[英]How do I draw string from user input in a JFrame Java
無法從搜索功能中找到所需的內容,可能是標題的格式不正確。
無論如何,現在我可以單擊我的JFrame,它將把用戶輸入的內容繪制到控制台中 ,當您按Enter時,它將停止該句子。
但是我想要的是讓用戶直接在JFrame中鍵入內容,然后在按Enter鍵時結束輸入。
這就是我現在所擁有的:
public void drawString(MouseEvent e) throws IOException {
if(textClick==true) {
int xLoc = e.getX();
int yLoc = e.getY();
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String accStr;
System.out.println("Enter your Account number: ");
accStr = br.readLine();
g2.drawString(accStr, xLoc, yLoc);
textClick=false;
}
}
因此,您單擊JFrame上的某個位置。 然后,它將顯示用戶在該位置鍵入的任何內容,而無需進入控制台並在那里鍵入。
不要將控制台輸入與Swing GUI混合使用,因為這可能導致線程惡夢。 而是通過其他方式獲取輸入。 我本人將使用JOptionPane.showInputDialog(...)
獲取用戶的輸入String。 另外,不要像在paint或paintComponent方法之外一樣使用Graphics,因為這是NullPointerException或其他GUI失敗的秘訣。 而是在JLabel或文本組件(例如JTextArea或JTextField)中顯示文本。
就像是:
public void drawString(MouseEvent e) throws IOException {
if(textClick) { // none of this == true stuff please
int xLoc = e.getX();
int yLoc = e.getY();
String prompt = "Enter your Account Number:";
String input = JOptionPane.showInputDialog(someComponent, prompt);
// !!! no
// g2.drawString(accStr, xLoc, yLoc); // no don't do this
myJLabel.setText(input);
textClick=false;
}
}
如果您絕對必須使用Graphics繪制String,則在上面的方法中,設置對象的字段,也許像private String textToDraw
,在GUI上以及JPanel protected void paintComponent(Graphics g)
方法中調用repaint()
。繪制文本。
這是一個合並代碼,將JTextField放在鼠標按下的位置,然后在按Enter鍵或失去焦點時將JTextField轉換為JLabel:
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
public class AddingText extends JPanel {
private static final int PREF_W = 500;
private static final int PREF_H = PREF_W;
public AddingText() {
addMouseListener(new MyMouse());
setLayout(null); // one of the few times this may be ok
}
@Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
private void convertToLabel(final JTextField textField) {
JLabel label = new JLabel(textField.getText());
label.setSize(label.getPreferredSize());
label.setLocation(textField.getLocation());
remove(textField);
add(label);
repaint();
}
private class MyMouse extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
final JTextField textField = new JTextField(20);
textField.setSize(textField.getPreferredSize());
textField.setLocation(e.getPoint());
add(textField);
revalidate();
repaint();
textField.requestFocusInWindow();
textField.addFocusListener(new FocusAdapter() {
@Override
public void focusLost(FocusEvent e) {
convertToLabel((JTextField) e.getComponent());
}
});
textField.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
convertToLabel((JTextField) e.getSource());
}
});
}
}
private static void createAndShowGui() {
AddingText mainPanel = new AddingText();
JFrame frame = new JFrame("AddingText");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
嘗試兩個:通過覆蓋paintComponent和使用JOptionPane直接在JPanel中繪制。 將該文本放入Map<Point, String>
,然后通過遍歷此地圖在paintComponent中繪制此文本。 這樣,我們避免了可怕的null
布局。
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.swing.*;
public class AddingText2 extends JPanel {
private static final int PREF_W = 500;
private static final int PREF_H = PREF_W;
private Map<Point, String> pointTextMap = new LinkedHashMap<>();
public AddingText2() {
addMouseListener(new MyMouse());
}
@Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setFont(getFont().deriveFont(Font.BOLD));
for (Point p : pointTextMap.keySet()) {
String text = pointTextMap.get(p);
g.drawString(text, p.x, p.y);
}
}
private class MyMouse extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
String prompt = "Please add text to display";
String input = JOptionPane.showInputDialog(AddingText2.this, prompt);
pointTextMap.put(e.getPoint(), input);
repaint();
}
}
private static void createAndShowGui() {
AddingText2 mainPanel = new AddingText2();
JFrame frame = new JFrame("AddingText2");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
如果我正確理解您的問題,那么您基本上需要一個KeyListener
:
public class MyWindow extends JFrame {
private int x, y;
private String text;
private boolean shouldGetText = false;
private KeyListener keyboard = new KeyAdapter() {
public void keyTyped(KeyEvent evt) {
if(!shouldGetText)
return;
text = text + evt.getChar(); // or evt.getKeyChar()... not sure about the name of this method
}
public void keyPressed(KeyEvent evt) {
if (shouldGetText && evt.getKeyCode() == KeyEvent.VK_ENTER)
shouldGetText = false;
}
}
private MouseListener mouse = new MouseAdapter() {
public void mouseMoved(MouseEvent evt) {
if (shouldGetText)
return;
x = evt.getX();
y = evt.getY();
}
public void mousePressed(MouseEvent evt) {
shouldGetText = true;
text = "";
}
}
public MyWindow() {
addKeyListener(keyboard);
addMouseListener(mouse);
addMouseMotionListene(mouse);
// Do other stuff
}
@Override
public void paint(Graphics g) {
super.paint(g);
g.drawString(text, x, y);
}
}
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