BigInteger

[Guest]

Wie kann ich ein BigInteger Objekt in einen String casten?

MFG

 

[SlaterB]

gar nicht

 

[Guest]

Und wenn ich einen BigInteger in ein JLabel schreiben will?

 

[SlaterB]

dann schreibst du dessen Inhalt/ eine dessen Stringrepräsentationen/ eine formatierte Darstellung,
aber castest ihn nicht,

zum Beispiel
String st = bigInt.toString();

 

[Guest]

hmm...

Also hier mal Teilcode

static BigInteger factorial( int n ) 
	  { 
	    BigInteger result = BigInteger.ONE; 
	 
	    if ( n == 0 || n == 1 ) 
	      return result; 
	 
	    if ( n > 1 ) 
	      for ( int i = 1; i <= n; i++ ) 
	        result = result.multiply( BigInteger.valueOf(i) ); 
	 
	    return result; 
	  }

final JLabel bl18= new JLabel ("Fakultät:");//Fakultät
		bl18.setSize(100,20);
		bl18.setLocation(360,170);
		f.add(bl18);
		bl18.setVisible(false);
		
		final JTextField bt18 = new JTextField ();
		bt18.setSize(120,20);
		bt18.setLocation(360,190);
		f.add(bt18);
		bt18.setVisible(false);

		final JLabel bl38 = new JLabel ("=");
		bl38.setSize(10,20);
		bl38.setLocation(495,190);
		f.add(bl38);
		bl38.setVisible(false);
		
		final JLabel bl58 = new JLabel ("");
		bl58.setSize(120,20);
		bl58.setLocation(510,190);
		f.add(bl58);
		bl58.setVisible(false);
		
		final JButton bb18 = new JButton ("Fakultät");
		bb18.setSize(120,20);
		bb18.setLocation(360,215);
		f.add(bb18);
		bb18.setVisible(false);
		
		ActionListener fakultaet = new ActionListener() { 
			public void actionPerformed( ActionEvent e ) { 
				System.out.println(e);
				bt18.setText(bt18.getText().replace(",","."));
				String str=factorial(Integer.parseInt(bt17.getText())).toString();
				bl58.setText(str);
			} 
		}; 

		bb18.addActionListener(fakultaet);//ende Fakultät

Mit der Fehlermeldung

java.awt.event.ActionEvent[ACTION_PERFORMED,cmd=Fakultät,when=1200488683021,modifiers=Button1] on javax.swing.JButton[,360,215,120x20,alignmentX=0.0,alignmentY=0.5,border=javax.swing.plaf.BorderUIResource$CompoundBorderUIResource@dc8569,flags=296,maximumSize=,minimumSize=,preferredSize=,defaultIcon=,disabledIcon=,disabledSelectedIcon=,margin=javax.swing.plaf.InsetsUIResource[top=2,left=14,bottom=2,right=14],paintBorder=true,paintFocus=true,pressedIcon=,rolloverEnabled=true,rolloverIcon=,rolloverSelectedIcon=,selectedIcon=,text=Fakultät,defaultCapable=true]
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
	at java.lang.Integer.parseInt(Integer.java:468)
	at java.lang.Integer.parseInt(Integer.java:497)
	at mt.Tool$10.actionPerformed(Tool.java:932)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
	at java.awt.Component.processMouseEvent(Component.java:6038)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
	at java.awt.Component.processEvent(Component.java:5803)
	at java.awt.Container.processEvent(Container.java:2058)
	at java.awt.Component.dispatchEventImpl(Component.java:4410)
	at java.awt.Container.dispatchEventImpl(Container.java:2116)
	at java.awt.Component.dispatchEvent(Component.java:4240)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
	at java.awt.Container.dispatchEventImpl(Container.java:2102)
	at java.awt.Window.dispatchEventImpl(Window.java:2429)
	at java.awt.Component.dispatchEvent(Component.java:4240)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

 

[SlaterB]

"" geparst ergibt NumberFormatException, korrekt,
hat das was mit dem bisherigen zu tun?

kannst du dir vorstellen, warum es bei "" im Gegensatz zu "5" eine NumberFormatException gibt?
und zur Lösung: wäre doch einfach abzufragen ober der String "" ist

 

[Guest]

ok danke Problem hat sich geklärt...