Kann NullPointerException mit JTextArea nicht beheben

Question

Ich versuche, ein textbasiertes Abenteuer zu machen, das in einem Jframe läuft, aber wenn ich das Programm starte, bekomme ich einen NullPointer Fehler in Zeile 97 (first time i append console in the game method) und ich habe keine Ahnung, wie ich es beheben kann. Ich bin relativ neu zu java, also ist es wahrscheinlich etwas einfaches, das ich gerade nicht weiß.

mein Code ist hier

package window; 

import java.awt.EventQueue; 

import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.border.EmptyBorder; 
import javax.swing.JButton; 

import java.awt.event.ActionListener; 
import java.awt.event.ActionEvent; 

import javax.swing.JTextArea; 
import javax.swing.JTextField; 

public class Gui extends JFrame { 

public JPanel contentPane; 
public static JTextField input; 
public static JButton send; 
public static JTextArea console; 
public static JTextArea invintory; 
public static JTextArea stats; 
static String i = ""; 

/** 
* Launch the application. 
*/ 



/** 
* Create the frame. 
*/ 
public Gui() { 
    //variables 

    int Gold = 20; 
    int Health = 100; 
    int MaxHealth = 100; 


    //variables end 
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    setBounds(100, 100, 450, 300); 
    contentPane = new JPanel(); 
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); 
    setContentPane(contentPane); 
    contentPane.setLayout(null); 

    JTextArea console = new JTextArea(); 
    console.setBounds(10, 11, 281, 214); 
    contentPane.add(console); 

    input = new JTextField(); 
    input.setBounds(10, 236, 281, 20); 
    contentPane.add(input); 
    input.setColumns(10); 

    JTextArea stats = new JTextArea(); 
    stats.setBounds(301, 11, 123, 53); 
    contentPane.add(stats); 

    JTextArea invintory = new JTextArea(); 
    invintory.setBounds(301, 75, 128, 137); 
    contentPane.add(invintory); 

    JButton send = new JButton("Send"); 
    send.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 
      String i = input.getText(); 
      input.setText(""); 
      stats.setText(""); 
      stats.append("Health: " + Health + "/" + MaxHealth + "\n"); 
      stats.append("Gold: " + Gold); 
     } 
    }); 
    send.setBounds(301, 224, 128, 32); 
    contentPane.add(send); 

    stats.append("Health: " + Health + "/" + MaxHealth + "\n"); 
    stats.append("Gold: " + Gold); 

} 

public static void game (JButton send, JTextArea console, JTextArea stats, JTextArea invintory, JTextField input, String i) { 




    //start 
    //START 
    //START 
    //START 
    //START 
    while (true) {   
     console.append("You wake up open feild, with vast amounts of wheet in every direction"); 
     console.append("There is a path going in either direction what do you want to do"); 
     console.append("\t1. Go left."); 
     console.append("\t2. Go right."); 
     while (i == "") { 
     } 
     if (i == "1") { 
      console.append("1"); 
      break; 
     } 
     else if (i == "2") { 
      console.append("2"); 
      break; 
     } 



    } 
    //END 
    //END 
    //END 
    //END 
    } 

public static void main(String[] args) { 
      try { 
       Gui frame = new Gui(); 
       frame.setVisible(true); 
       Gui.game(send, console, stats, invintory, input, i); 
      } catch (Exception e) { 
       e.printStackTrace(); 
      } 

     } 

} 

Answer 1

In Ihrem globalen Variablen console null ist

public static JTextArea console; 

Sie initialisiert es in Gui Methode

JTextArea console = new JTextArea(); 

Also hier in Gui Methode, um Ihre globalen console Variable ist nicht ich nitialized, Dies erstellt eine lokale Variable Konsole unter Gui Methode.

Um globale Variable in Gui-Methode müssen Sie initialisieren diese Weise auf alle Variablen so bearbeiten Sie den Code auf diese Weise

public Gui() { 
    //variables 

    int Gold = 20; 
    int Health = 100; 
    int MaxHealth = 100; 


    //variables end 
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    setBounds(100, 100, 450, 300); 
    contentPane = new JPanel(); 
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); 
    setContentPane(contentPane); 
    contentPane.setLayout(null); 

    console = new JTextArea(); 
    console.setBounds(10, 11, 281, 214); 
    contentPane.add(console); 

    input = new JTextField(); 
    input.setBounds(10, 236, 281, 20); 
    contentPane.add(input); 
    input.setColumns(10); 

    stats = new JTextArea(); 
    stats.setBounds(301, 11, 123, 53); 
    contentPane.add(stats); 

    invintory = new JTextArea(); 
    invintory.setBounds(301, 75, 128, 137); 
    contentPane.add(invintory); 

    send = new JButton("Send"); 
    send.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent arg0) { 
      String i = input.getText(); 
      input.setText(""); 
      stats.setText(""); 
      stats.append("Health: " + Health + "/" + MaxHealth + "\n"); 
      stats.append("Gold: " + Gold); 
     } 
    }); 
    send.setBounds(301, 224, 128, 32); 
    contentPane.add(send); 

    stats.append("Health: " + Health + "/" + MaxHealth + "\n"); 
    stats.append("Gold: " + Gold); 

    }