午后星期午

          Java數(shù)組使用實用的技巧

          本文分享了關(guān)于Java數(shù)組最頂級的11大方法,幫助你解決工作流程問題,無論是運用在團隊環(huán)境或是在私人項目中,你都可以直接拿來用!

          0.  聲明一個數(shù)組(Declare an array)
           
          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(shù)組(Print an array in Java)
           
          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(shù)組中創(chuàng)建數(shù)組列表(Create an ArrayList from an array)
           
          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. 檢查愛淘寶數(shù)組中是否包含特定值(Check if an array contains a certain value)
           
          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(shù)組( Concatenate two arrays)
           
          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(shù)組內(nèi)鏈(Declare an array inline )
           
          method(new String[]{"a", "b", "c", "d", "e"});
           
          6. 將數(shù)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)

          // 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(shù)組列表轉(zhuǎn)換成一個數(shù)組 (Covnert an ArrayList to an array)
           
          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(shù)組轉(zhuǎn)換成一個集合(Convert an array to a set)
           
          Set<String> set = new HashSet<String>(Arrays.asList(stringArray));
          System.out.println(set);
          //[d, e, b, c, a]
           
          9. 反向數(shù)組(Reverse an array)
           
          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(shù)組元素(Remove element of an array)
           
          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
           
          byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();
           
          for (byte t : bytes) {
             System.out.format("0x%x ", t);
          }

          posted on 2013-12-31 14:07 午后星期午 閱讀(108) 評論(0)  編輯  收藏 所屬分類: Java

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