Top 10 Methods of Java Arrays

Top 10 Methods of Java Arrays
Here are the top 10 methods of Java Arrays. They are the most voted questions from stackoverflow.

• 0. 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. Printing 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. Create an ArrayList from the 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. 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. 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. Declare an array inline

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

• 6. Concatenates 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. Include an ArrayList into 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. Convert an Array to a Collection

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

• 9. 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. Delete elements 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);
}
```
转：https://www.programcreek.com/2013/09/top-10-methods-for-java-arrays/