Overview of collection framework
The collection framework can be understood as an array
java officially encapsulates many classes based on arrays and different data structures. These classes are collectively referred to as collection framework.
1.List table
1.1 characteristics of list table
You can precisely control the insertion position of each element in the list
Users can access elements from locations in the list and search for elements in the list
Common methods of addition, deletion, modification and query
It can be simply understood as similar to the use of arrays
1.2 # ArrayList create array
(1) Call class first
import java.util.ArrayList; import java.util.List;
(2) Create ArrayList
1. Default capacity ArrayList
public static void main(String[] args) {
List list = new ArrayList();
｝2. Customize the initial capacity List
public static void main(String[] args) {
List list = new ArrayList(6);
｝1.3 adding data to ArrayList
(1) Variable name add("data content")
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.add("java01");
}(2) Variable name Add (subscript position to add data, "data content")
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.add("java01");
list.add(3,"java002");
}1.4 # ArrayList delete data (data is automatically shifted forward)
(1) Delete the "data" # variable name in the list remove("data content")
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.remove("java01");
}(2) Deletes the subscript content # variable name at a specific location Remove (subscript position)
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.remove(2);
}
(3) After deleting the content, the return value is the deletion result
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
boolean remove = list.remove("java01");
}
1.5 # ArrayList modify data
(1) Delete the file first and add # variable name in Set (subscript position, "modified content")
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.set(2."java02");
}
1.6. ArrayList query data
(1) Query all sets #int variable name = variable name size();
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.add("java01");
int size = list.size()
}(2) get method query subscript #Object variable name = variable name get (subscript position)
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.add("java01");
Object a = list.get(1)
}(3) The first and last positions that appear do not return - 1
Subscript position where the first content appears: int variable name = variable name indexOf("content");
The subscript position of the last content: int variable name = variable name lastIndexOf("content");
(4) For loop and for each
package com.Text;
import java.util.ArrayList;
import java.util.List;
public class java001 {
public static void main(String[] args) {
List list = new ArrayList();
list.add("java01");
for (int i = 0; i < list.size(); i++) {
Object a1 = list.get(i);
System.out.println(a1);
}
for (Object a2 :list){
System.out.println(a2);
}
}2.LinkedList
2.1 # differences between LinkedList and ArrayList
ArrayList # the underlying data structure is array
The underlying data structure of Linkedlist is linked list
2.2 creation of LinkedList
Import package: import Java util. LinkedList;
LinkedList} variable name = new LinkedList();
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
}2.3 adding Linkedlis
(1) variable name add("data content")
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add("Zhang San");
}(2) Variable name Add (subscript position to add data, "data content")
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add(2，"Zhang San");
}2.4 deletion of Linkedlis
(1) delete the "data" # variable name remove("data content")
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add(2，"Zhang San");
linkedList.remove("Zhang San");
}(2) Deletes the subscript content # variable name at a specific location Remove (subscript position)
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add(2，"Zhang San");
linkedList.remove(2);
}2.5 modification of Linkedlis
(1) Delete the file first and add # variable name in Set (subscript position, "modified content")
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add(2，"Zhang San");
linkedList.set(2，"Li Si");
}2.6. Linkedlis query
(1) Query all linked lists #int variable name = variable name size();
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add(2，"Zhang San");
int size = linkedList.size();
}(2) get method query subscript #Object variable name = variable name get (subscript position)
package com.Text;
import java.util.LinkedList;
public class java002 {
public static void main(String[] args) {
LinkedList linkedList = new LinkedList();
linkedList.add(2，"Zhang San");
int size = linkedList.size();
}