Sorry esta es una parte del codigo y la excepcion
metodo que me abre el archivo
public static BufferedReader abrir(){
File f=new File("cuentas2.txt");
BufferedReader br=null;
try{
br=new BufferedReader(new FileReader(f));
}catch(IOException e){
}
return br;
}
metodo que lo usa(t1 y t2 son JTextField y ar2 es un arraylist)
private void debe(ActionEvent e){
BufferedReader br=abrir();
try{
String c=t1.getText();
String c1=t2.getText();
ar2.add(c);
//tamaño del texto que ingreso por t1
int x=c.length();
while(br.readLine()!=null){
String in=br.readLine();
String r=in.substring(0,x);
if(r.equals(c)){
String r1=in.substring(x,in.length());
ar.add(r1+" "+c1);
break;
}
}
br.close();
t1.setText("");
t2.setText("");
}catch(IOException e1){
}
}
este metodo muestra lo q guarde en el ArrayList y lo muestra en JTextArea claro habia otro ArrayList que es ar1 y ar
private void registrar(ActionEvent e){
String t=javax.swing.JOptionPane.showInputDialog("ingrese el codigo:");
cont++;
a.append("..................."+cont+".............."+"\n");
int i=ar.size();
for(int j=0;j<i;j++){
a.append((String)ar2.get(j)+" ");
a.append((String)ar.get(j)+"\n");
}
int i1=ar2.size();
for(int j=i;j<i1;j++){
a.append((String)ar2.get(j)+" ");
a.append((String)ar1.get(j-1)+"\n");
}
a.append(t+"\n");
ar.clear();
ar1.clear();
ar2.clear();
t1.setText("");
t2.setText("");
}
la primera vez que hago click me salle lo que quiero osea esto
...................1..............
10 caja y banco 2514
40 tributos por pagar 654
por la compra de mercaderia
pero cuando quiero volver hacer click en el boton me sale esta excepcion
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at contabilidad.Transaccion.debe(Transaccion.java:178)
at contabilidad.Transaccion.access$2(Transaccion.java:169)
at contabilidad.Transaccion$3.actionPerformed(Transaccion.java:155)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)