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This is an Introductory course of Java Web Programming focusing on writing maintainable extensible code, methods of debugging, logging and profiling. The Java Technology used is J2EE an Enterprise Application Development tool. This lecture includes: Java, Generics, Parameterize, Errors, Compile, Time, Instantiation, Casting, Class, Interface, Stack
Typology: Slides
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generics To use generic classes and interfaces
interfaces ^ To^ declare^ generic^ classes
and^ interfaces ^ To^ understand^ why^ generic
types^ can^ improve^ reliability
and readabilityreadability To^ declare^ and^ use^ generic^ methods
and^ bounded^ generic^ types ^ To^ use^ raw^ types^ for^ backward
compatibility ^ To know wildcard types and understand why they are necessary^ To^ know^ wildcard^ types^ and
understand^ why^ they^ are^ necessary ^ To^ convert^ legacy^ code^ using
JDK^ 1.5^ generics ^ To^ understand^ that^ generic
type^ information^ is^ erased^ by
the compiler^ and^ all^ instances^ of
a^ generic^ class^ share^ the^ same
runtime p^ g class^ file To know^ certain^ restrictions^ on^ generic
types^ caused^ by^ type^ erasure ^ To^ design^ and^ implement
generic^ matrix^ classes
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^ You may be familiar with similar constructs from
^ You^ may^ be^ familiarwith^ similar^ constructs
from other^ languages,^ most
notably^ C++^ templates.
List^ myIntList =^ new^ LinkedList();
//^1 y^
() myIntList.add(new^ Integer(0));
//^2 Integer^ x^ =^ (Integer)^ myIntList.iterator().next();
//^3 docsity.com
list.add("Java^ Programming");}} }^ To understand the compileTo
understand the compilewarning on this line, you need tolearn JDK 1.5 generics.
5 learn JDK 1.5 generics.
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} }^ No compile warning on this line.
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to^ parameterize^ types.
can^ define^ a^ class^ or
a method^ with^ generic
types^ that^ can^ be^ substituted^ b^ h^ l using^ concrete^ types
by^ the^ compiler. For example, you^ may^ define^ a^ generic^
stack^ class that stores the elements of a generic type Fromthat^ stores^ the^ elements
of^ a^ generic^ type.^ From this^ generic^ class,^ you^
may^ create^ a^ stack^ object for^ holding^ strings^ and
a^ stack^ object^ for^ holdingg g j^
g numbers.^ Here,^ strings
and^ numbers^ are^ concrete types^ that^ replace^ the
generic^ type.^8
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package java.lang;
public interface Comaprable
Comparable
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+ArrayList()
java.util.ArrayList
+ArrayList()+add(o: Object) : void+add(index: int, o: Object) : void+clear(): void
+ArrayList()+add(o: E) : void+add(index: int, o: E) : void+clear(): void +clear(): void+contains(o: Object): boolean+get(index: int) : Object+indexOf(o: Object) : int
+clear(): void+contains(o: Object): boolean+get(index: int) : E+indexOf(o: Object) : int +indexOf(o: Object) : int+isEmpty(): boolean+lastIndexOf(o: Object) : int+remove(o: Object): boolean
+indexOf(o: Object) : int+isEmpty(): boolean+lastIndexOf(o: Object) : int+remove(o: Object): boolean remove(o: Object): boolean+size(): int+remove(index: int) : boolean+set(index: int, o: Object) : Object
remove(o: Object): boolean+size(): int+remove(index: int) : boolean+set(index: int, o: E) : E^11 (^ ,^ j^ )^ j^
(^ ,^ ) (a) ArrayList before JDK 1.^
(b) ArrayList in JDK 1.5docsity.com
-list: java.util.ArrayList
An array list to store elements.Creates an empty stack. +getSize(): int+peek(): E+pop(): E
Returns the number of elements in this stack.Returns the top element in this stack.p p()Returns and removes the top element in this stack. +push(o: E): E+isEmpty(): boolean
p Adds a new element to the top of this stack.Returns true if the stack is empty.
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print(E[]^ list)^ { for (int i = 0; i < list.length; i++)
<^ list.length;^ i^ ) System.out.print(list[i]^ +^ "^ ");System.out.println();}} public static void print(Object[] list) {public static void print(Object[]^ list)^ { for (int i = 0; i <^ list.length;^ i++) System.out.print(list[i]^ +^ "^ ");System.out.println();}
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