0. 聲明一個數組(Declare an array)
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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. 在Java中輸出一個數組(Print an array in Java)
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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. 從數組中創建數組列表(Create an ArrayList from an array)
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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. 檢查數組中是否包含特定值(Check if an array contains a certain value)
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String[] 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( Concatenate two arrays)
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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. 聲明一個數組內鏈(Declare an array inline )
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method( new
String[]{ "a" ,
"b" , "c" ,
"d" , "e" }); |
6. 將數組元素加入到一個獨立的字符串中(Joins the elements of the provided array into a single String)
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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. 將數組列表轉換成一個數組 (Covnert an ArrayList to an array)
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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. 將數組轉換成一個集合(Convert an array to a set)
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Set<String> set =
new HashSet<String>(Arrays.asList(stringArray)); System.out.println(set); //[d, e, b, c, a] |
9. 反向數組(Reverse an array)
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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. 刪除數組元素(Remove element of an array)
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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 – convert int to byte array
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byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
for
(byte t : bytes) { System.out.format( "0x%x " , t); } |