Java Programs

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Java Programs

• Examples 11 to 15

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Index

• 11. Rotate vector - rotate.java
• 12. Threads - bouncer.java
• 13. Network - client.jav
• 14. Network - nrserv.jav
• 15. Grahics - plot.java
• 16. Genetic algorithm - ga2.java
• GA description in separate doc

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Example 12

• Thread demo bouncer.java
• Class Ball extends Thread
• Init adds buttons
• Event handler makes balls
• Start is a lib method of thread
• ball.start() works with run()
• Graphics g getGraphics()

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Example 12 continued

• ball new Ball(g) makes balls
• Draw circle - g.filloval(x,y, dia, dia )
• Boolean - keepgoing
• Starts or stops just the last ball
• Display size rectRightX
• Only last ball can be stopped

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Example 13 background

• Iterative function - Newton Raphson
• Used to calculate a square root
• estnew is a native float
• estnew (estold Value/estold)/2
• Sqr root (Value is 100) 10
• Final answer 10
• Initial estimate - estold 1000

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Example 13 bgnd cont.

• estnew (estold Value/estold)/2
• estnew (1000100/1000)/2500
• estnew (500100/500)/2250 etc
• Calc needs estold and Value
• During run client sends strings
• Text command - run Value est
• nrserv sends back - ansnew

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Example 13 client.java

• Network client.java
• Works with nsrerv.java
• Uses sockets
• Input stream inpstr
• Output stream outstr
• sock new Socket
• (157.228.x.x, 4444)

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Example 13 continued.

• Server makes all calculations
• Outval 100
• Outstr.println(outval)
• Iterate - ansoldansnew
• Edit IP address connect to server
• Command ipconfig/all or use wincfg
• Answer is printed on screen

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Example 14 nrserv.java

• Server accepts sock when
• Client connects
• Worker thread created
• class Worker extends Thread
• new Worker( sock ).start()
• Method run() is invoked
• Remember inputs to server - strings

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Example 14 continued

• To read string convert to integer
• valstrg inpstr.readline()
• Value Integer.parseInt(valstrg)
• Wrapper classes
• Lower case float normal native float
• Upper case Float denotes
• Special class/object with methods wrapped around

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Example 14 continued

• To read and convert string to float
• Float temp Float.valueOf(eststrg)
• float estold temp.floatValue()
• This is special feature of Java
• Input - Ctrlstrg valstrg eststrg
• Uses ctrlstrg - Value(int) - estold(float)
• Output value for client estout

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Example 15 plot.java

• A prototype graph plotting program
• Normalised device coordinates NDC
• All methods use g, xMAX, yMAX
• Improved version 2 uses graph object and set
  graphics method
• Polyline draws more than one line to produce a
  curve

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Example 15 plot.java cont.

• Operations
• Draw a border
• Get min, max and range for arrays
• Normalise arrays
• Scale arrays
• Translates arrays
• Plots graph using polyline

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Example 15 plot.java cont.

• Marks title and axes
• Marks points on graph
• Ver 2 plotgrafs uses
• Normalised graphics class NormG
• GraphObj class - model class
• Ver 3 gplot
• show how to creates three
• graph instances