Forum » Programiranje » [java]problem z Throws
[java]problem z Throws
killa bee ::
public class Washer { Laundry laundry = new Laundry(); public void foo() throws ClothingException { laundry.doLaundry(); } public static void main (String[] args) throws ClothingException { Washer a = new Washer(); a.foo(); } }
Kaj bi se zgodilo v primeru da doLaundry() throws ClothingException ?
roko granata ::
V knjigi iz katere je vzet primer (celo na isti starni), ti pod četrto točko piše: "The JVM shuts down".
Če ne verjameš, lahko in je tudi zaželjeno, sprobaš :)
Če ne verjameš, lahko in je tudi zaželjeno, sprobaš :)
roko granata ::
A bereš od konca proti začetku? :)
JVM - Java Virtual Machine; okolje v katerem se izvajajo Java procesi.
Za bolj specifičen opis pogooglaj JVM ali pa preberi prvo/drugo poglavje.
Na kratko - program se ti sesuje.
JVM - Java Virtual Machine; okolje v katerem se izvajajo Java procesi.
Za bolj specifičen opis pogooglaj JVM ali pa preberi prvo/drugo poglavje.
Na kratko - program se ti sesuje.
killa bee ::
jst vem kaj pomeni JVM ampak ne vem kaj pomeni "The JVM shuts down".
sm naredil programček in mi napiše:
a to se torej zgodi?
sm naredil programček in mi napiše:
Exception in thread "main" ClothingException at Washer.foo(Washer.java:15) at Washer.main(Washer.java:20)
a to se torej zgodi?
Zgodovina sprememb…
- spremenilo: killa bee ()
Wrop ::
Če nikjer v programu ne zajemaš izjem, potem zate to naredi JVM.
Lahko si zamišliš tako, da JVM pokliče tvojo main metodo v try catch stavku.
Lahko si zamišliš tako, da JVM pokliče tvojo main metodo v try catch stavku.
killa bee ::
Men to napiše, a to pomen da se je JVM ugasnil?
Exception in thread "main" ClothingException at Washer.foo(Washer.java:15) at Washer.main(Washer.java:20)
kunigunda ::
kaj pa v Linuxu
ps -ef|grep java
Ce mas pa pot nastimano do jave, pa lohk tud
jps
Zgodovina sprememb…
- spremenilo: kunigunda ()
kunigunda ::
Mogoce je pa bolje za zacetek, da se vprasas ali imas pot nastimano ali ne, in kako to preveriti, predno se lotis programiranja :)
Google is your friend.
Google is your friend.
killa bee ::
jst mislilm da imam pot naštimano ker se postavim v datoteko kjer se xyz.java file nahaja ter ga kompajlam z ukazom javac xyz.java. Nisem posebno nastavljal poti.
Zgodovina sprememb…
- spremenilo: killa bee ()
kunigunda ::
Pol pa enostavno pozeni ukaz 'jps' pa bos videl ce ti jav error al ti pa izpise jvm procese
killa bee ::
Zaženem svoj testni program in mi najrej izpiše
po tem upišem
pa mi izpiše
A to pomeni da se je JVM ugasnil?
Exception in thread "main" ClothingException at Washer.foo(Washer.java:15) at Washer.main(Washer.java:20)
po tem upišem
jps
pa mi izpiše
6398 Jps
A to pomeni da se je JVM ugasnil?
Zgodovina sprememb…
- spremenilo: killa bee ()
kunigunda ::
Ja, samo "samega sebe" je nasel :)
Sicer pa ponavadi main metodo ne throw-as.
public static void main (String[] args) {
Washer a = new Washer();
try {
a.foo();
} catch (Exception e) {
System.err.println("Crknu zaradi " + e.getMessage());
}
}
Sicer pa ponavadi main metodo ne throw-as.
public static void main (String[] args) {
Washer a = new Washer();
try {
a.foo();
} catch (Exception e) {
System.err.println("Crknu zaradi " + e.getMessage());
}
}
Zgodovina sprememb…
- spremenilo: kunigunda ()
kr?en ::
http://docs.oracle.com/javase/tutorial/...
Pa si malo preberi, da ne bos spraseval bedarij.
Pa ce bi znal uporabljat google/stackoverflow, bi bilo tudi zelo super.
Pa si malo preberi, da ne bos spraseval bedarij.
Pa ce bi znal uporabljat google/stackoverflow, bi bilo tudi zelo super.
killa bee ::
a mogoče kdo ve zakaj je spodnjih 5,6,7... zvokov popolnoma enakih?
import java.awt.*; import javax.swing.*; import javax.sound.midi.*; import java.util.*; import java.awt.event.*; public class BeatBox { JPanel mainPanel; ArrayList<JCheckBox> checkboxList; Sequencer sequencer; Sequence sequence; Track track; JFrame theFrame; String[] instrumentNames = {"Bass Drum", "Closed Hi-Hat", "Open Hi-Hat","Acoustic Snare", "Crash Cymbal", "Hand Clap", "High Tom", "Hi Bongo", "Maracas", "Whistle", "Low Conga", "Cowbell", "Vibraslap", "Low-mid Tom", "High Agogo", "Open Hi Conga"}; int[] instruments = {35,42,46,38,49,39,50,60,70,72,64,56,58,47,67,63}; public static void main (String[] args) { new BeatBox().buildGUI(); } public void buildGUI() { theFrame = new JFrame("Cyber BeatBox"); theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); BorderLayout layout = new BorderLayout(); JPanel background = new JPanel(layout); background.setBorder(BorderFactory.createEmptyBorder(10,10,10,10)); checkboxList = new ArrayList<JCheckBox>(); Box buttonBox = new Box(BoxLayout.Y_AXIS); JButton start = new JButton("Start"); start.addActionListener(new MyStartListener()); buttonBox.add(start); JButton stop = new JButton("Stop"); stop.addActionListener(new MyStopListener()); buttonBox.add(stop); JButton upTempo = new JButton("Tempo Up"); upTempo.addActionListener(new MyUpTempoListener()); buttonBox.add(upTempo); JButton downTempo = new JButton("Tempo Down"); downTempo.addActionListener(new MyDownTempoListener()); buttonBox.add(downTempo); Box nameBox = new Box(BoxLayout.Y_AXIS); for (int i = 0; i < 16; i++) { nameBox.add(new Label(instrumentNames[i])); } background.add(BorderLayout.EAST, buttonBox); background.add(BorderLayout.WEST, nameBox); theFrame.getContentPane().add(background); GridLayout grid = new GridLayout(16,16); grid.setVgap(1); grid.setHgap(2); mainPanel = new JPanel(grid); background.add(BorderLayout.CENTER, mainPanel); for (int i = 0; i < 256; i++) { JCheckBox c = new JCheckBox(); c.setSelected(false); checkboxList.add(c); mainPanel.add(c); } // end loop setUpMidi(); theFrame.setBounds(50,50,300,300); theFrame.pack(); theFrame.setVisible(true); } // close method public void setUpMidi() { try { sequencer = MidiSystem.getSequencer(); sequencer.open(); sequence = new Sequence(Sequence.PPQ,4); track = sequence.createTrack(); sequencer.setTempoInBPM(120); } catch(Exception e) {e.printStackTrace();} } // close method public void buildTrackAndStart() { int[] trackList = null; sequence.deleteTrack(track); track = sequence.createTrack(); for (int i = 0; i < 16; i++) { trackList = new int[16]; int key = instruments[i]; for (int j = 0; j < 16; j++ ) { JCheckBox jc = (JCheckBox) checkboxList.get(j + (16*i)); if ( jc.isSelected()) { trackList[j] = key; } else { trackList[j] = 0; } } // close inner loop makeTracks(trackList); track.add(makeEvent(176,1,127,0,16)); } // close outer track.add(makeEvent(192,9,1,0,15)); try { sequencer.setSequence(sequence); sequencer.setLoopCount(sequencer.LOOP_CONTINUOUSLY); sequencer.start(); sequencer.setTempoInBPM(120); } catch(Exception e) {e.printStackTrace();} } // close buildTrackAndStart method public class MyStartListener implements ActionListener { public void actionPerformed(ActionEvent a) { buildTrackAndStart(); } } // close inner class public class MyStopListener implements ActionListener { public void actionPerformed(ActionEvent a) { sequencer.stop(); } } // close inner class public class MyUpTempoListener implements ActionListener { public void actionPerformed(ActionEvent a) { float tempoFactor = sequencer.getTempoFactor(); sequencer.setTempoFactor((float)(tempoFactor * 1.03)); } } // close inner class public class MyDownTempoListener implements ActionListener { public void actionPerformed(ActionEvent a) { float tempoFactor = sequencer.getTempoFactor(); sequencer.setTempoFactor((float)(tempoFactor * .97)); } } // close inner class public void makeTracks(int[] list) { for (int i = 0; i < 16; i++) { int key = list[i]; if (key != 0) { track.add(makeEvent(144,9,key, 100, i)); track.add(makeEvent(128,9,key, 100, i+1)); } } } public MidiEvent makeEvent(int comd, int chan, int one, int two, int tick) { MidiEvent event = null; try { ShortMessage a = new ShortMessage(); a.setMessage(comd, chan, one, two); event = new MidiEvent(a, tick); } catch(Exception e) {e.printStackTrace(); } return event; } } // close class
Zgodovina sprememb…
- spremenilo: killa bee ()
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