您好，在创建动态 textArea 方法时，我返回了
Exception in thread "main" java.lang.NullPointerException
at WindowCreation.setContentsParams(WindowCreation.java:121)
at Main.main(Main.java:38)
我需要能够返回用户输入并将其发送到数据库中，但目前我只是试图获取单个 textField/textArea ID 以便能够从它们返回文本
WindowCreation 类如下
import javax.swing.*;
import javax.swing.event.DocumentListener;
import java.awt.*;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
public class WindowCreation {
private int mainHeight = 0;
private int mainWidth = 0;
private JButton button;
private ArrayList<JTextField> textField;
private ArrayList<JTextArea> textArea;
private JLabel label;
private JFrame frame;
private Toolkit tk = Toolkit.getDefaultToolkit();
private Dimension screenSize = tk.getScreenSize();
private JPanel jlabelEmpty = new JPanel();
private DefaultComboBoxModel<String> model;
private JComboBox<String> comboBox;
public void setWindowParam(int width, int height, String name, int x,
int y, boolean center) {
frame = new JFrame(name);
int screenHeight = screenSize.height;
int screenWidth = screenSize.width;
final int CENTER_X = ((screenWidth / 2) - (width / 2));
final int CENTER_Y = ((screenHeight / 2) - (height / 2));
frame.setResizable(false);
if (center) {
frame.setLocation(CENTER_X, CENTER_Y);
} else {
frame.setLocation(x, y);
}
frame.setSize(width, height);
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
jlabelEmpty.setPreferredSize(new Dimension(width, height));
jlabelEmpty.setOpaque(true);
jlabelEmpty.setLayout(null);
mainWidth = width;
mainHeight = height;
}
public void setContentsParams(int width, int height, String x, String y,
String content, String type,String[] choice) {
boolean xIsNum;
int wdthOffset;
boolean yIsNum;
int hightOffset;
try {
Integer.parseInt(x);
xIsNum = true;
} catch (Exception e) {
xIsNum = false;
}
if (x.equals("center")) {
wdthOffset = ((getWidth() / 2) - (width / 2));
} else if (xIsNum) {
wdthOffset = Integer.parseInt(x);
}else{
wdthOffset = 0;
}
try {
Integer.parseInt(y);
yIsNum = true;
} catch (Exception e) {
yIsNum = false;
}
if (y.equals("center")) {
hightOffset = ((getHeight() / 2) - (height / 2));
} else if (yIsNum) {
hightOffset = Integer.parseInt(y);
}else{
hightOffset = 0;
}
switch (type) {
case "button":
button = new JButton(content);
button.setSize(new Dimension(width, height));
button.setLocation(wdthOffset, hightOffset);
jlabelEmpty.add(button);
button.setFont(new Font("name1", Font.BOLD, 20));
ActionListener buttonListener = new ButtonListener();
button.addActionListener(buttonListener);
break;
case "textfield":
textField.add(new JTextField(content));
textField.get(textField.size()-1).setSize(new Dimension (width,height));
textField.get(textField.size()-1).setLocation(wdthOffset, hightOffset);
jlabelEmpty.add(textField.get(textField.size()-1));
break;
case "textarea":
textArea.add(new JTextArea(content));
textArea.get(textArea.size()-1).setSize(new Dimension(width,height));
textArea.get(textArea.size()-1).setLocation(wdthOffset, hightOffset);
jlabelEmpty.add(textArea.get(textArea.size()-1));
break;
case "textdisplay":
label = new JLabel(content);
label.setSize(new Dimension(width,height));
label.setLocation(wdthOffset, hightOffset);
jlabelEmpty.add(label);
break;
case "dropmenu":
model = new DefaultComboBoxModel<String>();
int i = 0;
while (i < choice.length){
model.addElement(choice[i]);
i++;
}
comboBox = new JComboBox<String>(model);
comboBox.setSize(new Dimension(width,height));
comboBox.setLocation(wdthOffset,hightOffset);
jlabelEmpty.add(comboBox);
}
frame.revalidate();
frame.repaint();
}
public void displayInput(int compNum){
System.out.println(textArea.get(compNum));
}
public void removePanel(int panel){
jlabelEmpty.remove(panel);
}
public int getWidth() {
return (mainWidth);
}
public int getHeight() {
return (mainHeight);
}
public void DisplayWindow() {
frame.getContentPane().add(jlabelEmpty, BorderLayout.CENTER);
frame.pack();
frame.setVisible(true);
}
}
以及调用它的方法
st = con.createStatement();
ResultSet rs = st.executeQuery("select * from HR.employees");
System.out.println("attempting to import Table...");
window.removePanel(0);
window.setContentsParams(200, 30, "center", "101", "First Name", "textarea",null);
window.setContentsParams(200, 30, "center", "131", "Last Name", "textfield",null);
window.setContentsParams(200, 30, "center", "161", "Email", "textfield",null);
window.setContentsParams(200, 30, "center", "191", "PhoneNumber", "textfield",null);
window.setContentsParams(200, 30, "center", "221", "Start Date", "textfield",null);
String[] position = {"AD_PRES","AD_VP","AD_ASST","FI_MGR","FI_ACCOUNT","SA_MAN","SA_REP","PU_MAN","PU_MAN","PU_CLERK","ST_MAN","SH_CLERK","IT_PROG","MK_MAN","MK_REP","HR_REP","PR_REP"};
window.setContentsParams(200, 30, "center", "251", "position", "dropmenu",position);
window.setContentsParams(200, 30, "center", "281", "Salary (Yearly)", "textfield",null);
String[] managerCodes = {"100","103","108","114","121","145","200","201","203","204","205"};
window.setContentsParams(200, 30, "center", "311", "Manager Number", "dropmenu",managerCodes);
String[] departmentCode = {"10","20","30","40","50","60","70","80","90","100","110","120","130","140","150","160","170","180","190","200","210","220","230","240","250","260","270"};
window.setContentsParams(200, 30, "center", "341", "Department ID", "dropmenu",departmentCode);
window.setContentsParams(100, 1000, "center", "541", "confirm", "button", null);
while (rs.next()) {
String outputTable = String
.format("%-6s | %-11s | %-11s | %-9s | %-18s | %-14s | %-10s | %-7s | %-4s | %-4s | %-4s ",
rs.getString("EMPLOYEE_ID"),
rs.getString("FIRST_NAME"),
rs.getString("LAST_NAME"),
rs.getString("EMAIL"),
rs.getString("PHONE_NUMBER"),
rs.getString("HIRE_DATE"),
rs.getString("JOB_ID"), rs.getString("SALARY"),
rs.getString("COMMISSION_PCT"),
rs.getString("MANAGER_ID"),
rs.getString("DEPARTMENT_ID"));
System.out.println(outputTable);
}
如果我不使用和数组来识别文本字段，它工作正常，但是我无法获取单个字段的输入