如何从以前的创建中删除 JLabel？
How do i delete the JLabel from previous creation?
我正在创建一个日历，我使用 forloop 来循环日期并根据每一天添加 JLabel。但是，每当我更改日历的月份时，假设一月有 31 天，例如，如果我将月份更改为二月，二月将有 31 + 28 天，我真的很困惑如何解决这个问题
代码如下：
MonthPanel.java
public class MonthPanel extends JPanel {
private String[] headers = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
private int realDay, realMonth, realYear, currentMonth, currentYear;
private Toolbar toolbar;
private String inputTotal = "";
public MonthPanel() throws IOException {
setLayout(new GridLayout(6,7));
for (String header : headers) {
add(new JLabel(header));
}
changeCalendar();
}
public void changeCalendar(int month) throws IOException {
String[] months = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
int noDays, monthStart;
Border border = BorderFactory.createLineBorder(Color.BLACK, 1);
GregorianCalendar cal = new GregorianCalendar(2015, month, 1);
noDays = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
monthStart = cal.get(GregorianCalendar.DAY_OF_WEEK);
for(int i=1; i<= noDays; i++) {
JLabel label = new JLabel(String.valueOf(i));
label.setBackground(Color.WHITE);
label.setBorder(border);
label.setOpaque(true);
add(label);
}
System.out.println(months[month]);
System.out.println(noDays);
}
Toolbar.java
public class Toolbar extends JPanel {
public JComboBox<Object> months;
public JLabel monthName;
private JLabel pictureName;
private MonthListener monthListener;
public Toolbar() throws IOException {
ImageIcon img = new ImageIcon("/Users/naufal/Desktop/pictureC2.jpg");
pictureName = new JLabel(img);
String[] monthsList = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
months = new JComboBox<Object>(monthsList);
monthName = new JLabel(monthsList[0]);
setLayout(new FlowLayout());
add(months);
add(monthName);
add(pictureName);
}
MainFrame.java - 这是发生变化的地方，如果用户更改日历，它将发生变化
public class MainFrame extends JFrame {
private Toolbar toolBar;
private MonthPanel monthPanel;
String[] monthsList = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
public MainFrame() throws IOException {
super("Calendar App");
setLayout(new BorderLayout());
toolBar = new Toolbar();
monthPanel = new MonthPanel();
JComboBox getMonthBox = toolBar.getMonths();
ActionListener acListener = new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int monthIndex = getMonthBox.getSelectedIndex();
try {
monthPanel.changeCalendar(monthIndex);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
toolBar.monthName.setText(monthsList[boxCount]);
}
};
toolBar.months.addActionListener(acListener);
setSize(1200,900);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
add(toolBar, BorderLayout.NORTH);
add(monthPanel);
}
}
初始日历
在我将月份更改为二月之后，它附加了当前的 JLabel，即 31(January) JLabel 和另一个 28(February) JLabel
标签的父容器是什么？
您可以尝试重新绘制父容器上的标签。检查以下步骤以获取父对象并重新绘制它。当事件发生时使用它。我会把逻辑留给你。
Container parent = label.getParent();
parent.remove(label);
parent.validate();
parent.repaint();
作为替代方案，您可以实例化一个大小为 31 的 JLabels 数组，并使用 JPanel.remove() 删除从第 #noDays 天到第 #31 天的所有 JLabels , 并在必要时再次添加它们。
您甚至可以节省处理时间，因为您不必一直创建新的 JLabels，因为您正在回收它们。
MonthPanel 看起来像这样：
public class MonthPanel extends JPanel {
private String[] headers = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
private int realDay, realMonth, realYear, currentMonth, currentYear;
private Toolbar toolbar;
private String inputTotal = "";
private JLabel[] labelArray;
public MonthPanel() throws IOException {
setLayout(new GridLayout(6,7));
for (String header : headers) {
add(new JLabel(header));
}
Border border = BorderFactory.createLineBorder(Color.BLACK, 1);
/* Instantiate JLabel array */
labelArray = new JLabel[31];
for( int i = 0; i < 30; i++ ) {
JLabel label = new JLabel(""+(i+1));
label.setBackground(Color.WHITE);
label.setBorder(border);
label.setOpaque(true);
labelArray[i] = label;
}
changeCalendar();
}
public void changeCalendar(int month) throws IOException {
String[] months = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
int noDays, monthStart;
GregorianCalendar lastMonth = new GregorianCalendar(2015, month-1, 1);
noDaysLastMonth = lastMonth.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
GregorianCalendar cal = new GregorianCalendar(2015, month, 1);
noDays = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
monthStart = cal.get(GregorianCalendar.DAY_OF_WEEK);
if( noDaysLastMonth < noDays ) { // add days if this month has more days than last month
for( int i = noDaysLastMonth; i < noDays; i++ ) {
add( labelArray[i] );
}
}
else if ( noDays < noDaysLastMonth ) { // remove days if this month has less days than last month
for( int i = noDays; i < noDaysLastMonth; i++ ) {
remove( labelArray[i] );
}
}
validate();
repaint();
System.out.println(months[month]);
System.out.println(noDays);
}
尽管代码未经检查，但这就是逻辑。
我认为这可以完成您想要的工作。
如果您有任何疑问或不明白，请随时提问。
它是如何工作的，在代码中通过注释进行了描述。
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main extends JFrame implements ActionListener {
private JComboBox<String> months;
private String[] monthsList = { "January", "February", "March", "April",
"May", "June", "July", "August", "September", "October",
"November", "December" };
private JPanel panel;
private int[] days = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };// days
// of
// each
// month
public Main() {
super("My Caleander!");
months = new JComboBox<>(monthsList); // Adding months to Combo box.
panel = new JPanel(); // Panel for adding labels inside.
setLayout(new BorderLayout());
panel.setLayout(new GridLayout(0, 7));// 0 for dynamic number of rows
// and 7 for each week.
for (int i = 0; i < 31; i++) {
panel.add(new JLabel(String.valueOf(i + 1))); // Adding days of
// month January.
}
months.addActionListener(this);// Adding Action listener for responding
// to change of month.
add(months, BorderLayout.NORTH);
add(panel, BorderLayout.CENTER);
setVisible(true);
setLocationRelativeTo(null);// Putting JFrame to the center of screen.
setSize(300, 300);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new Main();
}
@Override
public void actionPerformed(ActionEvent e) {// Listening to changes made by
// ComboBox.
panel.removeAll();
int daysOfMonth = months.getSelectedIndex();// Getting the index of
// current month
for (int i = 0; i < days[daysOfMonth]; i++) {// Adding the requiered
// number of months.
panel.add(new JLabel(String.valueOf(i + 1)));
}
panel.revalidate();//Updating panel.
revalidate();//Upadating frame.
}
}
我正在创建一个日历，我使用 forloop 来循环日期并根据每一天添加 JLabel。但是，每当我更改日历的月份时，假设一月有 31 天，例如，如果我将月份更改为二月，二月将有 31 + 28 天，我真的很困惑如何解决这个问题
代码如下： MonthPanel.java
public class MonthPanel extends JPanel {
private String[] headers = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
private int realDay, realMonth, realYear, currentMonth, currentYear;
private Toolbar toolbar;
private String inputTotal = "";
public MonthPanel() throws IOException {
setLayout(new GridLayout(6,7));
for (String header : headers) {
add(new JLabel(header));
}
changeCalendar();
}
public void changeCalendar(int month) throws IOException {
String[] months = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
int noDays, monthStart;
Border border = BorderFactory.createLineBorder(Color.BLACK, 1);
GregorianCalendar cal = new GregorianCalendar(2015, month, 1);
noDays = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
monthStart = cal.get(GregorianCalendar.DAY_OF_WEEK);
for(int i=1; i<= noDays; i++) {
JLabel label = new JLabel(String.valueOf(i));
label.setBackground(Color.WHITE);
label.setBorder(border);
label.setOpaque(true);
add(label);
}
System.out.println(months[month]);
System.out.println(noDays);
}
Toolbar.java
public class Toolbar extends JPanel {
public JComboBox<Object> months;
public JLabel monthName;
private JLabel pictureName;
private MonthListener monthListener;
public Toolbar() throws IOException {
ImageIcon img = new ImageIcon("/Users/naufal/Desktop/pictureC2.jpg");
pictureName = new JLabel(img);
String[] monthsList = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
months = new JComboBox<Object>(monthsList);
monthName = new JLabel(monthsList[0]);
setLayout(new FlowLayout());
add(months);
add(monthName);
add(pictureName);
}
MainFrame.java - 这是发生变化的地方，如果用户更改日历，它将发生变化
public class MainFrame extends JFrame {
private Toolbar toolBar;
private MonthPanel monthPanel;
String[] monthsList = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
public MainFrame() throws IOException {
super("Calendar App");
setLayout(new BorderLayout());
toolBar = new Toolbar();
monthPanel = new MonthPanel();
JComboBox getMonthBox = toolBar.getMonths();
ActionListener acListener = new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int monthIndex = getMonthBox.getSelectedIndex();
try {
monthPanel.changeCalendar(monthIndex);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
toolBar.monthName.setText(monthsList[boxCount]);
}
};
toolBar.months.addActionListener(acListener);
setSize(1200,900);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
add(toolBar, BorderLayout.NORTH);
add(monthPanel);
}
}
初始日历
在我将月份更改为二月之后，它附加了当前的 JLabel，即 31(January) JLabel 和另一个 28(February) JLabel
标签的父容器是什么？
您可以尝试重新绘制父容器上的标签。检查以下步骤以获取父对象并重新绘制它。当事件发生时使用它。我会把逻辑留给你。
Container parent = label.getParent();
parent.remove(label);
parent.validate();
parent.repaint();
作为替代方案，您可以实例化一个大小为 31 的 JLabels 数组，并使用 JPanel.remove() 删除从第 #noDays 天到第 #31 天的所有 JLabels , 并在必要时再次添加它们。
您甚至可以节省处理时间，因为您不必一直创建新的 JLabels，因为您正在回收它们。
MonthPanel 看起来像这样：
public class MonthPanel extends JPanel {
private String[] headers = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
private int realDay, realMonth, realYear, currentMonth, currentYear;
private Toolbar toolbar;
private String inputTotal = "";
private JLabel[] labelArray;
public MonthPanel() throws IOException {
setLayout(new GridLayout(6,7));
for (String header : headers) {
add(new JLabel(header));
}
Border border = BorderFactory.createLineBorder(Color.BLACK, 1);
/* Instantiate JLabel array */
labelArray = new JLabel[31];
for( int i = 0; i < 30; i++ ) {
JLabel label = new JLabel(""+(i+1));
label.setBackground(Color.WHITE);
label.setBorder(border);
label.setOpaque(true);
labelArray[i] = label;
}
changeCalendar();
}
public void changeCalendar(int month) throws IOException {
String[] months = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
int noDays, monthStart;
GregorianCalendar lastMonth = new GregorianCalendar(2015, month-1, 1);
noDaysLastMonth = lastMonth.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
GregorianCalendar cal = new GregorianCalendar(2015, month, 1);
noDays = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH);
monthStart = cal.get(GregorianCalendar.DAY_OF_WEEK);
if( noDaysLastMonth < noDays ) { // add days if this month has more days than last month
for( int i = noDaysLastMonth; i < noDays; i++ ) {
add( labelArray[i] );
}
}
else if ( noDays < noDaysLastMonth ) { // remove days if this month has less days than last month
for( int i = noDays; i < noDaysLastMonth; i++ ) {
remove( labelArray[i] );
}
}
validate();
repaint();
System.out.println(months[month]);
System.out.println(noDays);
}
尽管代码未经检查，但这就是逻辑。
我认为这可以完成您想要的工作。
如果您有任何疑问或不明白，请随时提问。
它是如何工作的，在代码中通过注释进行了描述。
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main extends JFrame implements ActionListener {
private JComboBox<String> months;
private String[] monthsList = { "January", "February", "March", "April",
"May", "June", "July", "August", "September", "October",
"November", "December" };
private JPanel panel;
private int[] days = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };// days
// of
// each
// month
public Main() {
super("My Caleander!");
months = new JComboBox<>(monthsList); // Adding months to Combo box.
panel = new JPanel(); // Panel for adding labels inside.
setLayout(new BorderLayout());
panel.setLayout(new GridLayout(0, 7));// 0 for dynamic number of rows
// and 7 for each week.
for (int i = 0; i < 31; i++) {
panel.add(new JLabel(String.valueOf(i + 1))); // Adding days of
// month January.
}
months.addActionListener(this);// Adding Action listener for responding
// to change of month.
add(months, BorderLayout.NORTH);
add(panel, BorderLayout.CENTER);
setVisible(true);
setLocationRelativeTo(null);// Putting JFrame to the center of screen.
setSize(300, 300);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new Main();
}
@Override
public void actionPerformed(ActionEvent e) {// Listening to changes made by
// ComboBox.
panel.removeAll();
int daysOfMonth = months.getSelectedIndex();// Getting the index of
// current month
for (int i = 0; i < days[daysOfMonth]; i++) {// Adding the requiered
// number of months.
panel.add(new JLabel(String.valueOf(i + 1)));
}
panel.revalidate();//Updating panel.
revalidate();//Upadating frame.
}
}