Data for container types in Java

Stingbiulder, Array, ArrayList

Stringbiulder: variable length for string only.

Array: The length of the array is fixed.

ArrayList: variable length.

Construction Method:

　　ArrayList ();

To add an element:

Public boolean Add (E E): add element

public void Add (int index,e element): Adding elements at the specified index

ArrayList (E): implementation of variable size arrays

To create a collection object:

arraylist<string> array = new arraylist<string> ();

ArrayList the additions and deletions to change:

1. Adding elements

Array.add ("Hello");

Array.add ("World");

Array.add ("Java");

2. Get elements

Public E get (int index): Returns the element at the specified index

Usage Example: Array.get (0)//run result is Hello

3. Set length

public int size (): Returns the number of elements in the collection

usage example; array.size ();//operation result is 3;

4. Deleting an element

A. Public boolean remove (Object o);//delete the specified element and return whether the deletion succeeded

Usage Example: Array.remove ("Hello");//operation result is ture;

B. public E Remove (int index);//delete the element at the specified index and return the deleted element

Usage Example: Array.remove (1);//operation result is world;

5. Modifying elements (replacing elements)

Public E Set (int index, E Element);//Modify the element at the specified index to be another element (that is, replace) and return the modified element

Usage Example: Array.set (1,android);//operation result is world;

Data for container types in Java