查找和替换链表中的节点

Question

我需要能够在链表中查找和替换用户信息。我已经阅读了一些教程和示例，但似乎不起作用。用于链表的set方法不起作用。所以我想知道我是不是实施错了。任何帮助都会很棒。此外，仅供参考，我的链表是从一个文件加载的，基本上它只是用户信息，每个元素都在不同的行上。

即

        int index = account.indexOf(hobby);
        account.set(index, "New String");

代码：

private void jButtonP1ActionPerformed(java.awt.event.ActionEvent evt) {
    LinkedList<Account> account = new LinkedList<Account>();
    //user information
    String username = jTextFieldP3.getText();
    String password = jPasswordFieldP1.getText();
    String email = jTextFieldP4.getText();
    String name = jTextFieldP1.getText();
    String breed = (String) jComboBoxP4.getSelectedItem();
    String gender = (String) jComboBoxP3.getSelectedItem();
    String age = (String) jComboBoxP1.getSelectedItem();
    String state = (String) jComboBoxP2.getSelectedItem();
    String hobby = jTextFieldP2.getText();
    //combo boxes
    String passchange = (String) jComboBoxP13.getSelectedItem();
    String emailchange = (String) jComboBoxP14.getSelectedItem();
    String namechange = (String) jComboBoxP6.getSelectedItem();
    String breedchange = (String) jComboBoxP7.getSelectedItem();
    String genderchange = (String) jComboBoxP8.getSelectedItem();
    String agechange = (String) jComboBoxP9.getSelectedItem();
    String statechange = (String) jComboBoxP10.getSelectedItem();
    String hobbychange = (String) jComboBoxP11.getSelectedItem();
    String accountcancel = (String) jComboBoxP5.getSelectedItem();
    Account a = new Account(username, password, email, name, breed, gender, age, state, hobby);
    account.add(a);
    if(username.equals("") || password.equals("") || email.equals("")) // If password and username is empty > Do this >>>
    {
        jButtonP1.setEnabled(false);
        jTextFieldP3.setText("");
        jPasswordFieldP1.setText("");
        jTextFieldP4.setText("");
        jButtonP1.setEnabled(true);
        this.setVisible(true);
    }
    else if(a.onList(username) || a.onList(password) || a.onList(email))
    {
        int index = account.indexOf(hobby);
        account.set(index, "New String");
    }
    else
    {
    }
}

Answer 1

int index = account.indexOf(hobby);
account.set(index, "New String");

这里的问题是indexOf（）将返回-1，因为它在具有Account值的列表中搜索String值。

不能按列表中元素的字段进行搜索。您必须手动搜索该帐户，然后设置爱好字段：

for(Account acc : account){
    if(acc.getHobby().equals(hobby)){
        acc.setHobby("New String");
    }
}