進階應用程式設計 2014/12/07

進階程式設計⺩王哲輝

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Hi, I’m Samael

Pr. Engineer, Connected Services, HTC Creative Labs

[email protected]

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課程規劃

⼀一個⺫⽬目標

兩個主題

三個週次

⺫⽬目標

⺫⽬目標

沒有⼈人睡著

⺫⽬目標對 Java ⾏行動裝置程式設計

⺫⽬目標對 Java ⾏行動裝置程式設計

略懂~略懂~

主題

Java 物件與執⾏行緒

Android 基本概念

主題

Java 物件與執⾏行緒

Android 基本概念這部份⽤用 C/C++ 解釋

週次W1: Java 物件與執⾏行序

W2: Android 基本概念

W3: Android (續) + 專案展⽰示(暫定)

範例程式

https://github.com/freesamael/npu-java-course-2014-fall

https://github.com/freesamael/npu-java-course-2014-fall

學 Java 到底可以幹嘛?

藍鑽級程式設計師

Java 平台

Java EE Java SE Java ME

Android

Java EE

Java EE很夯的雲端

Java EE很夯的雲端

https://www.youtube.com/watch?v=vxf1skKXwM0

千⾔言萬語不如看廣告

Java SE

Java SE

Java

Java ME

Java ME

Series 40

Java ME⼀一代霸主

Series 40

Java ME⼀一代霸主

過氣英雄Series 40

Java ME

東⼭山再起

Java ME

東⼭山再起進廣告

https://www.youtube.com/watch?v=Kt5VulFqBm4

Android

“Java 是⼀一種物件導向程式語⾔言”

什麼是物件?

將真實世界的物件對應到程式語⾔言

典型範例

以 C 實作資料結構#define FF (0)#define FR (1)#define RR (2)

struct Porche911 {int cost;int top_speed;double time_0_62;double braking_distance;double cornering;int layout;double speed;double position;

};

初始化

void init911(struct Porche911 *p911) {p911->cost = 172700;p911->top_speed = 311;p911->time_0_62 = 4.0;p911->braking_distance = 30.2;p911->cornering = 0.99;p911->layout = RR;

p911->speed = 0.0;p911->position = 0.0;

}

油⾨門 / 煞⾞車

void accelerate(struct Porche911 *p911, double depth, double duration) {

p911->speed = ...p911->position = ...

}

void brake(struct Porche911 *p911, double depth, double duration) {

p911->speed = ...p911->position = ...

}

C++ 的作法class Porche911 {public:

Porche911();void accelerate(double depth, double duration);void brake(double depth, double duration);

private:int cost;int top_speed;double time_0_62;double braking_distance;double cornering;int layout;double speed;double position;

};

流程⽐比較

int main(int argc, char *argv[]) {struct Porche911 my911;init911(&my911);accelerate(&my911, 0.8, 1.2);brake(&my911, 0.3, 0.5);return 0;

}

int main(int argc, char *argv[]) {Porche911 my911;my911.accelerate(0.8, 1.2);my911.brake(0.3, 0.5);return 0;

}

Object = data + code

Object = data + code

也就是封裝

什麼是物件導向?

封裝、繼承、多型

繼承

Generalization

Specialization

A Sedan is-a Vehicle A SUV is-a Vehicle A MPV is-a Vehicle

class Point2d {public:

int x;int y;

};

class Point3d : public Point2d {public:

int z;};

Q1 - 輸出?#include <cstdio>int main(int argc, char *argv[]) {

Point2d p2d;p2d.x = 100;p2d.y = 50;printf("Point2d: x=%d, y=%d\n", p2d.x, p2d.y);

Point3d p3d;p3d.x = 100;p3d.y = 50;p3d.z = 75;printf("Point3d: x=%d, y=%d, z=%d\n", p3d.x, p3d.y, p3d.z);

Point2d *p2dp = &p3d;p2dp->x = 50;p2dp->y = 100;printf("pointer of Point3d as Point2d: x=%d, y=%d\n",

p2dp->x, p2dp->y);

return 0;}

Q2 - 以 C 語⾔言改寫

class Point2d {public:

int x;int y;

};

class Point3d : public Point2d {public:

int z;};

struct Point2d {int x;int y;

};

struct Point3d {struct Point2d base;int z;

};

Q3 - 輸出?#include <stdio.h>int main(int argc, char *argv[]) {

struct Point2d p2d;p2d.x = 100;p2d.y = 50;printf("Point2d: x=%d, y=%d\n", p2d.x, p2d.y);

struct Point3d p3d;p3d.base.x = 100;p3d.base.y = 50;p3d.z = 75;printf("Point3d: x=%d, y=%d, z=%d\n", p3d.base.x, p3d.base.y, p3d.z);

struct Point2d *p2dp = (struct Point2d *)&p3d;p2dp->x = 50;p2dp->y = 100;printf("pointer of Point3d as Point2d: x=%d, y=%d\n",

p2dp->x, p2dp->y);

return 0;}

多型

class Engineer {const char *title;

public:Engineer(): title("Engineer") {}const char* getTitle() {

return title;}

};

class SrEngineer : public Engineer {const char *title;

public:SrEngineer(): title("Sr. Engineer") {}const char* getTitle() {

return title;}

};

class PrEngineer : public Engineer {const char *title;

public:PrEngineer(): title("Pr. Engineer") {}const char* getTitle() {

return title;}

};

Q4 - 輸出?

#include <cstdio>int main(int argc, char *argv[]) {

Engineer eng;printf("%s\n", eng.getTitle());SrEngineer sr;printf("%s\n", sr.getTitle());PrEngineer pr;printf("%s\n", pr.getTitle());

return 0;}


Engineer eng;SrEngineer sr;PrEngineer pr;

Engineer *engp = &eng;printf("%s\n", engp->getTitle());engp = &sr;printf("%s\n", engp->getTitle());engp = &pr;printf("%s\n", engp->getTitle());

return 0;}

class Engineer {const char *title;

public:Engineer(): title("Engineer") {}virtual const char* getTitle() {

return title;}

};

class SrEngineer : public Engineer {const char *title;

public:SrEngineer(): title("Sr. Engineer") {}const char* getTitle() {

return title;}

};

class PrEngineer : public Engineer {const char *title;

public:PrEngineer(): title("Pr. Engineer") {}const char* getTitle() {

return title;}

};


Engineer eng;SrEngineer sr;PrEngineer pr;

Engineer *engp = &eng;printf("%s\n", engp->getTitle());engp = &sr;printf("%s\n", engp->getTitle());engp = &pr;printf("%s\n", engp->getTitle());

return 0;}

Q7 - 以 C 語⾔言改寫class Engineer {

const char *title;public:

Engineer(): title("Engineer") {}const char* getTitle() {

return title;}

};


Engineer eng;printf("%s\n", eng.getTitle());

return 0;}

struct Engineer {const char *title;

};

void Engineer_init(struct Engineer *this) {this->title = "Engineer";

}

const char* Engineer_getTitle(struct Engineer *this) {return this->title;

}

#include <stdio.h>int main(int argc, char *argv[]) {

struct Engineer eng;Engineer_init(&eng);printf("%s\n", Engineer_getTitle(&eng));

return 0;}

這個也可以⽤用 C 語⾔言改寫嗎?class Engineer {

const char *title;public:

Engineer(): title("Engineer") {}virtual const char* getTitle() {

return title;}

};


Engineer eng;printf("%s\n", eng.getTitle());

return 0;}

中場休息 Q&A

Java 執⾏行緒

GUI 範例

Start a Thread #1

public class HelloRunnable implements Runnable {

public void run() { System.out.println("Hello from a thread!"); }

public static void main(String args[]) { (new Thread(new HelloRunnable())).start(); }

}

Start a Thread #2

public class HelloThread extends Thread {


public static void main(String args[]) { Thread t = new HelloThread(); t.start(); }

}

Sleeppublic class HelloThread extends Thread {

public void run() { try { Thread.sleep(4000); } catch (InterruptedException e) {} System.out.println("Hello from a thread!"); }

public static void main(String args[]) { Thread t = new HelloThread(); t.start(); }

}

Joinpublic class HelloThread extends Thread {


public static void main(String args[]) { Thread t = new HelloThread(); t.start(); try { t.join(); } catch (InterruptedException e) {} }

}

回顧 GUI 範例

Q8 - 輸出?

public class Counter { private int c = 0;

public void increment() { c++; }

public void decrement() { c--; }

public int value() { return c; }}

public static void main(String args[]) {final Counter c = new Counter();

Thread t1 = new Thread() {public void run() {

for (int i = 0; i < 50000; i++) c.increment();}

};

Thread t2 = new Thread() {public void run() { for (int i = 0; i < 50000; i++)

c.decrement();}

};

t1.start();t2.start();try {

t1.join();t2.join();

} catch (InterruptedException e) {}

System.out.println("value=" + c.value());}

臨界區段 (Critical Section)

Critical Section 要件

• Mutual Exclusion：不允許兩個以上的執⾏行緒同時在對應的 critical section 中執⾏行。

• Progress：若沒有執⾏行緒在對應的 critical section 中執⾏行，則控制的機制不能阻擋請求進⼊入 critical section 之執⾏行緒進⼊入critical section。

• Bounded Waiting：控制機制必須使等待進⼊入 critical section 之執⾏行緒在有限時間內得以進⼊入。

三種做法

• Semaphore

• Mutex (= binary semaphore)

• Monitor

• Message Passing

三種做法

• Semaphore

• Mutex (= binary semaphore)

• Monitor

• Message Passing

全部講下去就要花三週了...

Synchronizationpublic class SynchronizedCounter { private int c = 0;

public synchronized void increment() { c++; }

public synchronized void decrement() { c--; }

public synchronized int value() { return c; }}

Q9 - does it work?public class SynchronizedCounter { private int c = 0;

public synchronized void increment() { c+=2; decrement(); }

public synchronized void decrement() { c--; }

public synchronized int value() { return c; }}

Reentrant Synchronization

⼀一個執⾏行緒不能 acquire 其他執⾏行緒正在使⽤用的 lock，但是可以重複 acquire 已經取得的 lock。

Reentrant Synchronization

⼀一個執⾏行緒不能 acquire 其他執⾏行緒正在使⽤用的 lock，但是可以重複 acquire 已經取得的 lock。

換個說法：已經進⼊入 critical section 內的執⾏行緒可以持續執⾏行相同 critical section 的功能。

Deadlock static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s" + " has bowed to me!%n", this.name, bower.getName()); bower.bowBack(this); } public synchronized void bowBack(Friend bower) { System.out.format("%s: %s" + " has bowed back to me!%n", this.name, bower.getName()); } }

Deadlock

public static void main(String[] args) { final Friend alphonse = new Friend("Alphonse"); final Friend gaston = new Friend("Gaston"); new Thread(new Runnable() { public void run() { alphonse.bow(gaston); } }).start(); new Thread(new Runnable() { public void run() { gaston.bow(alphonse); } }).start(); }

Java Monitor(Optional)

Producer Consumer Problem

(Optional)

作業撰寫⼀一 Java 程式，由命令列輸⼊入兩個 4x4 矩陣 A、B，以 4 個背景執⾏行緒平均執⾏行 A x B 矩陣相乘之運算，

從命令列印出運算結果。

Deadline: 12/20

參考此網站驗證結果 http://www.bluebit.gr/matrix-calculator/

matrix_multiplication.aspx

http://www.bluebit.gr/matrix-calculator/matrix_multiplication.aspx

進階應用程式設計 2014/12/07

Engineering