JAVA --------
EVERYTHING IS OBJECT
OOP
class Student{
New
null
public int/void addNumber( ) throw Excepion {}
public int addNumber(int a,int b){
}
int a,int b
public
Student s=new Student()
Student Student “Student()”
()
Student s
Student
public student(string name,int a){
}
public student(int a,string name){
}
static void changename(student stu){stu.setName “LUCY”}
overloading overriding
JAVA overriding overloading
Overloading
overloading
overloading
overloading
public void teach(){};
public void teach(int a){};
public void teach(String a){}
Overloading
Byte—short—float—int—long—double
this
student(){};
student(string n){
this();// student()
}
student(int a) this(int a)
this this
This
Public void printNum(){
Int number=40
System.out.println(this.number);
}
This.number
this.number (this) number
Public
Private
private set get
this
this
11.29
SuperClass SonClass
Class Son extends Father{
}
JAVA
JAVA JAVA
overriding
overloading
public private
private
default
Protected
Public
Super() this
This()
super()
Animal a=new Dog()
Dog d=(Dog)a
Animal a=new Dog() Animal dog
Dog d=(Dog)a Dog()
instanceof
a instanceof Animal;( )
Animal
Animal true false a instanceof Animal True
a instanceof Dog True
instanceof
Instanceof
Animal a=new Animal()
Dog d=Dog()a;
Animal a=new Dog()
Animal a=getAnimal()
Public static Animal.getAnimal;
Return new Dog()
Overloading
shape circle rect
Shape zhouchang() area()
squ rect rect cha()
private public
11.29 Module6
Module6-7
static:
Static int data data
Int data
static int data;
m1.data=0;
m1.data++ 1, m2.data
Static
Public static void printData(){}
This.data
static
Static Singleton
Singleton 11.30
final
final final final
final
JAVA final JAVA
Final int AGE=10
Final static
Static final int age=10
JAVA public static final
final
Final int x=3
final
Public final void print(){}
final
final
private static final private static final
final private default protected public
Abstract(
abstract
Abstract
Final abstract
abstract
private void print(){}
Abstract void print()
abstract
Abstract static static abstract
\CODING\abstract\TestClass.java
public class TestClass{
public static void main(String[] args){
SuperClass sc=new SubClass();
Sc.print();
}
Abstract class SuperClass{
Abstract void print();}
}
class SubClass extends SuperClass(){
void print(){
System.out.println(“print”);}
}
JAVA interface
:
interface IA{
public interface
public
public public
class IAImple implements IA{
};
public public
public
class IAImpl extends java.util.Arrylist implement IA{}
Implements IA,IB
interface IC extends IA,IB{};
IA I=new IAImpl();
IAImple extends A implement IA,IB
IB I=new IAImple();
I instance of IAImple;
I instance of A;
I instance of IA;
I instance of IB;
true.
JAVA
XX
JAVA JDBC
JAVA Object JAVA
Object:
(1)finalize
(2)toString():
toString()
toString() toString()
toString()
(3)equal
String A=new String(“hello”);
String A=new String(“hello”);
A==B( FALSE)
AB
JAVA String final JAVA VM String a=”hello” NEW ”hello” ”hello” ”hello” String b=”hello” “hello”
String a=”hello”;
System.out.println(a==”hello”);
true
equal: System.out.println(a.equal(b));
equal
a.equal(b)
student a=new student(“LUCY”,20);
student b=new student(“LUCY”,20);
System.out.println(a.equal(b));
false
equal ture false
public boolean equals(Object o){
student s=(student)o;
if (https://www.doczj.com/doc/329262714.html,.equals(https://www.doczj.com/doc/329262714.html,)&&s.age==this.age)
else return false;
equals()
equals
public boolean equals(Object o){
if (this==o) return trun; //
if (o==null) return false;
if (! o instanceof strudent) return false; //
studeng s=(student)o; //
if (https://www.doczj.com/doc/329262714.html,.equals(https://www.doczj.com/doc/329262714.html,)&&s.age==this.age) return true;
else return false;
}
equals
employee String name,int id,double salary. get set toString equals
JAVA Object int char
int I=10;
String s=I+” ”;
String s1=String.valueOf(i);
Int I=10;
Interger I_class=new integer(I);
javadoc
“==”
JDK JDK JDK
double\interger\string
12.01
PROTECTED PRIVATE PUBLIC DEFAULT
this.
.this.
PRIVATE
private
outer inner outer.class outer$inner.class
TestOuter.java class.
out.inner.
inner s=new inner(); inner
new
Outer.Inner in=Outer.new.Inner()
Outer.Inner in=new Outer.Inner()
Outer private
public private
final
static
new
Outer.Inner in=new Outer.Inner()
private
People
{
run();
}
Machine{
run();
}
robot
class Robot extends People implement Machine.
run()
IA
IA I=new IA(){};
new
Out$1.class
Exception MODEL7
JAVA Throwable
Throwable Error Exception
Error
Error Throwable Exception
Exception Runtime exception
Runtime exception
Exception
throw
throws try
JDK throw
public void print() throws Exception.
throws Exception
throw new Exception() JAVA
try……catch
try { } catch(exception e){ }
exception exception exception catch
Try try catch try
try catch try catch catch exception excepiton JAVA
try catch finally finally
exception
try catch
API
Exception message catch
Catch(IOException e){System.out.println(e.message())};
Catch(IOException e){e.printStackTrace()};
try try
throw( try catch
try catch
excepiton RuntimeException Throw
throws Throws
assert
assert
Assert assert
throws throws try catch
int add(int a,int b)
{
return a+b
}
a+b=100; 100
12.02
API
java.util.* NEW
JAVA1.5 JAVA1.4
collection map
Collection Map
List Set SortedMap
SortedSet
JAVA
Collection
List List
Set List
SortedSet
Map Key-Value Key-Value key value key value
key1—value1;
key2—value2;
key3—value3.
SortedMap Map key SortedMap
List ArrayList LinkedList
ArrayList ArrayList ArrayList
ArrayList add(Object o)
ArrayList
import java.util.*
ArrayList
ArrayList
List get size Set
Collection Iterator() Set List
Iterator it=c.iterator(); interator Interator hasNext() True next Next()
Collections static
Sort List
Collections.Sort()
Sort
https://www.doczj.com/doc/329262714.html,ng Comparable
comparableTo(Object o)
int
>o >0
=o =0
TestArraylist java -1 java.util Comparator( ) compare() Sort Sort List,List(Compate) comparTo() implement comparable. EMPLOYEE ArrayList Iterator JAVA1.5 LinkedList ArrayList ArrayList object ArrayList LinkedList LinkedList ArrayList LinkedList LinkedList LinkedList ArrayList addFirst(); removeFirst(); addLast(); removeLast(); push pop Push addFirst() pop removeFirst() isEmpty()-- put get Put addFirst() get removeLast() List Vector ArrayList Vector Vector ArrayList java.util.stack stack Vector stack Vector Vector Vector get push get Stack LinkedList JAVA1.5 collection queue Set-HashSet HashSet Object final() toString() equals() hashCode() HashSet add(Object o) hashCode int hc=o.hashCode(); hashCode Int I=hc%n; I=0 a[0] I=1, a[1] equals() true equals() false hashCode hashcode equals() student hashcode String String string JDK hashCode hashSet hashcode() equals() hashcode equals() True equals() hashCode equals() hashCode hashCode hashCode public int hashCode(){ return name.hashcode()+age; } hashCode hashSet hashSet hashCode hashSet hashSet HashSet hashSet new hashset employee Student S Al.add(s); s.setName(“lucy”); s2 12.05 SortedSet SortedSet TreeSet: TreeSet TreeSet HashSet TreeSet HashCode() equals() compareable compareTo() HashSet CompareTo() Set Map key value ArrayList HashSet HashMap ArrayList HashMap HashMap put() get() Map keySet() set keySet() key put() value Set s=m.keySet(); Interator it=new interator(); Object key=it.next(); Object value=m.get(key); HashMap HashCode Sort HashMap key value Key m.put(new sutdent(“Liucy”,30),”boss”) Student key HashCode() equals() HashMap HashSet HashMap HashSet HashMap API HashSet (key.null) HashMap key value TreeSet TreeMap TreeSet TreeMap ——
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