JAVA: 2012

2012年8月24日星期五

Therad.join

Therad.join : 主要會完成一個程式後再跳出.

public class RunnableTest{
/**
* @param args
*/
public static void main(String[] args) {
  // TODO Auto-generated method stub
  CRTest AAA = new CRTest("AAA");
  CRTest BBB = new CRTest("BBB");

  Thread t1 = new Thread(AAA);
  Thread t2 = new Thread(BBB);

  t1.start();
  try {
   t1.join();
  } catch (InterruptedException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  t2.start();
  try {
   t2.join();
  } catch (InterruptedException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  System.out.println("end main");
}
}

public class CRTest implements Runnable{
private String id;
public CRTest(String s){
  id = s;
}

public void run() {

  for(int i = 0; i < 4; i++){
   int time = (int)(1000*Math.random());
   try {
    Thread.sleep(time);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   for(int j = 0; j < 10000000; j++);
    System.out.println(id + " is runing... Time : " + time);
  }
}
}

=====================================
AAA is runing... Time : 376
AAA is runing... Time : 46
AAA is runing... Time : 414
AAA is runing... Time : 438
BBB is runing... Time : 158
BBB is runing... Time : 801
BBB is runing... Time : 373
BBB is runing... Time : 864
end main
=====================================

sleep + random

public class CRTest implements Runnable{
private String id;
public CRTest(String s){
  id = s;
}

public void run() {

  for(int i = 0; i < 4; i++){
   int time = (int)(1000*Math.random());
   try {
    Thread.sleep(time);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   for(int j = 0; j < 10000000; j++);
    System.out.println(id + " is runing... Time : " + time);
  }
}
}

public class RunnableTest{
/**
* @param args
*/
public static void main(String[] args) {
  // TODO Auto-generated method stub
  CRTest AAA = new CRTest("AAA");
  CRTest BBB = new CRTest("BBB");

  Thread t1 = new Thread(AAA);
  Thread t2 = new Thread(BBB);

  t1.start();
  t2.start();
}
}

=======================================
AAA is runing... Time : 313
BBB is runing... Time : 671
AAA is runing... Time : 539
AAA is runing... Time : 239
AAA is runing... Time : 173
BBB is runing... Time : 628
BBB is runing... Time : 25
BBB is runing... Time : 762
========================================

Thread & Runnable

Thread
public class ThreadTest{
/**
* @param args
*/
public static void main(String[] args) {
  // TODO Auto-generated method stub
  CTest AAA = new CTest("AAA");
  CTest BBB = new CTest("BBB");
  AAA.start();
  BBB.start();
}
}

public class CTest extends Thread{

private String id;
public CTest(String s){
  id = s;
}

public void run() {

  for(int i = 0; i < 4; i++){
   for(int j = 0; j < 10000000; j++);
    System.out.println(id + " is runing...");
  }
}
}
=================================================
AAA is runing...
BBB is runing...
AAA is runing...
BBB is runing...
AAA is runing...
BBB is runing...
AAA is runing...
BBB is runing...
=================================================

Runnable

public class RunnableTest{
/**
* @param args
*/
public static void main(String[] args) {
  // TODO Auto-generated method stub
  CRTest AAA = new CRTest("AAA");
  CRTest BBB = new CRTest("BBB");

  Thread t1 = new Thread(AAA);
  Thread t2 = new Thread(BBB);
  t1.start();
  t2.start();
}
}

public class CRTest implements Runnable{
private String id;
public CRTest(String s){
  id = s;
}

public void run() {

  for(int i = 0; i < 4; i++){
   for(int j = 0; j < 10000000; j++);
    System.out.println(id + " is runing...");
  }
}
}
===================================
AAA is runing...
BBB is runing...
AAA is runing...
BBB is runing...
AAA is runing...
BBB is runing...
AAA is runing...
BBB is runing...
====================================

2012年8月22日星期三

IO Writer & Read

package kao.chih.chien.test;
import java.io.FileWriter;
import java.io.IOException;
public class WriterTest {
static String WRITER_TEST_PATH = "C:\\Test.txt";

/**
* @param args
*/
public static void main(String[] args) {
  // TODO Auto-generated method stub

   try {
    FileWriter fw = new FileWriter(WRITER_TEST_PATH,true);
    fw.write("\tHello");
    fw.close();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

}
}

package kao.chih.chien.test;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class ReadTest {
static String READ_TEST_PATH = "C:\\Test.txt";
static char data[] = new char[1024];
/**
* @param args
*/
public static void main(String[] args) {
  // TODO Auto-generated method stub
  try {
   FileReader fr = new FileReader(READ_TEST_PATH);
   int num = fr.read(data);
   String s = new String(data, 0, num);
   System.out.println(s);
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
}
}

2012年8月8日星期三

JAVA CLASS 基本架構 & 建立新的物件

建立class :
A. 建一個class需要 1. 變數 2.建構子 3.method方法.
B. class中不能在有其他class.

class 類別名稱
{
資料型態 field 名稱 ;

建構子 ()
{
...............
}

傳回值的資料型態 method 名稱 ( 引數 1, ............ )
{

}

}

建立新的物件 :
A. 宣告指向 "類別"的變數.
B. 利用new關鍵字,建立新的物件,並指派給所建立的變數.

Hello A;
A = new Hello();

也可以縮成一行

Hello A = new Hello();

2012年7月30日星期一

Eclipse SWT Project

Eclipse Installing WindowBuilder Pro

step 1.
Eclipse 安裝 WindowBuilder Pro

這裡的下載網址在:https://developers.google.com/java-dev-tools/download-wbpro?hl=zh-CN

JAVA 類別變數 & 類別方法

類別變數

類別變數可以解釋為共同變數,當一個程式用同一個class產生2個物件(A物件,B物件),當A物件改變了類別變數,B的類別變數也會跟著改變.

類別方法

類別方法是可以不用使用new一個物件,就可以使用類別方法.

class CCircle // 定義類別CCircle
{
private int num=0; // 設定num為「類別變數」
private static double pi=3.14; // 設定pi為「類別變數」
private double radius;

public CCircle(double r){ // CCircle建構元
radius=r;
num++; // 當CCircle()建構元被呼叫時，num便加1
}
public void show(){
System.out.println("area="+pi*radius*radius);
}
public static void count(){ // count() method，用來顯示目前物件建立的個數「類別方法」
System.out.println(num+" object(s) created");
}
}

public class app8_8
{
public static void main(String args[])
{
CCircle.count();
CCircle cir1=new CCircle(1.0);
cir1.count(); // 用cir1物件呼叫count() method
CCircle cir2=new CCircle(2.0);
cir1.count(); // 用cir1物件呼叫count() method
cir2.count(); // 改用cir2物件呼叫count() method
System.out.println("Math.abs(-9.9)= "+Math.abs(-9.9));
}
}

2012年7月13日星期五

JAVA 建盤輸入

import java.io.*;

public class app2_1
{
public static void main(String args[]) throws IOException
{
BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
System.out.println("請輸入數字 ");
String S1 = b.readLine();
System.out.println("輸入數字為 " + S1);
}
}

java.io
Class BufferedReader

java.lang.Object
  java.io.Reader
      java.io.BufferedReader

Direct Known Subclasses:

LineNumberReader

String readLine()
Read a line of text.

readLine

public String readLine()
                throws IOException

Read a line of text. A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed.

Returns:: A String containing the contents of the line, not including any line-termination characters, or null if the end of the stream has been reached
Throws:: IOException - If an I/O error occurs

2012年7月11日星期三

JAVA 命名規則

變數或方法從小寫字母開始
EX : myVariable

類別從大寫字母開始
EX : ShirtTest

常數識別字都常使用大寫字母和分離的字母加底線
EX : SALES_TAX

JAVA 資料型態

分類	保留字	名稱	Byte	有效範圍
整數	byte	位元組	1	-128~127
	short	智整數	2	-32,768~32,767
	int	整數	4	-2,147,483,648~2,147,483,647
	long	長整數	8	-9,223,372,036,854,775,808~ 9,223,672,036,854,775,807
浮點	float	浮點數	4	負值-3.402823E38~-1.401298E-45 正值1.401298E-45~3.402823E38
浮點	double	倍精數	8	負值-1.797693134E3.8~4.9406564584124E-324 正值4.94.6564584E-324~1.797693134862E308
其他	char	字元	2	\u0000~\Uffff
其他	boolean	布林值	2	true,false

Integer.parseInt (字串轉整數)

Integer.parseInt : 為字串轉整數

java.lang
Class Integer

java.lang.Object
  java.lang.Number
      java.lang.Integer

All Implemented Interfaces:: Serializable, Comparable<Integer>

Method Summary

static int parseInt(String s)
Parses the string argument as a signed decimal integer.

Example:

public class app1_4

{

public static void main(String args[])

{

int n1 = Integer.parseInt(args[0]);

int n2 = Integer.parseInt(args[1]);

System.out.println("n1 + n2 = " + (n1 + n2));

}

訂閱：意見 (Atom)

2012年8月24日 星期五

2012年8月22日 星期三

2012年8月8日 星期三

2012年7月30日 星期一

2012年7月13日 星期五

java.ioClass BufferedReader