为什么在引用其他类中的复选框时会出现空指针异常？这是因为我必须使CheckBox以图形方式显示，以使它们不是null吗？
这是错误：
线程中的异常“AWT-EventQueue-0”java.lang.NullPointerException
在 com.company.Output.Constraint.removePersonWithConstraint1（Constraint.java:125）
和第125行位于System.out.println(inputChange.wk1.isSelected());
removePersonWithConstraint1()行
package com.company.Output;
import com.company.Input.Input;
import com.company.Input.InputChange;
import com.company.Input.InputMain;
import java.time.Month;
import java.time.Year;
import java.util.ArrayList;
import java.util.Calendar;
/**
* Created by paull on 6/6/2016.
*/
public class Constraint {
Input input;
DateRange dateRange;
Output output;
InputMain inputMain;
InputChange inputChange;
Calendar calendar;
ArrayList<String> listOfFirstSundays;
ArrayList<String> listOfSecondSundays;
ArrayList<String> listOfThirdSundays;
ArrayList<String> listOfFourthSundays;
ArrayList<String> listOfFifthSundays;
public Constraint(Input input, DateRange dateRange,Output output,InputMain inputMain,InputChange inputChange) {
this.input = input;
this.dateRange = dateRange;
this.output = output;
this.inputMain = inputMain;
this.inputChange = inputChange;
listOfFirstSundays = new ArrayList<String>();
listOfSecondSundays = new ArrayList<String>();
listOfThirdSundays = new ArrayList<String>();
listOfFourthSundays = new ArrayList<String>();
listOfFifthSundays = new ArrayList<String>();
calendar = Calendar.getInstance();
}
public void constraint1(int year, int month) {
calendar.set(year,month - 1,1);
int monthDays = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
int monthlySundayCounter = 0;
String ithSunday = "";
for (int i = 1; i <= monthDays; i++) {
calendar.set(year,month - 1,i);
int day = calendar.get(Calendar.DAY_OF_WEEK);
String dayString = year + "/" + month + "/" + i; //setup the daystring
//System.out.println(dayString);
if (day == Calendar.SUNDAY) {
monthlySundayCounter++;//count which sunday it is in a month
//System.out.println(year + "/" + month + "/" + i + " is the " + monthlySundayCounter + " th Sunday."); //this line works
for (int j = 0; j < output.dtm.getRowCount(); j++) {
//test
//System.out.println(output.tableResult.getValueAt(j,0));
//System.out.println("dayString = " + dayString);
//System.out.println("output at " + j + "row and 0 column = " + output.tableResult.getValueAt(j,0));
//System.out.println(output.tableResult.getValueAt(j,0).equals(dayString));
if (output.tableResult.getValueAt(j,0).equals(dayString)) {
//System.out.println("this works");
switch (monthlySundayCounter) {
case 1:
listOfFirstSundays.add(dayString);
//System.out.println(dayString + " is the 1st Sunday.");
break;
case 2:
listOfSecondSundays.add(dayString);
//System.out.println(dayString + " is the 2nd Sunday.");
break;
case 3:
listOfThirdSundays.add(dayString);
//System.out.println(dayString + " is the 3rd Sunday.");
break;
case 4:
listOfFourthSundays.add(dayString);
//System.out.println(dayString + " is the 4th Sunday.");
break;
case 5:
listOfFifthSundays.add(dayString);
//System.out.println(dayString + " is the 5th Sunday.");
break;
}
}
}
}
}
}
public void removePersonWithConstraint1() {
//for each person within the inputmain table
//1. setCheckboxBasedOnConstraintText()
//if (checkbox is checked for nth Sunday), then {delete him from every list (list of sat, list of eight, etc.) for that Sunday}
for (int i = 0; i < inputMain.model.getRowCount(); i++) { //for each row within the inputmain table
//reset all the checkboxes
System.out.println(inputChange.wk1.isSelected());
System.out.println(inputChange.wk2.isSelected());
System.out.println(inputChange.wk3.isSelected());
System.out.println(inputChange.wk4.isSelected());
System.out.println(inputChange.wk5.isSelected());
inputChange.wk1.setSelected(false);
inputChange.wk2.setSelected(false);
inputChange.wk3.setSelected(false);
inputChange.wk4.setSelected(false);
inputChange.wk5.setSelected(false);
inputMain.setCheckboxBasedOnConstraintText(i); //set the checkbox based on the constraint text
System.out.println(inputChange.wk1.isSelected());
System.out.println(inputChange.wk2.isSelected());
System.out.println(inputChange.wk3.isSelected());
System.out.println(inputChange.wk4.isSelected());
System.out.println(inputChange.wk5.isSelected());
String name = inputMain.table.getValueAt(i,0).toString();//get the name of that person from inputmain
System.out.println(name);
if (inputChange.wk1.isSelected()) { //if the checkbox is checked
System.out.println(inputChange.wk1.isSelected());
for (int j = 0; j < output.dtm.getRowCount(); j++) {
for (String lofs : listOfFirstSundays) { //for every sunday within listoffirstsunday, if it equals to a sunday in the output tableresult
if (lofs.equals(output.tableResult.getValueAt(j, 0).toString())) {
System.out.println(lofs);
System.out.println(output.tableResult.getValueAt(j,0).toString());
//remove the person who chose that constraint
output.tableResult.getValueAt(j,0).toString().replaceAll((name),""); //(name) is a regular expression
}
}
}
}
if (inputChange.wk2.isSelected()) { //if the checkbox is checked
for (int j = 0; j < output.dtm.getRowCount(); j++) {
for (String lofs : listOfSecondSundays) { //for every sunday within listoffirstsunday, if it equals to a sunday in the output tableresult
if (lofs.equals(output.tableResult.getValueAt(j, 0).toString())) {
System.out.println(lofs);
System.out.println(output.tableResult.getValueAt(j,0).toString());
//remove the person who chose that constraint
output.tableResult.getValueAt(j,0).toString().replaceAll((name),""); //(name) is a regular expression
}
}
}
}
if (inputChange.wk3.isSelected()) { //if the checkbox is checked
for (int j = 0; j < output.dtm.getRowCount(); j++) {
for (String lofs : listOfThirdSundays) { //for every sunday within listoffirstsunday, if it equals to a sunday in the output tableresult
if (lofs.equals(output.tableResult.getValueAt(j, 0).toString())) {
System.out.println(lofs);
System.out.println(output.tableResult.getValueAt(j,0).toString());
//remove the person who chose that constraint
output.tableResult.getValueAt(j,0).toString().replaceAll((name),""); //(name) is a regular expression
}
}
}
}
if (inputChange.wk4.isSelected()) { //if the checkbox is checked
for (int j = 0; j < output.dtm.getRowCount(); j++) {
for (String lofs : listOfFourthSundays) { //for every sunday within listoffirstsunday, if it equals to a sunday in the output tableresult
if (lofs.equals(output.tableResult.getValueAt(j, 0).toString())) {
System.out.println(lofs);
System.out.println(output.tableResult.getValueAt(j,0).toString());
//remove the person who chose that constraint
output.tableResult.getValueAt(j,0).toString().replaceAll((name),""); //(name) is a regular expression
}
}
}
}
if (inputChange.wk5.isSelected()) { //if the checkbox is checked
for (int j = 0; j < output.dtm.getRowCount(); j++) {
for (String lofs : listOfFifthSundays) { //for every sunday within listoffirstsunday, if it equals to a sunday in the output tableresult
if (lofs.equals(output.tableResult.getValueAt(j, 0).toString())) {
System.out.println(lofs);
System.out.println(output.tableResult.getValueAt(j,0).toString());
//remove the person who chose that constraint
output.tableResult.getValueAt(j,0).toString().replaceAll((name),""); //(name) is a regular expression
}
}
}
}
}
}
}
按要求输入InputChange。我认为复选框已初始化。
package com.company.Input;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/**
* Created by paull on 6/6/2016.
*/
public class InputChange {
JLabel nameLabel;
JLabel optionLabel;
JLabel constraintLabel;
JButton enter;
JPanel labelPanel;
JPanel jp2;
JPanel jp3;
JPanel jp4;
JTextField nameText;
String[] optionStrings;
JComboBox<String> optionText;
public JCheckBox wk1;
public JCheckBox wk2;
public JCheckBox wk3;
public JCheckBox wk4;
public JCheckBox wk5;
String constraintText;
JPanel checkboxPanel;
private InputMain im;
public InputChange(InputMain inputMain) {
this.im = inputMain;
nameLabel = new JLabel("");
optionLabel = new JLabel("");
constraintLabel = new JLabel("");
enter = new JButton("");
nameText = new JTextField(10);
Options c = new Options();
optionStrings = new String[]{c.satNight,c.sunEight,c.sunNineThirty,c.sunEleven,c.sunNight};
optionText = new JComboBox<String>(optionStrings);
wk1 = new JCheckBox("");
wk2 = new JCheckBox("");
wk3 = new JCheckBox("");
wk4 = new JCheckBox("");
wk5 = new JCheckBox("");
constraintText = new String();
checkboxPanel = new JPanel(new FlowLayout(10,30,10));
int fontSize = 50;
nameLabel.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
optionLabel.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
constraintLabel.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
enter.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
nameText.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
optionText.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
wk1.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
wk2.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
wk3.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
wk4.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
wk5.setFont(new Font(nameLabel.getName(),Font.PLAIN,fontSize));
//Image ticked = Toolkit.getDefaultToolkit().getImage("Ticked.png");
//Image unticked = ImageIO.s("Unticked.png");
ImageIcon unticked = new ImageIcon(getClass().getResource("Unticked.png"));
Image utimg = unticked.getImage();
//Icon tickedIcon = new ImageIcon(ticked.getScaledInstance(100,100, Image.SCALE_DEFAULT));
Icon untickedIcon = new ImageIcon(utimg.getScaledInstance(50,50, Image.SCALE_DEFAULT));
ImageIcon ticked = new ImageIcon(getClass().getResource("Ticked.png"));
Image timg = ticked.getImage();
Icon tickedIcon = new ImageIcon(timg.getScaledInstance(50,50,Image.SCALE_DEFAULT));
wk1.setIcon(untickedIcon);
wk2.setIcon(untickedIcon);
wk3.setIcon(untickedIcon);
wk4.setIcon(untickedIcon);
wk5.setIcon(untickedIcon);
wk1.setSelectedIcon(tickedIcon);
wk2.setSelectedIcon(tickedIcon);
wk3.setSelectedIcon(tickedIcon);
wk4.setSelectedIcon(tickedIcon);
wk5.setSelectedIcon(tickedIcon);
checkboxPanel.add(wk1);
checkboxPanel.add(wk2);
checkboxPanel.add(wk3);
checkboxPanel.add(wk4);
checkboxPanel.add(wk5);
JPanel namePanel = new JPanel(new FlowLayout(10,30,10));
namePanel.add(nameLabel);
namePanel.add(nameText);
JPanel optionPanel = new JPanel(new FlowLayout(10,30,10));
optionPanel.add(optionLabel);
optionPanel.add(optionText);
JPanel constraintPanel = new JPanel(new FlowLayout(10,30,0));
constraintPanel.add(constraintLabel);
constraintPanel.add(checkboxPanel);
labelPanel = new JPanel();
labelPanel.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.FIRST_LINE_START;//Start everythin from the top
gbc.anchor = GridBagConstraints.CENTER;//place everything in the center
gbc.weightx = 0.25;
gbc.weighty = 0.5;
gbc.gridx = 0;
gbc.gridy = 0;
labelPanel.add(nameLabel,gbc);
gbc.weighty = 0.5;
gbc.gridx = 1;
gbc.gridy = 0;
labelPanel.add(nameText,gbc);
gbc.weighty = 0.5;
gbc.gridx = 0;
gbc.gridy = 1;
labelPanel.add(optionLabel,gbc);
gbc.weighty = 0.5;
gbc.gridx = 1;
gbc.gridy = 1;
labelPanel.add(optionText,gbc);
gbc.weightx = 10;
gbc.weighty = 0.5;
gbc.gridx = 0;
gbc.gridy = 2;
labelPanel.add(constraintLabel,gbc);
gbc.weightx = 1.5;
gbc.weighty = 0.5;
gbc.gridx = 1;
gbc.gridy = 2;
labelPanel.add(checkboxPanel,gbc);
gbc.weighty = 0.5;
gbc.gridx = 1;
gbc.gridy = 3;
labelPanel.add(enter,gbc);
// InputMain i = new InputMain();
//inputMain.table.setModel(new DefaultTableModel(null,inputMain.columns));//i.data,i.columns --> defaulttablemodel is defined in inputMain.java
DefaultTableModel model = (DefaultTableModel) inputMain.table.getModel();
enter.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
setConstraintText();
String[] data = new String[]{nameText.getText(),optionText.getSelectedItem().toString(),constraintText};
model.addRow(data);
nameText.setText("");
wk1.setSelected(false);//To clear out the previous checkboxes
wk2.setSelected(false);
wk3.setSelected(false);
wk4.setSelected(false);
wk5.setSelected(false);
}
});
}
这是我创建约束实例的地方，并调用了constranint：
package com.company.Output;
//import com.company.Input.InputMain;
import com.company.Input.Input;
import com.company.Input.InputChange;
import com.company.Input.InputMain;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Calendar;
/**
* Created by paull on 29/5/2016.
*/
public class DateRange {
JLabel topic;
JLabel year1;
JLabel month1;
JLabel day1;
JLabel till;
JLabel year2;
JLabel month2;
JLabel day2;
JTextField beginYear;
JTextField beginMonth;
JTextField beginDay;
JTextField endYear;
JTextField endMonth;
JTextField endDay;
JButton confirm;
JPanel words;
public JPanel pane;
Calendar calendar;
int beginYearInt;
int beginMonthInt;
int beginDayInt;
int endYearInt;
int endMonthInt;
int endDayInt;
Output op;
private InputMain im;
Input input;
InputChange inputChange;
Constraint constraint;
public DateRange(InputMain im, Input input, InputChange inputChange) {
topic = new JLabel("");
year1 = new JLabel("");
month1 = new JLabel("");
day1 = new JLabel("");
till = new JLabel("");
year2 = new JLabel("");
month2 = new JLabel("");
day2 = new JLabel("");
beginYear = new JTextField(3);
beginMonth = new JTextField(2);
beginDay = new JTextField(2);
endYear = new JTextField(3);
endMonth = new JTextField(2);
endDay = new JTextField(2);
confirm = new JButton("");
words = new JPanel(new FlowLayout(3,10,3));
pane = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.FIRST_LINE_START;
gbc.anchor = GridBagConstraints.CENTER;
gbc.weighty = 1;//vertical axis ratio
gbc.gridx = 0;//which goes first starts from left;integer
gbc.gridy = 0;//which goes first starts from top;integer
pane.add(topic,gbc);
gbc.weighty = 1;//vertical axis ratio
gbc.gridx = 0;//which goes first starts from left;integer
gbc.gridy = 1;//which goes first starts from top;integer
words.add(beginYear);
words.add(year1);
words.add(beginMonth);
words.add(month1);
words.add(beginDay);
words.add(day1);
words.add(till);
words.add(endYear);
words.add(year2);
words.add(endMonth);
words.add(month2);
words.add(endDay);
words.add(day2);
pane.add(words,gbc);
gbc.weighty = 1;//vertical axis ratio
gbc.gridx = 0;//which goes first starts from left;integer
gbc.gridy = 2;//which goes first starts from top;integer
pane.add(confirm,gbc);
int fontSize = 50;
topic.setFont(new Font(topic.getName(),Font.PLAIN,fontSize));
words.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
beginYear.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
year1.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
year2.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
beginMonth.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
month1.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
month2.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
beginDay.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
day1.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
day2.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
till.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
endYear.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
endMonth.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
endDay.setFont(new Font(words.getName(),Font.PLAIN,fontSize));
confirm.setFont(new Font(confirm.getName(),Font.PLAIN,fontSize));
calendar = Calendar.getInstance();
//addColumnConfirmListener(2010,6,1);
//datesOfSundaysInTheSameMonth();
confirmActionListener();
//datesOfSundaysInTheBeginningMonth();
//datesOfSundaysInTheEndingMonth();
this.im = im;
//im = new InputMain();
op = new Output(im);
this.input = input;
constraint = new Constraint(input,this,op,im,inputChange);
}
public void datesUsingIndicator() {
//parse those integers immediately after clicking the confirm button
beginYearInt = parseIntWithException(beginYear,-1);//Integer.parseInt(beginYear.getText()) ;
beginMonthInt = parseIntWithException(beginMonth,-1);//Integer.parseInt(beginMonth.getText());
beginDayInt = parseIntWithException(beginDay,-1);//Integer.parseInt(beginDay.getText());
endYearInt = parseIntWithException(endYear,-1);//Integer.parseInt(endYear.getText());
endMonthInt = parseIntWithException(endMonth,-1);//Integer.parseInt(endMonth.getText());
endDayInt = parseIntWithException(endDay,-1);//Integer.parseInt(endDay.getText());
int noOfMonths = 0;
if (beginYearInt == endYearInt) { // for the case of same year
//THIS PART WORKS PERFECT
for (int i = beginMonthInt; i <= endMonthInt; i++) {
noOfMonths++;
}
if (noOfMonths >= 3) {
datesOfSundaysInTheBeginningMonth();
for (int i = beginMonthInt + 1; i < endMonthInt; i++) {
datesOfSundaysInTheMiddleMonths(endYearInt,i);
}
datesOfSundaysInTheEndingMonth();
}
if (noOfMonths == 2) {
datesOfSundaysInTheBeginningMonth();
datesOfSundaysInTheEndingMonth();
}
if (noOfMonths == 1) {
datesOfSundaysInTheSameMonth();
}
}
if (beginYearInt != endYearInt){ //for the case of different year
int noOfYears = 0;
for (int i = beginYearInt; i <= endYearInt; i++) {
noOfYears++;
}
//calcualtion of sundays start from here:
datesOfSundaysInTheBeginningMonth(); //Till the end of first month
int beginyrmonthcounter = beginMonthInt + 1; // starts from the second month
while (beginyrmonthcounter <= 12) {
datesOfSundaysInTheMiddleMonths(beginYearInt,beginyrmonthcounter); //2nd month till December
beginyrmonthcounter++;
} //first year ended
if (noOfYears >= 3) {//this case only happens if number of years is larger than or equal to 3
for (int i = beginYearInt + 1; i <= endYearInt - 1; i++) { //second year till the second last year
for (int j = 1; j <= 12; j++) { //from jan till december
datesOfSundaysInTheMiddleMonths(i, j);
}
}
}
int endyrmonthcounter = 1;
while (endyrmonthcounter < endMonthInt) { //from january of last year till the month before endmonth
datesOfSundaysInTheMiddleMonths(endYearInt,endyrmonthcounter);
endyrmonthcounter++;
}
datesOfSundaysInTheEndingMonth();
}
}
public void confirmActionListener() { //just enter the actual month. The functions already -1ed the month for calendar
confirm.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
//create an output frame
OutputFrame of = new OutputFrame();
of.add(op.outPanel);
op.topic3.setText(beginYear.getText() + "/" + beginMonth.getText() + "/" + beginDay.getText() + " - "
+ endYear.getText() + "/" + endMonth.getText() + "/" + endDay.getText());
//remove all the previous data in case the user clicks the confirm button once more time
for (int i = op.tableResult.getRowCount()-1; i >= 0; i--) {
op.dtm.removeRow(i);
}
for (int i = im.listOfSat.size() - 1; i >= 0; i--) {
im.listOfSat.remove(i);
}
for (int i = im.listOfEight.size() - 1; i >= 0; i--) {
im.listOfEight.remove(i);
}
for (int i = im.listOfNineThirty.size() - 1; i >= 0; i--) {
im.listOfNineThirty.remove(i);
}
for (int i = im.listOfEleven.size() - 1; i >= 0; i--) {
im.listOfEleven.remove(i);
}
for (int i = im.listOfSunSix.size() - 1; i >= 0; i--) {
im.listOfSunSix.remove(i);
}
datesUsingIndicator();
im.addPersonToCorrectQueue();
//TODO: removePersonWithConstraint1();
//op.setToCorrectTimetableSlot();
im.resetEveryTwoWeeksAndSetToCorrectTimeSlot(op);
constraint.removePersonWithConstraint1();
of.setVisible(true);
}
});
}
}