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POHow to check and Entry before adding and store it in an Array in Java?
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copied!<p>good day.. i have an Address Book Program... it runs properly but it doesn't check if the user input was already stored in an array.. want i want to do is... after getting the user input compare it to the stored entry in an array and when it was unique... it will allow the user to add a new entry...</p> <p>here's my old code in addEntry():</p> <p>public void addEntry() {</p> <pre><code>entry[counter] = new AddressBookEntry(); entry[counter].setName(JOptionPane.showInputDialog("Enter name: ")); entry[counter].setAdd(JOptionPane.showInputDialog("Enter add: ")); entry[counter].setPhoneNo(JOptionPane.showInputDialog("Enter Phone No.: ")); entry[counter].setEmail(JOptionPane.showInputDialog("Enter E-mail: ")); counter++; </code></pre> <p>}</p> <p>and here's what i am planning to do but it turns out to be an ERROR:</p> <p>public void addEntry() {</p> <pre><code> entry[counter] = new AddressBookEntry(); SName = JOptionPane.showInputDialog("Enter name: ");//<-- asks user for the name if (!entry[counter].getName().equals(SName)) {//<--compare entry[counter].setName(JOptionPane.showInputDialog("Enter name: ")); entry[counter].setAdd(JOptionPane.showInputDialog("Enter add: ")); entry[counter].setPhoneNo(JOptionPane.showInputDialog("Enter Phone No.: ")); entry[counter].setEmail(JOptionPane.showInputDialog("Enter E-mail: ")); counter++; } } </code></pre> <p>This is the error: Exception in thread "main" java.lang.NullPointerException at AddressBook.addEntry(AddressBook.java:57) at AddressBook.main(AddressBook.java:28) Java Result: 1 BUILD SUCCESSFUL (total time: 4 seconds)</p> <p>the output only ask user to input for a name and then exit automatically... this might be a logical error... but i don't know what is the possible solution</p> <p>Need Help please thanks</p> <p>here's my complete code:</p> <pre><code>import javax.swing.JOptionPane; import javax.swing.JTextArea; public class AddressBook { private AddressBookEntry entry[]; private int counter; private String SName; private int notfound = 0; public static void main(String[] args) { AddressBook a = new AddressBook(); a.entry = new AddressBookEntry[100]; int option = 0; try { while (option != 5) { String content = "Choose an Option\n\n" + "[1] Add an Entry\n" + "[2] Delete an Entry\n" + "[3] Update an Entry\n" + "[4] View all Entries\n" + "[5] View Specific Entry\n" + "[6] Exit"; option = Integer.parseInt(JOptionPane.showInputDialog(content)); switch (option) { case 1: a.addEntry(); break; case 2: a.deleteEntry(); break; case 3: a.editEntry(); break; case 4: a.viewAll(); break; case 5: a.searchEntry(); break; case 6: System.exit(1); break; default: JOptionPane.showMessageDialog(null, "Invalid Choice!"); } } } catch (NumberFormatException e) { JOptionPane.showMessageDialog(null, "Please Choose a Number in the displayed Menu"); } } public void addEntry() { entry[counter] = new AddressBookEntry(); SName = JOptionPane.showInputDialog("Enter name: "); if (entry[counter] == null && entry[counter].getName() == null && !entry[counter].getName().equals(SName)) { entry[counter].setName(JOptionPane.showInputDialog("Enter name: ")); entry[counter].setAdd(JOptionPane.showInputDialog("Enter add: ")); entry[counter].setPhoneNo(JOptionPane.showInputDialog("Enter Phone No.: ")); entry[counter].setEmail(JOptionPane.showInputDialog("Enter E-mail: ")); counter++; } } /*public void addEntry() { entry[counter] = new AddressBookEntry(); entry[counter].setName(JOptionPane.showInputDialog("Enter name: ")); entry[counter].setAdd(JOptionPane.showInputDialog("Enter add: ")); entry[counter].setPhoneNo(JOptionPane.showInputDialog("Enter Phone No.: ")); entry[counter].setEmail(JOptionPane.showInputDialog("Enter E-mail: ")); counter++; }*/ public void viewAll() { String addText = " NAME\tADDRESS\tPHONE NO.\tE-MAIL ADD\n\n"; int nonNull = 0; for (int i = 0; i < entry.length; i++) { if (entry[i] != null) { addText = addText + entry[i].getInfo() + "\n"; nonNull++; } if (nonNull == counter) { break; } } JOptionPane.showMessageDialog(null, new JTextArea(addText)); } public void searchEntry() { SName = JOptionPane.showInputDialog("Enter Name to find: "); searchMethod(); } public void searchMethod() { for (int i = 0; i < counter; i++) { if (entry[i].getName().equals(SName)) { JOptionPane.showMessageDialog(null, entry[i].getInfo2()); notfound = 0; break; } else { notfound++; } } if (notfound != 0) { JOptionPane.showMessageDialog(null, "Name Not Found!"); } } public void editEntry() { SName = JOptionPane.showInputDialog("Enter Name to edit: "); for (int i = 0; i < counter; i++) { if (entry[i].getName().equals(SName)) { entry[i] = new AddressBookEntry(); entry[i].setName(JOptionPane.showInputDialog("Enter new name: ")); entry[i].setAdd(JOptionPane.showInputDialog("Enter new add: ")); entry[i].setPhoneNo(JOptionPane.showInputDialog("Enter new Phone No.: ")); entry[i].setEmail(JOptionPane.showInputDialog("Enter new E-mail: ")); notfound = 0; break; } else { notfound++; } } if (notfound != 0) { JOptionPane.showMessageDialog(null, "Name Not Found!"); } } public void deleteEntry() { SName = JOptionPane.showInputDialog("Enter Name to delete: "); if (SName == null) { return; } for (int i = 0; i < counter; i++) { if (entry[i] != null && SName.equals(entry[i].getName())) { entry[i] = null; JOptionPane.showMessageDialog(null, "Found!"); break; } } } } </code></pre> <p>hope you can help me... because i still dont understand what to do. So i just show my complete code... thanks for your patience guys...</p>

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