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E:\java-unix>java Test
Arne: 3 * 4 er:12
E:\java-unix>javac Test.java
Kjøring:
}
protected int xx (int i)
{ return i*3;}
public class Test
{
public static void main (String [ ] args )
{
test am = new Test( );
System.out.println("Arne: 3 * 4 er:" + am.xx(4) );
}
//Fil: Test.java
import java.io.*;
Kildefil: Test.java (ant. byte: 247)
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System.out.print(”Gi neste tall:”);
System.out.flush();
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<applet
code=Applet1
width=500
height=200>
</applet>
Tilhørende lagt inn på en ’html-side’(fil: xyz.html):
public class Applet1 extends Applet {
public void paint(Graphics g) {
g.drawString("Arnes første applett", 10,
10);
}
}
import java.awt.*;
import java.applet.*;
//App1et1.java
Applet -eksempel
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public static void main
( String[] args)
{
int i = 0;
biltest b = new biltest( );
b.make_queue( );
}
public class biltest{
Bil first = new Bil( );
Bil sist = first;
Bil refA;
class Bil{
Bil neste ;
int reg_nr = 0;
}
// fil: biltest.java
import java.io.*;
24
Kjøring:
E:\Sun-NT-Java\PC-Java>java biltest
Start test
Slutt test, antall biler er : 1001
} //
}
for (i= 1; i <= 1000; i++){
refA = new Bil( );
sist.neste = refA;
sist = sist.neste;
}
System.out.println
("Slutt test, antall biler er : ” + i);
void make_queue ( )
{ int i;
System.out.println("Start test");
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public static void main
( String[ ] args){
new astest( ).test( );}
// array av string-pekere
String [ ] sa;
public class astest{
int [ ] a = new int [100];
Bil [ ] b = new Bil [14];
String s1 =”Hei, hei”;
class Bil{
Bil neste ;
int reg_nr = 0;
}
// fil: astest.java
import java.io.*;
}
} //
26
if ( sa[0] != null) System.out.
println(“sa[0].length( ) = “ + sa[0].length( ) );
else System.out.println(“Null-peker”);
System.out.println("a.length = “ + a.length );
System.out.println("b.length = “ + b.length );
System.out.println(“s1=” + s1+ ",
s1.length ( ) = “ + s1.length( ));
sa = new String [17];
System.out.println("sa.length = “ + sa.length );
System.out.println(“sa[0]=” + sa[0] );
void test( ) {
for (int i = 0; i < b.length ; i++)
b[i] = new Bil();
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©Arne Maus, aug. 1999
E:\Sun-NT-Java\PC-Java>
E:\Sun-NT-Java\PC-Java>java astest
a.length = 100
b.length = 14
s1=Hei, hei, s1.length() = 8
sa.length = 17
sa[0]=null
Null-peker
27
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2019 Dec 17 13:30 AllNames.html
1438 Dec 17 13:30 astest.html
463 Dec 17 13:30 packages.html
464 Dec 17 13:30 tree.html
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37
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super(...param..);
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}
}
Student (String u, int i)
{ navn = u + i; antall++;}
Student (int i)
{ navn="in105-student:”+i;antall++;}
class Student {
static int antall = 0;
String navn;
void lagkurs(String s)
{
for(int i = 0 ; Student.antall < 749 ; i = i +2)
{
in105[i] = new Student (i);
in105[i+1] = new Student (s,i+1);
}
System.out.println("Student nr 99:" + in105[99].navn);
System.out.println("Student nr 100:" + in105[100].navn);
}
class StudentGenerator {
Student [ ] in105 = new Student [750];
}
public static void main ( String[] args)
{ new StudentGenerator().lagkurs(args[0]); }
public class A {
// file:A.java
import java.io.*;
E:\in105-Java\PC-Java>java A
java.lang.ArrayIndexOutOfBoundsException: 0
at A.main(A.java:7)
E:\in105-Java\PC-Java>java A Ola
Student nr 99:Ola99
Student nr 100:in105-student:100
E:\in105-Java\PC-Java>javac A.java
Kompilering og kjøring
©Arne Maus, aug. 1999
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class Tell
{ static int tell;
protected void finalize(){tell++;}
int [] A = new int [100];
}
}
Kjøring:
E:\java-unix>java garb
Genererte obj= 0Ant garb:0
Genererte obj= 10Ant garb:0
Genererte obj= 10Ant garb:0
Genererte obj= 110Ant garb:0
Genererte obj= 110Ant garb:0
Genererte obj= 1110Ant garb:0
Genererte obj= 1110Ant garb:0
Genererte obj= 11110Ant garb:10288
Genererte obj= 11110Ant garb:10288
Genererte obj= 111110Ant garb:109988
void objgen (int i)
{ System.out.println("Genererte obj= “+ gen + “Ant garb:” + Tell.tell);
for (int j = i ; j > 0 ; j--) t = new Tell();
gen += i;
System.out.println("Genererte obj= “+ gen + “Ant garb:” + Tell.tell);
}
public static void main (String [] args )
{ garb g = new garb();
g.objgen(10);
g.objgen(100);
g.objgen(1000);
g.objgen(10000);
g.objgen(100000);
}
public class garb
{ Tell t ;
int gen = 0;
//Fil: garb.java
import java.io.*;
©Arne Maus, aug. 1999
45
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class T2 extends T {
T2 ( )
{ super( );}
T2 (int j) { super(j);}
}
}
T()
{ i = 17;}
T (int j) { i = j;}
public class T {
int i ;
public static void main ( String[] args)
{ T2 t =new T2( ), tt = new T2(5); }
// file:T.java
import java.io.*;
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System.out.println(”her er xx:” + xx.toString( ))
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57
To retrieve a number, use the following code:
Integer n = (Integer)numbers.get("two");
if (n != null) {
System.out.println("two = " + n);
}
This example creates a hashtable of numbers. It uses the names of
the numbers as keys:
Hashtable numbers = new Hashtable();
numbers.put("one", new Integer(1));
numbers.put("two", new Integer(2));
numbers.put("three", new Integer(3));
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©Arne Maus, aug. 1999
59
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©Arne Maus, aug. 1999
// kode som kan gi feil
// f.eks kalles en metode som sier at
// den kaster visse feilmeldinger
}
catch (Exception e){
// kode som behandler feilsituasjonen, f.eks:
e.printStackTrace( );
}
try {
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60
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©Arne Maus, aug. 1999
System.out.println(s+”, tolket som tall” + i);
System.out.print(”Skriv et tall:”)
s = stdin.readLine();
i = Integer.parseInt(s);
int i;
String s = new String();
62
BufferedReader stdin =
new BufferedReader(new FileReader(System.in));
VWDQGDUGLQSXW·YDQVNHOLJ·
©Arne Maus, aug. 1999
63
while ((s = in.readLine()) != null)
s2 += s + ”\n”;
in.close();
} catch (FileNotFoundException e) {
System.out.println(”File not found: ” + args[0])
} catch(IOException e) {
System.out.println(”IO Exception”);
}}
try{
BufferedReader in = new BufferedReader(
new FileReader(args[0]));
String s, s2 = new String();
..public static void main(String[] args) {
import java.io.*;
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©Arne Maus, aug. 1999
}
64
/*public static void prompt (String s)
* public static int
readInt (BufferedReader in)
* public static double readDouble (BufferedReader in)
* public static String readString (BufferedReader in)
* public static char readChar (BufferedReader in)
* public static String writeInt (int number, int align)
* public static String writeDouble (double number, int align, int frac)
* public static BufferedReader open (InputStream in)
* public static BufferedReader open (String filename)
* public static PrintWriter
create (String filename) */
public class Text {
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Les fra
tastatur:
}
// Read and check the rest of the numbers
int number;
for (int i = 2; i <= n; i++) {
Text.prompt(i+">");
number = Text.readInt(in);
if (number > highest) highest = number;
}
System.out.println("That’s enough, thanks");
System.out.println("The highest number was "+ highest);
}
System.out.println("Type them in");
Text.prompt("1>");
int highest = Text.readInt(in);
Text.prompt("How many numbers (1 or more)?");
int n = Text.readInt(in);
BufferedReader in = Text.open(System.in);
class HighestValue {
public static void main(String[] args) throws IOException {
import java.io.*;
import javagently.*;
Les fra fil
og tastatur:
}
}
for (int i = 1; i <= count; i++) {
number = Text.readDouble(fin);
total += number;
}
System.out.println("That’s enough, thanks.");
System.out.println("The total is "+total);
Text.prompt ("How many numbers?");
count = Text.readInt(in);
System.out.println("****** Summing numbers from a file ******");
BufferedReader in = Text.open(System.in);
BufferedReader fin = Text.open("numbers.dat");
int count;
double total = 0;
double number;
public static void main (String [] args) throws IOException {
class Summation2 {
/* Reads in numbers from a file and display their sum.
* Illustrates the declaration of input from both
* the keyboard and a file.
*/
import java.io.*;
import javagently.*;
©Arne Maus, aug. 1999
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©Arne Maus,
aug.september
1999
68
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69
❘ HNVimplements ActionListenerRJHQDYPHWRGHQHNODVVHQGD
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actionPerformed(ActionEvent e) {..’her behandles en
slik hendelse e.}
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public void init() {
b1.addActionListener(new B1());
b2.addActionListener(new B2());
add(b1);
add(b2);
add(t);
}
class B1 implements ActionListener {
public void actionPerformed(ActionEvent e) {
t.setText("Button 1");
}
}
public class Button2NewB extends Applet {
Button
b1 = new Button("Button 1"),
b2 = new Button("Button 2");
TextField t = new TextField(20);
//: Button2NewB.java – s.516 Bruce Eckel
// An application and an applet
import java.awt.*;
import java.awt.event.*; // Must add this
import java.applet.*;
class B2 implements ActionListener {
public void actionPerformed(ActionEvent e) {
t.setText("Button 2");
}
}
// To close the application:
static class WL extends WindowAdapter {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
}
// A main() for the application:
public static void main(String[] args) {
Button2NewB applet = new Button2NewB();
Frame aFrame = new Frame("Button2NewB");
aFrame.addWindowListener(new WL());
aFrame.add(applet, BorderLayout.CENTER);
aFrame.setSize(300,200);
applet.init();
applet.start();
aFrame.setVisible(true);
}
///:~
©Arne Maus, aug. 1999
72
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public class SimpleThread extends Thread{
private int countDown = 5;
private int threadNumber;
private static int threadCount = 0;
public SimpleThread() {
threadNumber = ++threadCount;
System.out.println("Making " + threadNumber);
}
public void run() {
while(true) {
try {System.out.println("Thread " +
threadNumber + "(" + countDown + ")");
sleep(50); // sov 50 millisek.
if(--countDown == 0) return;
} catch (InterruptedException e){
System.out.println(“Exception” + e);
}
}
}
public static void main(String[] args) {
for(int i = 0; i < 5; i++)
new SimpleThread().start();
System.out.println("All Threads Started");
}
} ///:~
//: SimpleThread.java. litt endret Bruce Eckel, 1998
Kjøring:
Making 1
Making 2
Making 3
Making 4
Making 5
All Threads Started
Thread 1(5)
Thread 2(5)
Thread 3(5)
Thread 4(5)
Thread 5(5)
Thread 1(4)
Thread 2(4)
Thread 3(4)
Thread 4(4)
Thread 5(4)
Thread 1(3)
Thread 2(3)
Thread 3(3)
Thread 5(3)
Thread 4(3)
Thread 2(2)
Thread 1(2)
Thread 3(2)
Thread 5(2)
Thread 4(2)
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