List in set (2)

Catalog

One 、List frame

Two 、List Common methods in

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One 、List frame

/----Collection Interface ： Single column set , Objects used to store one by one 
    /----List Interface ： Stored in order , Repeatable data （ The dynamic array ）     Used to replace the original array 
        /----ArrayList： As List The main implementation class of the interface , Threads are not safe , Efficient , Bottom use Object[] elementDate Storage 
        /----LinkedList: For frequent inserts 、 Delete operation , Efficient than ArrayList higher , The bottom layer uses a double linked list 
        /----Vector： As List The old implementation class of the interface , Thread safety , Low efficiency , Bottom use Object[] elementDate Storage 

Two 、List Common methods in

void add(int index, object ele): stay index Position insert ele Elements 
boolean addAlL(int index, collection eles): from index The position will begin eLes Add all the elements in 
object get(int index)∶ Get specified index The element of location 
int indexof(object obj): return obj The first place in the set 
int lastIndexof(object obj): return obj The last position in the current set 
object remove(int index): Remove the specified index The element of location , And return this element 
object set(int index,objectele): Set the specified index The element of position is eLe
List sublist(int fromIndex, int toIndex): Return from fromIndex To toIndex Subsets of positions 

 summary : Common methods 
 increase : add(object obj)
 Delete : remove(int index) / remove(0bject obj)
 Change : set(int index, object ele)
 check : get(int index)
 insert : add(int index,object ele)
 length :size()
 Traverse :Iterator Iterator mode ： First use iterator() Generate something like a pointer ,while（iterator.hasNext){ Output next()}
     enhance for loop ：for( type   local variable : The array or collection to traverse ）
     The normal cycle ： combination get Method 

public class ListTest {
    @Test
    public void test() {
        ArrayList list = new ArrayList();
        list.add(123);
        list.add(345);
        list.add("aa");
        list.add(new Person(12, "tom"));

        List integers = Arrays.asList(1, 23, 4);
        list.add(integers);//[123, 345, aa, Person{age=12, name='tom'}, [1, 23, 4]]
        // It's on it addAll Words ,1,23,4 Three data 
        System.out.println(list);
    }
}