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Java II - 1
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Java II - 3
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//-Fil:Sortera.java--------------------------------------class Sortera
{
public static void bubbel(Sorteringsbar[] element)
{
boolean klart = false; //Sant när allt är sorterat
Java II - 4
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public final class Test
{
public static void main(String[] argument)
{
Arbetare[] anställd = new Arbetare[5];
while (!klart)
{
klart = true;
anställd[0]
anställd[1]
anställd[2]
anställd[3]
anställd[4]
for (int i=0; i<element.length - 1; i++)
{
Sorteringsbar temp = element[i];
=
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=
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new
new
new
new
new
Arbetare("Gustaf", 203000);
Arbetare("Kajsa", 197000);
Arbetare("Lotta", 356000);
Arbetare("Fredrik", 245000);
Arbetare("Lars", 321000);
Sortera.bubbel(anställd);
for (int i=0; i<anställd.length; i++)
anställd[i].print();
if (temp.mindre(element[i+1]))
{
element[i] = element[i+1];
element[i+1] = temp;
klart = false;
}
Student[] elev = new Student[4];
elev[0]
elev[1]
elev[2]
elev[3]
}
}
}
}
//--------------------------------------------------------
=
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new
new
new
new
Student("Erik", "spelar jazz.");
Student("Karl", ӌker skidor.");
Student("Stina", "läser böcker.");
Student("Karin", "reser mycket.");
Sortera.bubbel(elev);
for (int i=0; i<elev.length; i++)
elev[i].print();
}
}
2
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Java II - 5
Java II - 6
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//-Fil:Person.java---------------------------------------public class Person
{
protected String name;
//-Fil:Arbetare.java-------------------------------------public class Arbetare extends Person
implements Sorteringsbar
{
private int inkomst;
Person(String namn)
{
name = namn;
}
public void print()
{
System.out.println("Person: " + name);
}
}
//--------------------------------------------------------
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Arbetare(String namn, int inkomst)
{
super(namn); //M†ste skrivas p† f”rsta raden!
this.inkomst = inkomst;
}
public void print()
{
super.print();
System.out.println("Inkomst: " + inkomst + " kr\n");
}
public boolean mindre(Sorteringsbar element)
{
Arbetare jobbare = (Arbetare)element;
return inkomst < jobbare.inkomst;
//-Fil: Sorteringsbar.java--------------------------------
interface Sorteringsbar
{
public boolean mindre(Sorteringsbar element);
}
}
}
//--------------------------------------------------------
//--------------------------------------------------------
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Java II - 7
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//-Fil:Student.java--------------------------------------public class Student extends Person
implements Sorteringsbar
{
private String hobby;
Student(String namn, String hobby)
{
super(namn);
this.hobby = hobby;
}
public void print()
{
super.print();
System.out.println("Hobby: " + hobby + "\n");
}
public boolean mindre(Sorteringsbar element)
{
Student elev = (Student)element;
if (name.compareTo(elev.name) < 0)
return true;
else
return false;
}
}
//--------------------------------------------------------
Java II - 8
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Utskrift
Person: Lotta
Inkomst: 356000 kr
Person: Lars
Inkomst: 321000 kr
Person: Fredrik
Inkomst: 245000 kr
Person: Gustaf
Inkomst: 203000 kr
Person: Kajsa
Inkomst: 197000 kr
Person: Stina
Hobby: läser böcker
Person: Karl
Hobby: åker skidor
Person: Karin
Hobby: reser mycket
Person: Erik
Hobby: spelar jazz
4
Java II - 9
Java II - 10
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java.text.*;
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import java.text.*;
NumberFormat r = NumberFormat.getInstance();
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r.format(x);
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class Tid
{
private int timmar = 3;
private int minuter = 24;
private int sekunder = 7;
public String toString()
{
NumberFormat nf =
NumberFormat.getInstance();
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r.setMaximumFractionDigits(n); //högst n decimaler
r.setMaximumIntegerDigits(n); //högst n heltalssiffror
r.setMinimumFractionDigits(n); //minst n decimaler
r.setMinimumIntegerDigits(n); //minst n heltalssiffror
r.setGroupingUsed(true);
//siffrorna ska grupperas
r.setGroupingUsed(true); //siffrorna ska inte grupperas
nf.setMinimumIntegerDigits(2);
String tid = nf.format(timmar) + ”:”
+ nf.format(minuter) + ”:”
+ nf.format(sekunder);
return tid;
}
}
Ger följande sträng
03:24:07
5
Java II - 11
Java II - 12
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System.out
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println(Object), println(String),
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println(int), println(long),
println(float), println(double),
println(bolean)
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System.out.print(”Vad heter du: ”);
System.out.flush();
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Java II - 14
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Java II - 13
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import java.io.*;
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java.io
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public class Rad
{
public static void main(String[] argument)
throws IOException
{
BufferedReader MinaInData = new
BufferedReader(new
InputStreamReader(System.in));
String namnet;
System.out.print("Vad heter du: ");
System.out.flush();
BufferedReader MinaInData =
new BufferedReader(
new InputStreamReader(System.in));
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namnet = MinaInData.readLine();
System.out.println("Hej, " + namnet + "!");
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}
readLine
}
Exempel på exekvering
==> java Rad
Vad heter du: Hans-Edy Mårtensson
Hej, Hans-Edy Mårtensson!
==>
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Java II - 15
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import java.io.*;
public class Tal
{
public static void main(String[] argument)
throws IOException
{
BufferedReader MinaInData =
new BufferedReader(
new InputStreamReader(System.in));
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System.out.print("Skriv ett heltal: ");
System.out.flush();
String textRad = MinaInData.readLine();
textRad = textRad.trim(); //Rensar bort blanktecken
String textRad = minaInData.readLine();
int mittHeltal = Integer.parseInt(textRad);
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int helTalet = Integer.parseInt(textRad);
System.out.println("Heltalet „r: " + helTalet);
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System.out.print("Skriv ett decimaltal: ");
System.out.flush();
textRad = MinaInData.readLine();
textRad = textRad.trim();
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Java II - 16
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double decimalTalet =
Double.valueOf(textRad).doubleValue();
String textRad = minaInData.readLine();
int mittDecimaltal =
Double.valueOf(textRad).doubleValue();
System.out.println("Decimaltalet „r: " +
decimalTalet);
}
}
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Java II - 17
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FileOutputStream
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FilterOutputStream
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BufferedInputStream
ByteArrayOutputStream
DataOutputStream
PrintStream
BufferedOutputStream
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Reader
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PipedReader
InputStreamReader
OutputStreamWriter
BufferedWriter
CharArrayReader
FileReader
BufferedReader
Java II - 20
FileWriter
FilterReader
PipedWriter
StringReader
LineNumberReader
PushbackReader
FilterWriter
CharArrayWriter
PrintWriter
StringWriter
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Java II - 21
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import java.io.*;
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public class Kopiera
{
public static void main(String[] argument)
throws IOException, FileNotFoundException
{
//Vi skapar en indataström från tangentbordet
BufferedReader inStrom =
new BufferedReader(
new InputStreamReader(System.in));
//Vi skapar en teckenström från den fil som ska
//kopieras
System.out.print("Infilens namn? : ");
System.out.flush();
String filNamnet = inStrom.readLine();
BufferedReader inFil =
new BufferedReader(new FileReader(filNamnet));
//Vi skapar en teckenström till den nya kopian
System.out.print("Utfilens namn? : ");
System.out.flush();
filNamnet = inStrom.readLine();
PrintWriter utFil =
new PrintWriter(
new BufferedWriter(new FileWriter(filNamnet)));
//Programmet forsätter på nästa sida
1
(WWH[HPSHOSnDFFHVVJava II - 23
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//Och nu kopierar vi den ena filen till den andra
int n = 0;
while (true)
{
String rad = inFil.readLine();
if (rad == null) break;
utFil.println(rad);
n++;
}
utFil.close();
inFil.close();
System.out.println(n + " rader kopierade");
}
}
1