Java 數組的 12 個最佳方法

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1.  聲明一個數組

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

2.  輸出一個數組

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

3.  從一個數組建立數組列表

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.  檢查一個數組是否包含某個值

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

5.  串連兩個數組

    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.  聲明一個內聯數組（Array inline）

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

7.  把提供的數組元素放入一個字串

    // 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.  將一個數組列錶轉換為數組

    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.  將一個數群組轉換為集（set）

 

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

10.  逆向一個數組

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

11.  移除數組中的元素

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

12.  將整數轉換為位元組數組

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

 

Java 數組的 12 個最佳方法