lang.ArrayUtils.toString(shift(t, "a"), "NULL")); System.out.println("unshift:" + org.apache.commons.lang.ArrayUtils.toString(unshift(t, "a"), "NULL")); System.out.println("add(-1):" + org.apache.commons.lang.ArrayUtils.toString(add(t, -1, "a"), "NULL")); System.out.println("add(0):" + org.apache.commons.lang.ArrayUtils.toString(add(t, 0, "a"), "NULL")); System.out.println("add(length):" + org.apache.commons.lang.ArrayUtils.toString(add(t, 0, "a"), "NULL")); System.out.println("add(length+1):" + org.apache.commons.lang.ArrayUtils.toString(add(t, 1, "a"), "NULL")); t = new String[] { "1", null, "2", "", "3" }; System.out.println("Orignal:" + org.apache.commons.lang.ArrayUtils.toString(t, "NULL")); System.out.println("shift:" + org.apache.commons.lang.ArrayUtils.toString(shift(t, "a"), "NULL")); System.out.println("unshift:" + org.apache.commons.lang.ArrayUtils.toString(unshift(t, "a"), "NULL")); System.out.println("add(-1):" + org.apache.commons.lang.ArrayUtils.toString(add(t, -1, "a"), "NULL")); System.out.println("add(0):" + org.apache.commons.lang.ArrayUtils.toString(add(t, 0, "a"), "NULL")); System.out.println("add(length):" + org.apache.commons.lang.ArrayUtils.toString(add(t, 0, "a"), "NULL")); System.out.println("add(length+1):" + org.apache.commons.lang.ArrayUtils.toString(add(t, 1, "a"), "NULL")); } }