本套JAVA8教程由于是有英文翻译过来的,如果有翻译不对的地方还请多多包涵。

本节课先简单的介绍下Java8有哪些新特性,对于Java6/7版本做出哪些更改.那废话不多说,赶紧开始今天的课程吧.

在本文中，我们将向您展示一些加入Java Array的方法。

Apache Commons Lang – ArrayUtils
Java API
Java 8 Stream

Apache Commons Lang – ArrayUtils

最简单的方法是添加Apache Commons Lang库，并使用ArrayUtils。
addAll用于连接数组。
此方法支持基本类型和对象类型数组。

public static void main(String[] args) {

        String[] s1 = new String[]{"a", "b", "c"};
        String[] s2 = new String[]{"d", "e", "f"};
        String[] result = ArrayUtils.addAll(s1, s2);
        System.out.println(Arrays.toString(result));
        int [] int1 = new int[]{1,2,3};
        int[] int2 = new int[]{4,5,6};
        int[] result2 = ArrayUtils.addAll(int1, int2);
        System.out.println(Arrays.toString(result2));
    }

输出

[a, b, c, d, e, f]
[1, 2, 3, 4, 5, 6]

Java API

纯Java API示例，支持原始类型和泛型类型。

  public static void main(String[] args) {

        String[] s1 = new String[]{"a", "b", "c"};
        String[] s2 = new String[]{"d", "e", "f"};
        String[] s3 = new String[]{"g", "h", "i"};

        String[] result = joinArrayGeneric(s1, s2, s3);

        System.out.println(Arrays.toString(result));

        int[] int1 = new int[]{1, 2, 3};
        int[] int2 = new int[]{4, 5, 6};
        int[] int3 = new int[]{7, 8, 9};

        int[] result2 = joinArray(int1, int2, int3);

        System.out.println(Arrays.toString(result2));

    }

    static <T> T[] joinArrayGeneric(T[]... arrays) {
        int length = 0;
        for (T[] array : arrays) {
            length += array.length;
        }

        //T[] result = new T[length];
        final T[] result = (T[]) Array.newInstance(arrays[0].getClass().getComponentType(), length);

        int offset = 0;
        for (T[] array : arrays) {
            System.arraycopy(array, 0, result, offset, array.length);
            offset += array.length;
        }

        return result;
    }

    static int[] joinArray(int[]... arrays) {
        int length = 0;
        for (int[] array : arrays) {
            length += array.length;
        }

        final int[] result = new int[length];

        int offset = 0;
        for (int[] array : arrays) {
            System.arraycopy(array, 0, result, offset, array.length);
            offset += array.length;
        }

        return result;
    }

输出

[a, b, c, d, e, f, g, h, i]
[1, 2, 3, 4, 5, 6, 7, 8, 9]

Java 8 Stream

Java 8 Stream连接数组的示例。

 public static void main(String[] args) {

        String[] s1 = new String[]{"a", "b", "c"};
        String[] s2 = new String[]{"d", "e", "f"};
        String[] s3 = new String[]{"g", "h", "i"};
        //join object type array
        String[] result = Stream.of(s1, s2, s3).flatMap(Stream::of).toArray(String[]::new);
        System.out.println(Arrays.toString(result));
        int [] int1 = new int[]{1,2,3};
        int[] int2 = new int[]{4,5,6};
        int[] int3 = new int[]{7,8,9};
        //join 2 primitive type array
        int[] result2 = IntStream.concat(Arrays.stream(int1), Arrays.stream(int2)).toArray();
        //join 3 primitive type array, any better idea?
        int[] result3 = IntStream.concat(Arrays.stream(int1), 
            IntStream.concat(Arrays.stream(int2), Arrays.stream(int3))).toArray();

        System.out.println(Arrays.toString(result2));

        System.out.println(Arrays.toString(result3));

    }

输出

[a, b, c, d, e, f, g, h, i]
[1, 2, 3, 4, 5, 6]
[1, 2, 3, 4, 5, 6, 7, 8, 9]

以上就是三种操作数组的方式, 如果还有别的更好的方式欢迎留言哦

欢迎留言!