数组工具类 - ArrayUtil.java
数组工具类,提供数组、对象之间转换的方法。
源码如下:(点击下载 - ArrayUtil.java 、commons-lang-2.6.jar)
import java.lang.reflect.Array; import java.util.Collection; import java.util.Iterator; import org.apache.commons.lang.StringUtils; /** * 数组工具类 * */ public class ArrayUtil { private transient static final String DEFAULT_JOIN_STR = ","; /** * 连接字符串 如:[1,2,3,4],将会返回"1,2,3,4" * * @param arr * an array of {@link java.lang.Object} objects. * @return a {@link java.lang.String} object. */ public static final String join(final Object[] arr) { return join(arr, DEFAULT_JOIN_STR); } /** * 连接字符串 如: join([1,2,3,4],"x"]) 将会返回"1x2x3x4" * * @param arr * an array of {@link java.lang.Object} objects. * @param joinStr * a {@link java.lang.String} object. * @return a {@link java.lang.String} object. */ public static final String join(final Object[] arr, final String joinStr) { if (arr == null || arr.length < 1) { return StringUtils.EMPTY; } final StringBuffer sb = new StringBuffer(String.valueOf(arr[0])); for (int i = 1, len = arr.length; i < len; i++) { sb.append(StringUtils.isNotEmpty(joinStr) ? joinStr : StringUtils.EMPTY).append(String.valueOf(arr[i])); } return sb.toString(); } /** * 集合转数组 * * @param collection * 集合 * @param clazz * 类型 * @return 数组 * @param <T> * a T object. */ @SuppressWarnings("unchecked") public static final <T> T[] toArray(final Collection<T> collection, final Class<T> clazz) { if (collection == null) { return null; } final T[] arr = (T[]) Array.newInstance(clazz, collection.size()); return collection.toArray(arr); } /** * 集合转对象数组 * * @param collection * 集合 * @return 对象数组 */ public static final Object[] toObjectArray(final Collection<?> collection) { if (collection == null) { return null; } final Object[] arr = (Object[]) Array.newInstance(Object.class, collection.size()); int i = 0; for (Iterator<?> it = collection.iterator(); it.hasNext();) { arr[i++] = it.next(); } return arr; } }
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