[英]Can't populate a JList from a TXT File
Here's my working code that reads a TXT File and shows it in the console: 这是我的工作代码,它读取TXT文件并在控制台中显示:
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import javax.swing.DefaultListModel;
import javax.swing.JList;
public class LeerArchivoDeTexto {
public static void main(String[] args) {
File archivo = new File("Archivo.txt");
BufferedReader lector = null;
DefaultListModel lista = new DefaultListModel();
JList jList1 = new JList();
try {
lector = new BufferedReader(new FileReader(archivo));
String texto = null;
while ((texto = lector.readLine()) != null) {
lista.addElement(texto);
System.out.println(texto);
}
jList1.setModel(lista);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (lector != null) {
lector.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
The thing is that I want to load the data I have in my TXT File to a JList
. 问题是我想将我的TXT文件中的数据加载到
JList
。 The commented lines which envolve the JList
aren't working. 包含
JList
的注释行无效。 Any ideas? 有任何想法吗?
The JList
is not instantiated because you explicitly set it to null: JList
未实例化,因为您明确将其设置为null:
JList JList1 = null; // not initialized
So when trying to set the model to it I assume you get a NullPointerException
on this line: 因此,当尝试将模型设置为它时,我假设您在此行上获得
NullPointerException
:
JList1.setModel(lista); // NPE here
You need to instantiate the JList
and set the model to it like this: 您需要实例化
JList
并将模型设置为它,如下所示:
JList jList1 = new JList();
jList1.setModel(lista);
If you constract the JList correctly via 如果你通过正确构造JList
JList JList1 = new JList();
you can uncomment all your lines and it will work fine. 你可以取消注释所有的行,它会正常工作。 Of course you then have to add this list to a swing container.
当然,您必须将此列表添加到swing容器中。
You never create a new instance of a JList
that is asigned to JList1
, yet you are trying to call a method on that variable and most likely get a NullPointerException
. 您永远不会创建一个与
JList1
的JList
的新实例,但是您尝试在该变量上调用方法,并且很可能会获得NullPointerException
。
Instead of assigning null to JList1
, assign a new instance. 而不是为
JList1
分配null, JList1
分配一个新实例。
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