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[Jakarta Commons筆記](méi) 代碼范例 - ArrayUtils

數(shù)組是我們經(jīng)常需要使用到的一種數(shù)據(jù)結(jié)構(gòu)，但是由于Java本身并沒(méi)有提供很好的API支持，使得很多操作實(shí)際上做起來(lái)相當(dāng)繁瑣，以至于我們實(shí)際編碼中甚至?xí)幌奚阅苋ナ褂?/span>Collections API，用Collection當(dāng)然能夠很方便的解決我們的問(wèn)題，但是我們一定要以性能為代價(jià)嗎？ArrayUtils幫我們解決了處理類似情況的大部分問(wèn)題。來(lái)看一個(gè)例子：

package sean.study.jakarta.commons.lang;

import java.util.Map;

import org.apache.commons.lang.ArrayUtils;

public class ArrayUtilsUsage {

    public static void main(String[] args) {

        // data setup

        int[] intArray1 = { 2, 4, 8, 16 };

        int[][] intArray2 = { { 1, 2 }, { 2, 4 }, { 3, 8 }, { 4, 16 } };

        Object[][] notAMap = {

                { "A", new Double(100) },

                { "B", new Double(80) },

                { "C", new Double(60) },

                { "D", new Double(40) },

                { "E", new Double(20) }

        };

        // printing arrays

        System.out.println("intArray1: " + ArrayUtils.toString(intArray1));

        System.out.println("intArray2: " + ArrayUtils.toString(intArray2));

        System.out.println("notAMap: " + ArrayUtils.toString(notAMap));

        // finding items

        System.out.println("intArray1 contains '8'? "

                + ArrayUtils.contains(intArray1, 8));

        System.out.println("intArray1 index of '8'? "

                + ArrayUtils.indexOf(intArray1, 8));

        System.out.println("intArray1 last index of '8'? "

                + ArrayUtils.lastIndexOf(intArray1, 8));

        // cloning and resversing

        int[] intArray3 = ArrayUtils.clone(intArray1);

        System.out.println("intArray3: " + ArrayUtils.toString(intArray3));

        ArrayUtils.reverse(intArray3);

        System.out.println("intArray3 reversed: "

                + ArrayUtils.toString(intArray3));

        // primitive to Object array

        Integer[] integerArray1 = ArrayUtils.toObject(intArray1);

        System.out.println("integerArray1: "

                + ArrayUtils.toString(integerArray1));

        // build Map from two dimensional array

        Map map = ArrayUtils.toMap(notAMap);

        Double res = (Double) map.get("C");

        System.out.println("get 'C' from map: " + res);

    }

}

以下是運(yùn)行結(jié)果：

intArray1: {2,4,8,16}

intArray2: {{1,2},{2,4},{3,8},{4,16}}

notAMap: {{A,100.0},{B,80.0},{C,60.0},{D,40.0},{E,20.0}}

intArray1 contains '8'? true

intArray1 index of '8'? 2

intArray1 last index of '8'? 2

intArray3: {2,4,8,16}

intArray3 reversed: {16,8,4,2}

integerArray1: {2,4,8,16}

get 'C' from map: 60.0

posted on 2006-03-10 23:06 Vincent.Chen 閱讀(135) 評(píng)論(0)  編輯  收藏 所屬分類: Java