Java數組的十大方法

Java數組的十大方法
以下是Java Array的前10種方法。他們是來自stackoverflow的投票最多的問題。

• 0.聲明一個數組

123String[] aArray = new String[5];
String[] bArray = {"a","b","c", "d", "e"};
String[] cArray = new String[]{"a","b","c","d","e"};

• 1.用Java打印數組

1234567int[] 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.從數組中創建一個ArrayList

1234String[] 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.檢查數組是否包含某個值

1234String[] stringArray = { "a", "b", "c", "d", "e" };
boolean b = Arrays.asList(stringArray).contains("a");
System.out.println(b);
// true

• 4.連接兩個數組

1234int[] intArray = { 1, 2, 3, 4, 5 };
int[] intArray2 = { 6, 7, 8, 9, 10 };
// Apache Commons Lang library
int[] combinedIntArray = ArrayUtils.addAll(intArray, intArray2);

• 5.內聯聲明一個數組

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

• 6.將提供的數組的元素連接成單個字符串

12345// 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.將ArrayList包含到數組中

123456String[] 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.將數組轉換為集合

123Set<String> set = new HashSet<String>(Arrays.asList(stringArray));
System.out.println(set);
//[d, e, b, c, a]

• 9.反轉一個數組

1234int[] intArray = { 1, 2, 3, 4, 5 };
ArrayUtils.reverse(intArray);
System.out.println(Arrays.toString(intArray));
//[5, 4, 3, 2, 1]

• 10.刪除數組的元素

123int[] intArray = { 1, 2, 3, 4, 5 };
int[] removed = ArrayUtils.removeElement(intArray, 3);//create a new array
System.out.println(Arrays.toString(removed));

• 再多一個 - 將int轉換為字節數組

1234byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
for (byte t : bytes) {
   System.out.format("0x%x ", t);
}

轉：https://www.programcreek.com/2013/09/top-10-methods-for-java-arrays/