HashMap에 containsKey 메소드에 키값을 넘겨주면

해당 키값이 HashMap에 있을경우 true/ 없을 경우 false



HashMap에 containsValue 메소드에 값을 넘겨주면

해당 값이 HashMap에 있을경우 true/ 없을 경우 false

Map<String, String> map = new HashMap<String, String>();

map.put("A", "111");
map.put("B", "222");
map.put("C", "333");
    
System.out.println(map.containsKey("A"));
System.out.println(map.containsKey("a"));

System.out.println(map.containsValue("111"));
System.out.println(map.containsValue("AAA"));

 

결과

true
false

true
false

 

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https://www.coolsms.co.kr/download/559455 

 

https://github.com/coolsms/java-sdk/releases 

 

https://www.coolsms.co.kr/index.php?mid=SDK_Java_Getting_Started_ko 

 

https://www.coolsms.co.kr/index.php?mid=REST_API 

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DAY24 제네릭2(메소드제네릭,와일드카드)  (0) 2016.08.08

25일차 강의 정리


스레드 스케줄링

Thread.MIN_PRIORITY => 1

Thread.NORM_PRIORITY => 5

Thread.MAX_PRIORITY => 10

1~10 까지의 우선순위가 있어서, 높을 수록 실행 할 확률이 높아 진다고 보면된다.(먼저실행할 확률)

스케쥴링의 두번째로는 join()이 있어서, 우선순위로 지정한 메소드 먼저 끝낼수있게 한다.

소스1

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class Pm00 extends Thread{
    Pm00 me;
    public Pm00(String name){
        super(name);
    }
    void setMe(Pm00 me){
        this.me = me;
    }
    @Override
    public void run() {
        try{
            if(me!=null)me.join();
        }catch(InterruptedException ee){
            ee.printStackTrace();
        }
        
        for (int i = 0; i < 5; i++) {
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(this.getName()+" 스레드 순위 "+this.getPriority());        //디폴트로 5,항상동일
        }
    }
}
 
public class Ex00 {
    public static void main(String[] args) {
        Pm00 me1 = new Pm00("1번");
        Pm00 me2 = new Pm00("2번");
        Pm00 me3 = new Pm00("3번");
        
        me1.setPriority(Thread.MIN_PRIORITY);//1    //디폴트 순위는 무조건 5로시작
        me2.setPriority(Thread.NORM_PRIORITY);//5    //1(낮은순위) ~ 10(높은 순위)
        me3.setPriority(Thread.MAX_PRIORITY);//10    //우선순위를 높게주면 실행기회가높아진다
        
        me1.start();
        me2.setMe(me1);    //me1이끝날때까지 기다린다
        me2.start();
        me3.setMe(me2);    //me2이끝날때까지 기다린다
        me3.start();
 
        System.out.println("main end.");
    }
}
cs

결과1

소스2

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class Am02 implements Runnable{
    
    @Override
    public void run() {
        for (int i = 0; i < 6; i++) {
            Thread thr = Thread.currentThread();
            thr.setPriority(Thread.MIN_PRIORITY+i);
            try {
                thr.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(thr.getName()+":"+thr.getPriority());
        }
    }
}
public class Ex02 {
    public static void main(String[] args) {
        Am02 am2 = new Am02();
        
        Thread thr1 = new Thread(am2,"th1");
        Thread thr2 = new Thread(am2,"th2");
        Thread thr3 = new Thread(am2,"th3");
 
        try{
            thr1.start();
            thr1.join(100);        //( )시간동안 thr1을 실행
            thr2.start();
            thr2.join();
            thr3.start();
            thr3.join();
        }catch(InterruptedException e){
            e.printStackTrace();
        }
        System.out.println("main end");
        
    }
}
cs

결과2


동기화

소스

특정블록의 동기화

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class Bank {
    int money;
 
    public Bank() {
        money = 0;
    }
}
class ATM extends Thread{
    Bank bank;
    public ATM(Bank bank){
        this.bank = bank;
    }
    
    //특정 블록의 동기화방법
    @Override
    public void run() {
        add(1000);
        try {
            sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        del(500);
        try {
            sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        del(300);
        try {
            sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        del(200);
    }
    void add(int money){
        synchronized (bank){        //임계영역코딩(동기화할 객체 또는 동기화할 클래스명)
            this.bank.money+=money;
            System.out.println("cd입금: "+money+"원, 은행잔고: "+this.bank.money+"원");
        }
    }//add end
    synchronized void del(int money){
        synchronized (bank) {
            if (this.bank.money >= 0 && this.bank.money >= money) {
                this.bank.money -= money;
                System.out.println("cd출금: " + money + "원, 은행잔고: "
                        + this.bank.money + "원");
            } else {
                System.out.println("잔고부족");
            }
        }
    }//del end
}//ATM class end
 
public class Ex03 {
    public static void main(String[] args) {
        Bank bank = new Bank();
        ATM atm1 = new ATM(bank);
        ATM atm2 = new ATM(bank);
        ATM atm3 = new ATM(bank);
 
        System.out.println("잔고 : "+ bank.money+"원");
        atm1.start();
        atm2.start();
        atm3.start();
        try {
            atm1.join();
            atm2.join();
            atm3.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("잔고 : "+ bank.money+"원");
    }
 
}
cs

메서드 동기화

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class Bank {
    int money;
 
    public Bank() {
        money = 0;
    }
 
    // 메서드 동기화방법
      synchronized void add(int money) { 
        this.money += money;
        System.out.println("cd입금: " + money + "원, 은행잔고: " + this.money + "원");
 
    }// add end
 
    synchronized void del(int money) {
        if (this.money >= 0 && this.money >= money) {
            this.money -= money;
            System.out.println("cd출금: " + money + "원, 은행잔고: " + this.money + "원");
        } else {
            System.out.println("잔고부족");
        }
    }// del end
}
class ATM extends Thread{
    Bank bank;
    public ATM(Bank bank){
        this.bank = bank;
    }
    
    //메서드 동기화방법
     @Override
    public void run() {
        bank.add(1000);
        try {
            sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        bank.del(500);
        try {
            sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        bank.del(300);
        try {
            sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        bank.del(200);
    }
}//ATM class end
 
public class Ex03 {
    public static void main(String[] args) {
        Bank bank = new Bank();
        ATM atm1 = new ATM(bank);
        ATM atm2 = new ATM(bank);
        ATM atm3 = new ATM(bank);
 
        System.out.println("잔고 : "+ bank.money+"원");
        atm1.start();
        atm2.start();
        atm3.start();
        try {
            atm1.join();
            atm2.join();
            atm3.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("잔고 : "+ bank.money+"원");
    }
}
cs

결과

3개의 스레드가 동시에돌아도 문제없다.

소스

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class ATM2 implements Runnable{
    int money;
    
    public ATM2() {this.money=0;}
    
    @Override
    public void run() {
        add(1000);
        try {
            Thread.currentThread().sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        del(500);
        try {
            Thread.currentThread().sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        del(300);
        try {
            Thread.currentThread().sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        del(200);
    }
 
    void add(int money){
        synchronized (this) {
            this.money+=money;
            System.out.println(Thread.currentThread().getName());
            System.out.println("cd입금-"+money+"원, 은행잔고:"+this.money+"원");
        }
    }
    void del(int money){
        synchronized (this) {
            if(this.money>=0 && this.money>=money){
                this.money -=money;
                System.out.println(Thread.currentThread().getName());
                System.out.println("cd출금-"+money+"원, 은행잔고:"+this.money+"원");
            }else{
                System.out.println("잔고 부족");
            }
        }
    }
}
 
public class Ex05 {
    public static void main(String[] args) {
        ATM2 bank = new ATM2();
        System.out.println("잔고:"+bank.money+"원");
        Thread atm1 = new Thread(bank,"ATM1");
        Thread atm2 = new Thread(bank,"ATM2");
        Thread atm3 = new Thread(bank,"ATM3");
        atm1.start();
        atm2.start();
        atm3.start();
        try {
            atm1.join();
            atm2.join();
            atm3.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("잔고:"+bank.money+"원");
    }
 
}
cs

결과

*state...>?


저작자표시 비영리 변경금지

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DAY23 제네릭1  (0) 2016.08.08

24일차 강의 정리


스레드


소스1

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class Pm01 extends Thread{        //Thread 상속
    @Override
    public void run(){
        for (int i = 0; i < 6; i++) {
            try {
                Thread.sleep(1000);    //1000분의 1초 휴식->1초
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("스레드로 실행");
        }
    }
}
 
public class Ex01 {
 
    public static void main(String[] args) {
        // 스레드
        System.out.println("main start");
        Pm01 pm01 = new Pm01();
        pm01.start();        //새로운 스레드로  run()실행
        pm01 = new Pm01();    //새로운 객체
        pm01.start();        //새로운 스레드로  run()실행
        
        for (int i = 0; i < 6; i++) {
            try {
                Thread.sleep(1000);     //휴식->1초
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("main i : "+i);
        }
        System.out.println("main end");
        
    }//main end
}//class end
cs

결과1

소스2

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public class Ex02 extends Thread{
 
    public static void main(String[] args) {
        System.out.println("main start");
        Ex02 me = new Ex02();    //이객체를 통한 두번째 스레드
        me.start();                //run()이 실행
        for (int i = 0; i < 10; i++) {
            try{
                Thread.sleep(1000);
            }catch(InterruptedException e){
                e.printStackTrace();
            }
            System.out.println("main() i: "+i);
        }
        System.out.println("main end.....");
 
    }
    @Override
    public void run(){    //main 에서 실행해서 run을 스레드로 사용
        for (int i = 0; i < 10; i++) {
            try{
                Thread.sleep(1000);
            }catch(InterruptedException e){
                e.printStackTrace();
            }
            System.out.println("new Ex02 thread run() i: "+i);
        }
        System.out.println("run end...........");
    }
}
cs

결과2

소스3

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class Pm44 extends Thread{
    public Pm44(String name) {
        super(name);
    }
    @Override
    public void run() {
        for(int i=0; i<5; i++){
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(this.getName());
        }
    }
}
 
class Pm04 implements Runnable {    //인터페이스로 상속받아서 스레드 사용하기
 
    @Override
    public void run() {
        for(int i=0; i<5; i++){
            try {
                Thread.sleep(1000);        //해당 스레드를 1/1000잠시 휴식(1s)
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            Thread thr = Thread.currentThread();
            System.out.println(thr.getName());
        }
    }
    
}
 
public class Ex04 {
 
    public static void main(String[] args) {
        Pm04 pm4 = new Pm04();
        Thread thread = new Thread(pm4,"스레드 추가");        //""가 변경된 스레드 이름
        thread.start();
        Pm44 pm44 = new Pm44("상속을 통한");
        pm44.start();
        for(int i=0; i<5; i++){
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
//            System.out.println(Thread.currentThread());        //[스레드명, 스케줄링, ..?뭔단?]
            System.out.println(Thread.currentThread().getName());
        }
    }
 
}
cs

결과3



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