java基础-数组（二）

原文地址：http://www.longluo.me/blog/2016/08/06/Top-10-Methods-For-Java-Arrays/

 

0. 声明一个数组

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String[] aArray = new String[5]; String[] bArray = {"a","b","c", "d", "e"}; String[] cArray = new String[]{"a","b","c","d","e"};

1. 打印数组

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int[] intArray = { 1, 2, 3, 4, 5 }; String intArrayString = Arrays.toString(intArray); // print directly will print reference value System.out.println(intArray); // [I@7150bd4d System.out.println(intArrayString); // [1, 2, 3, 4, 5]

2. 从一个数组中创建一个ArrayList

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String[] stringArray = { "a", "b", "c", "d", "e" }; ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray)); System.out.println(arrayList); // [a, b, c, d, e]

3. 判断数组中是否包含一个特定的值

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String[] stringArray = { "a", "b", "c", "d", "e" }; boolean b = Arrays.asList(stringArray).contains("a"); System.out.println(b); // true

4. 连接2个数组

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int[] intArray = { 1, 2, 3, 4, 5 }; int[] intArray2 = { 6, 7, 8, 9, 10 }; // Apache Commons Lang library int[] combinedIntArray = ArrayUtils.addAll(intArray, intArray2);

5. 声明一个inline数组

1	method(new String[]{"a", "b", "c", "d", "e"});

6. 将一个数组中元素变成一个字符串

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// containing the provided list of elements // Apache common lang String j = StringUtils.join(new String[] { "a", "b", "c" }, ", "); System.out.println(j); // a, b, c

7. 将一个ArrayList转换成一个数组

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String[] stringArray = { "a", "b", "c", "d", "e" }; ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray)); String[] stringArr = new String[arrayList.size()]; arrayList.toArray(stringArr); for (String s : stringArr) System.out.println(s);

8. 将一个数组转换成一个Set

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Set<String> set = new HashSet<String>(Arrays.asList(stringArray)); System.out.println(set); //[d, e, b, c, a]

9. 反转一个数组

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int[] intArray = { 1, 2, 3, 4, 5 }; ArrayUtils.reverse(intArray); System.out.println(Arrays.toString(intArray)); //[5, 4, 3, 2, 1]

10. 从一个数组中删除一个单元

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int[] intArray = { 1, 2, 3, 4, 5 }; int[] removed = ArrayUtils.removeElement(intArray, 3);//create a new array System.out.println(Arrays.toString(removed));

One more - 将int转换成一个byte array

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byte[] bytes = ByteBuffer.allocate(4).putInt(8).array(); for (byte t : bytes) { System.out.format("0x%x ", t); }

以上！