10 một số lớp cơ sở trong java

7/31/2019 10 Mt s lp c s trong java

1/28

Mt s lp c s


2/28

Mt s lp c s 2Nguyn Vit H

Ni dung

Cc lp d liu nguyn thy Xu k t

Lp Math

Mng

Cc lp Container


3/28


Ti liu tham kho

Bruce Eckel, Thinking in Java, chapter 11 Deitel, Java How to program, chapter 7,

11, 20

on Vn Ban, Lp trnh hngi tngvi Java, NXB Khoa hc k thut, chng6.


4/28


Mt s lp c bn

Object

Boolean Character Void Number Math String StringBuffer

IntegerShortByte Long Float Double

...


5/28


Lp Object

Class getClass(): tr li tn lp cai tng hin thi.

boolean equals(Object): so snh i

tng, thng c nh ngha li. String toString(): tr li biu din

vn bn ca i tng, thng c nhngha li.


6/28


Person p = new Person(John);

Class c = p.getClass();

System.out.println(c);

----

class Person


7/28


Cc lp d liu nguyn thy

Cc phng thc tin chvalueOf(String s): tr i tng thuc

kiu tng ngtypeValue(): tr gi tr nguyn thy tng

ngstatic parseType(String s): tr gi tr

nguyn thy tng ng

Hng sType.MAX_VALUE, Type.MIN_VALUE


8/28


Lp Character

Cc phng thc static boolean isUppercase(char ch)

static boolean isLowercase(char ch)

static boolean isDigit(char ch)

static boolean isLetter(char ch)

static boolean isLetterOrDigit(char ch)

static char toUpperCase(char ch)

static char toLowerCase(char ch)


9/28


Lp String

Xu k t khng thay i c ni dung Khi toString(String),

String(StringBuffer)

String(byte[]), String(char[])

Phng thcint length(): kch thc ca xu

char charAt(int index): k t v trindex


10/28


Lp String

So snh

boolean equals(String)

boolean equalsIgnoreCase(String)

boolean startWith(String)boolean endWith(String)

int compareTo(String)


11/28


12/28


Lp String

Tm kimint indexOf(char), int

indexOf(char ch, int from)

int indexOf(String), int

indexOf(String s, int from)

int lastIndexOf(char),

lastIndexOf(char, int)

lastIndexOf(String),lastIndexOf(String, int)


13/28


Lp String

Thay thString replace(char ch, char

new_ch)

Trch xuString trim(): loi b k t trng

String substring(int startIndex)

String substring(int startIdx, int

endIdx)


14/28


Lp StringBuffer

Xu k t thay i c ni dung Khi to

StringBuffer(String)

StringBuffer(int length)

StringBuffer(): t kch thc mc nh 16 Cc phng thc

int length(), void setLength()

char charAt(int index)

void setCharAt(int index, char ch)

String toString()


15/28


Lp StringBuffer

Thm, xaappend(String), append(type)

insert(int offset, String s),

insert(int offset, char[] chs),

insert(int offset, type t)

delete(int start, int end): xa xucon

delete(int index): xa mt k treverse(): o ngc


16/28


Lp Math

Hng sMath.EMath.PI

Cc phng thc static type abs(type)

double ceil(double), double floor(double)

int round(float), long round(double)

type max(type, type), type min(type, type)

double random(): sinh s ngu nhin trong on

[0.0,1.0]


17/28


Lp Math

Ly tha double pow(double, double)

double exp(double)

double log(double)

double sqrt(double)

Lng gic double sin(double)

double cos(double)

double tan(double)


18/28


Mng Mng l i tng

cha mt tp cc i tng khc

cn to ra trc khi s dng (new)

V d:int a[];

a = new int[10];

for (int i=0; i


19/28


Truyn tham s v nhn gi tr tr li

int[] myCopy(int[] a) {

int b[] = new int[a.length];

for (i=0; i


20/28


Mng nhiu chiuint a[][];

a = new int[10][20];

a[2][3] = 10;

for (int i=0; i


21/28


Copy mng

System.arraycopy(src, s_off,

des, d_off, len)

src: mng ngun, s_off: offset ca mng

ngundes: mng ch, d_off: offset ca mng ch

len: s phn t cn copy

Copy ni dung ca d liu nguyn thy,copy tham chiu i vi i tng


22/28


Lp Arrays

Nm trong gi java.util

Cung cp 4 phng thc static lmvic vi mngfill(): khi to cc phn t ca mng vi

mt gi tr nh nhausort(): xp xp mngequals(): so snh hai mngbinarySearch(): tm kim nh phn trn

mng sp xp


23/28


So snh mng equals()

So snh mng d liu nguyn thy Gi phng thc equals() so snh mng

i tng

----

int a[] = { 1, 3 , 2 , 4 };

int b[] = new int[a.length];

System.arraycopy(a,0,b,0,a.length);

System.out.println(Arrays.equals(a,b));


24/28


Sp xp mng sort()

Lm vic vi cc mng d liu nguynthy

Lm vic vi cc lp i tng c ci t

giao din Comparablephng thc compareTo()


25/28


Cc lp tuyn tp (Container)

Tree Map

HashSet >

Sorted SetArray List Vector LinkedList

>

Map

>

Sorted Map

>

List

HashMap

HashTable

>

Set

Tree Set

>

Collection


26/28


Iterator

Mu dng duyt cc phn t ca mttp hp

L mt interface trong Java:

hasNext()next()

remove()

Cc lp Collection ci t Iterator


27/28


import java.util.*;

public class TestList {

static public void main(String args[]) {

Collection list = new LinkedList();

list.add(3);

list.add(2);

list.add(1);

list.add(0);

list.add(happy new year!");

Iterator i = list.iterator();

while (i.hasNext()) {

System.out.println(i.next());

}

}

}


28/28


import java.util.*;

public class Test {

static public void main(String args[]) {

List list = new LinkedList();

list.add(3);

list.add(2);

list.add(1);

list.add(0);

list.add("go!");

for (int i=0; i

10 một số lớp cơ sở trong java

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