1. 声明一个数组
- String[] aArray = new String[5];
- String[] bArray = {"a","b","c", "d", "e"};
- String[] cArray = new String[]{"a","b","c","d","e"};
2. 输出一个数组
- 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]
3. 从一个数组创建数组列表
- 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]
4. 检查一个数组是否包含某个值 (两种方法)
- A.方法
- String[] stringArray = { "a", "b", "c", "d", "e" };
- boolean b = Arrays.asList(stringArray).contains("a");
- System.out.println(b);
- // true
- B.方法
-
String a = "b";
String [] str = new String[]{"a","b","c"};
boolean contains2 = ArrayUtils.contains(str, a);
System.out.println(contains2);
5. 连接两个数组
- int[] intArray = { 1, 2, 3, 4, 5 };
- int[] intArray2 = { 6, 7, 8, 9, 10 };
- // Apache Commons Lang library
- int[] combinedIntArray = ArrayUtils.addAll(intArray, intArray2);
6. 声明一个内联数组(Array inline)
- method(new String[]{"a", "b", "c", "d", "e"});
7. 把提供的数组元素放入一个字符串
- // 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
8. 将一个数组列表转换为数组
- 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);
9. 将一个数组转换为集(set)
- Set<String> set = new HashSet<String>(Arrays.asList(stringArray));
- System.out.println(set);
- //[d, e, b, c, a]
10. 逆向一个数组
- int[] intArray = { 1, 2, 3, 4, 5 };
- ArrayUtils.reverse(intArray);
- System.out.println(Arrays.toString(intArray));
- //[5, 4, 3, 2, 1]
11. 移除数组中的元素
- int[] intArray = { 1, 2, 3, 4, 5 };
- int[] removed = ArrayUtils.removeElement(intArray, 3);//create a new array
- System.out.println(Arrays.toString(removed));
13.计算数组相邻两个元素的差
public
class
Carray {
public
static
void
main(String[] args) {
int
[] a = {
1
,
2
,
5
,
45
,
6
,
452
,
5
};
farray(a);
}
public
static
void
farray(
int
[] a){
for
(
int
i =
0
;i < a.length-
1
;++i)
System.out.println(
"第"
+i+
"个元素与第"
+(i+
1
)+
"个元素的差为"
+(a[i]-a[i+
1
]));
}
}
- byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
- for (byte t : bytes) {
- System.out.format("0x%x ", t);
- }
-