Erro NullPointerException

vagner.analista · Junho 16, 2010, 8:55pm

Pessoal alguém pode me ajudar??? ta dando um erro de null point exception e não consigo enxergar na onde ta esse erro. Vejam minhas classes abaixo:

[code]package br.iterator.semPadrao;

/**
*

@author Vagner Duarte
*/
public class Aluno {
String nome;
String sobrenome;
String tel;
String cpf;

public Aluno(String nome, String sobrenome, String tel, String cpf) {
this.nome = nome;
this.sobrenome = sobrenome;
this.tel = tel;
this.cpf = cpf;
}

public String getCpf() {
return cpf;
}

public void setCpf(String cpf) {
this.cpf = cpf;
}

public String getNome() {
return nome;
}

public void setNome(String nome) {
this.nome = nome;
}

public String getSobrenome() {
return sobrenome;
}

public void setSobrenome(String sobrenome) {
this.sobrenome = sobrenome;
}

public String getTel() {
return tel;
}

public void setTel(String tel) {
this.tel = tel;
}

}[/code]

[code]package br.iterator.semPadrao;

import javax.swing.JOptionPane;

/**
*

@author Vagner Duarte
*/
public class IteratorGui extends javax.swing.JFrame {

/** Creates new form IteratorGui */
public IteratorGui() {
initComponents();
}

/** This method is called from within the constructor to
- initialize the form.
- WARNING: Do NOT modify this code. The content of this method is
- always regenerated by the Form Editor.
  */
  @SuppressWarnings(“unchecked”)
  //
  private void initComponents() {
  
  jLabel1 = new javax.swing.JLabel();
  jLabel2 = new javax.swing.JLabel();
  jLabel3 = new javax.swing.JLabel();
  jLabel4 = new javax.swing.JLabel();
  jLabel5 = new javax.swing.JLabel();
  jt_nome = new javax.swing.JTextField();
  jt_sobrenome = new javax.swing.JTextField();
  jt_tel = new javax.swing.JTextField();
  jt_cpf = new javax.swing.JTextField();
  bt_gravar = new javax.swing.JButton();
  bt_cancelar = new javax.swing.JButton();
  bt_cadastro = new javax.swing.JButton();
  
  setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
  setTitle(“Cadastro de Alunos.:”);
  setResizable(false);
  
  jLabel1.setFont(new java.awt.Font(“Tahoma”, 1, 14)); // NOI18N
  jLabel1.setForeground(java.awt.Color.blue);
  jLabel1.setText(“Cadastro de Alunos Utilizando Lista:”);
  
  jLabel2.setText(“Nome:”);
  
  jLabel3.setText(“Sobrenome:”);
  
  jLabel4.setText(“Telefone:”);
  
  jLabel5.setText(“Cpf:”);
  
  jt_nome.addActionListener(new java.awt.event.ActionListener() {
  public void actionPerformed(java.awt.event.ActionEvent evt) {
  jt_nomeActionPerformed(evt);
  }
  });
  
  jt_sobrenome.addActionListener(new java.awt.event.ActionListener() {
  public void actionPerformed(java.awt.event.ActionEvent evt) {
  jt_sobrenomeActionPerformed(evt);
  }
  });
  
  try{
  javax.swing.text.MaskFormatter tel = new javax.swing.text.MaskFormatter("(##)####-####");
  jt_tel = new javax.swing.JFormattedTextField(tel);
  }
  catch (Exception e){
  }
  jt_tel.addActionListener(new java.awt.event.ActionListener() {
  public void actionPerformed(java.awt.event.ActionEvent evt) {
  jt_telActionPerformed(evt);
  }
  });
  
  try{
  javax.swing.text.MaskFormatter cpf = new javax.swing.text.MaskFormatter("###.###.###-##");
  jt_cpf = new javax.swing.JFormattedTextField(cpf);
  }
  catch (Exception e){
  }
  jt_cpf.addActionListener(new java.awt.event.ActionListener() {
  public void actionPerformed(java.awt.event.ActionEvent evt) {
  jt_cpfActionPerformed(evt);
  }
  });
  
  bt_gravar.setText(“Gravar”);
  bt_gravar.addActionListener(new java.awt.event.ActionListener() {
  public void actionPerformed(java.awt.event.ActionEvent evt) {
  bt_gravarActionPerformed(evt);
  }
  });
  
  bt_cancelar.setText(“Cancelar”);
  
  bt_cadastro.setText(“Mostrar Cadastro”);
  bt_cadastro.addActionListener(new java.awt.event.ActionListener() {
  public void actionPerformed(java.awt.event.ActionEvent evt) {
  bt_cadastroActionPerformed(evt);
  }
  });
  
  javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
  getContentPane().setLayout(layout);
  layout.setHorizontalGroup(
  layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
  .addGroup(layout.createSequentialGroup()
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
  .addGroup(layout.createSequentialGroup()
  .addContainerGap()
  .addComponent(bt_gravar)
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addComponent(bt_cancelar)
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addComponent(bt_cadastro))
  .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
  .addGap(68, 68, 68)
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
  .addGroup(layout.createSequentialGroup()
  .addComponent(jLabel3)
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addComponent(jt_sobrenome, javax.swing.GroupLayout.DEFAULT_SIZE, 212, Short.MAX_VALUE))
  .addGroup(layout.createSequentialGroup()
  .addComponent(jLabel2)
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addComponent(jt_nome, javax.swing.GroupLayout.DEFAULT_SIZE, 239, Short.MAX_VALUE))
  .addComponent(jLabel1)
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
  .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
  .addComponent(jLabel5)
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addComponent(jt_cpf))
  .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
  .addComponent(jLabel4)
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addComponent(jt_tel, javax.swing.GroupLayout.PREFERRED_SIZE, 117, javax.swing.GroupLayout.PREFERRED_SIZE))))))
  .addContainerGap(58, Short.MAX_VALUE))
  );
  layout.setVerticalGroup(
  layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
  .addGroup(layout.createSequentialGroup()
  .addGap(47, 47, 47)
  .addComponent(jLabel1)
  .addGap(48, 48, 48)
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
  .addComponent(jLabel2)
  .addComponent(jt_nome, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
  .addComponent(jLabel3)
  .addComponent(jt_sobrenome, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
  .addComponent(jLabel4)
  .addComponent(jt_tel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
  .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
  .addComponent(jLabel5)
  .addComponent(jt_cpf, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
  .addGap(18, 18, 18)
  .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
  .addComponent(bt_gravar)
  .addComponent(bt_cancelar)
  .addComponent(bt_cadastro))
  .addContainerGap(44, Short.MAX_VALUE))
  );
  
  java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
  setBounds((screenSize.width-408)/2, (screenSize.height-334)/2, 408, 334);
  }//
private void jt_nomeActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}

private void jt_sobrenomeActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}

private void jt_telActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}

private void jt_cpfActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}

private void limpacampos(){
jt_cpf.setText("");
jt_nome.setText("");
jt_sobrenome.setText("");
jt_tel.setText("");

}
private void bt_gravarActionPerformed(java.awt.event.ActionEvent evt) {
String nome = jt_nome.getText();
String sobrenome = jt_sobrenome.getText();
String cel = jt_tel.getText();
String cpf = jt_cpf.getText();
CadastroAluno cadastro = new CadastroAluno();
cadastro.addAluno(nome, sobrenome, cel, cpf);
limpacampos();
JOptionPane.showMessageDialog(null, “Cadastro Efetuado com sucesso!!”);
jt_nome.requestFocus();
}

private void bt_cadastroActionPerformed(java.awt.event.ActionEvent evt) {
MostraCadastro mostrar = new MostraCadastro();
mostrar.show();
dispose();
mostrar.arraylistcadastro();
}

// Variables declaration - do not modify
private javax.swing.JButton bt_cadastro;
private javax.swing.JButton bt_cancelar;
private javax.swing.JButton bt_gravar;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JTextField jt_cpf;
private javax.swing.JTextField jt_nome;
private javax.swing.JTextField jt_sobrenome;
private javax.swing.JTextField jt_tel;
// End of variables declaration

}[/code]

[code]package br.iterator.semPadrao;

import java.util.ArrayList;

/**
*

@author Vagner Duarte
*/
public class CadastroAluno {

private ArrayList alunos;

public void addAluno(String nome, String sobrenome, String tel, String cpf){
alunos = new ArrayList();
Aluno aluno = new Aluno(nome, sobrenome,tel,cpf);
alunos.add(aluno);
}
public ArrayList lista_alunos(){
return alunos;
}
}[/code]

[code]package br.iterator.semPadrao;

import java.util.ArrayList;
import javax.swing.JOptionPane;

/**
*

@author Vagner Duarte
*/
public class MostraCadastro extends javax.swing.JFrame {
ArrayList alunos;

public MostraCadastro() {
initComponents();
}

public void arraylistcadastro(){
CadastroAluno cadastro = new CadastroAluno();
alunos = new ArrayList();
alunos = cadastro.lista_alunos();

if(alunos.size() == 0){
JOptionPane.showMessageDialog(null, “A lista esta vazia”);
}

for(int i =0; i <= alunos.size();i++){
Aluno aluno = (Aluno) alunos.get(i);
jta_cadastro.append(aluno.getNome());
jta_cadastro.append(aluno.getSobrenome());
jta_cadastro.append(aluno.getTel());
jta_cadastro.append(aluno.getCpf());
}

}

@SuppressWarnings(“unchecked”)
//
private void initComponents() {

 jLabel1 = new javax.swing.JLabel();
 jScrollPane1 = new javax.swing.JScrollPane();
 jta_cadastro = new javax.swing.JTextArea();

 setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
 setResizable(false);

 jLabel1.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
 jLabel1.setForeground(java.awt.Color.blue);
 jLabel1.setText("Alunos Cadastrados:");

 jta_cadastro.setColumns(20);
 jta_cadastro.setRows(5);
 jScrollPane1.setViewportView(jta_cadastro);

 javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
 getContentPane().setLayout(layout);
 layout.setHorizontalGroup(
     layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
     .addGroup(layout.createSequentialGroup()
         .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
             .addGroup(layout.createSequentialGroup()
                 .addGap(131, 131, 131)
                 .addComponent(jLabel1))
             .addGroup(layout.createSequentialGroup()
                 .addGap(20, 20, 20)
                 .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 346, javax.swing.GroupLayout.PREFERRED_SIZE)))
         .addContainerGap(34, Short.MAX_VALUE))
 );
 layout.setVerticalGroup(
     layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
     .addGroup(layout.createSequentialGroup()
         .addGap(33, 33, 33)
         .addComponent(jLabel1)
         .addGap(18, 18, 18)
         .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 152, javax.swing.GroupLayout.PREFERRED_SIZE)
         .addContainerGap(80, Short.MAX_VALUE))
 );

 java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
 setBounds((screenSize.width-408)/2, (screenSize.height-334)/2, 408, 334);

}//

/**

@param args the command line arguments
*/

// Variables declaration - do not modify
private javax.swing.JLabel jLabel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTextArea jta_cadastro;
// End of variables declaration

}[/code]

Adelar · Junho 16, 2010, 9:30pm

Olá,
posta a exception aqui. Vai ser mais fácil verificar com ela.

Att.

vagner.analista · Junho 16, 2010, 9:34pm

segue o erro:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at br.iterator.semPadrao.MostraCadastro.arraylistcadastro(MostraCadastro.java:33) at br.iterator.semPadrao.IteratorGui.bt_cadastroActionPerformed(IteratorGui.java:225) at br.iterator.semPadrao.IteratorGui.access$500(IteratorGui.java:20) at br.iterator.semPadrao.IteratorGui$6.actionPerformed(IteratorGui.java:113) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995) at javax.swing.AbstractButton$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:6216) at javax.swing.JComponent.processMouseEvent(JComponent.java:3265) at java.awt.Component.processEvent(Component.java:5981) at java.awt.Container.processEvent(Container.java:2041) at java.awt.Component.dispatchEventImpl(Component.java:4583) at java.awt.Container.dispatchEventImpl(Container.java:2099) at java.awt.Component.dispatchEvent(Component.java:4413) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4556) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4220) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4150) at java.awt.Container.dispatchEventImpl(Container.java:2085) at java.awt.Window.dispatchEventImpl(Window.java:2475) at java.awt.Component.dispatchEvent(Component.java:4413) at java.awt.EventQueue.dispatchEvent(EventQueue.java:599) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Adelar · Junho 16, 2010, 9:42pm

Olá,
acho que o erro está na linha 26 do MostraCadastro. Está como:

for(int i =0; i <= alunos.size();i++){

acho que deveria ser:

for(int i =0; i < alunos.size();i++){

Att.

vagner.analista · Junho 16, 2010, 9:53pm

não é esse o erro não…fiz o teste

eu to desconfiado dessa linha aqui ó:

CadastroAluno cadastro = new CadastroAluno();

Será que quando eu instanciou aqui, ele não zera o objeto aluno e ai tento acessar os atributos, ai da o erro??

Adelar · Junho 16, 2010, 10:15pm

Pois é, não tinha notado… são dois problemas…

o problema primeiro esta nas linhas 19 e 20 do MostraCadastro, nas quais você seta a mesma variável duas vezes.

Deve haver um método lista_alunos() na classe CadastroAluno né? O segundo problema é que este método retorna a variável alunos da classe CadastroAluno, que ainda não foi inicializada (está sendo inicializada somente no método addAluno(String nome, String sobrenome, String tel, String cpf)).

Att.

system · Dezembro 29, 2015, 5:56am

Erro NullPointerException

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