[英]Changing text on a JLabel from another class
因此,我一直在試圖弄清楚這一點,卻無法弄清楚如何做到這一點。 我希望另一個類中的按鈕之一可以更改GUI類中JLabel的文本。
這是來自GUI類的代碼:`import java.awt.Container;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
public class GUI extends JFrame{
Container pane = getContentPane();
JButton guess = new JButton("Guess");
JButton gen = new JButton("Generate number");
JTextField userInput = new JTextField();
JLabel Numbers = new JLabel("Press generate to start.");
JLabel guessedNum = new JLabel("");
JLabel error = new JLabel("");
public void CreateGUI(){
final int WIDTH = 325;
final int HEIGHT = 200;
final int centerWIDTH = WIDTH / 4;
final int centerHEIGHT = HEIGHT / 4;
guessHandler guessHandle;
genHandler genHandle;
pane.setLayout(null);
guessHandle = new guessHandler();
guess.addActionListener(guessHandle);
genHandle = new genHandler();
gen.addActionListener(genHandle);
userInput.setBounds(centerWIDTH - 20, centerHEIGHT, 200, 20);
guess.setBounds(userInput.getX() - 35, (userInput.getY() + 25), 105, 50);
gen.setBounds((guess.getX() + 105), guess.getY(), 165, 50);
error.setBounds(70, 125, 300, 20);
Numbers.setBounds(90, 0, 300, 20);
guessedNum.setBounds(20, 25, 300, 20);
pane.add(userInput);
pane.add(guess);
pane.add(gen);
pane.add(Numbers);
pane.add(guessedNum);
pane.add(error);
setSize(WIDTH,HEIGHT);
setTitle("Number Guesser");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
setResizable(false);
setLocation(350, 150);
}
}
在這里,來自按鈕的代碼試圖更改JLabel“錯誤”:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;
public class guessHandler implements ActionListener{
public void actionPerformed(ActionEvent e) {
GUI gui = new GUI();
gui.changePOS(4, 50, 0, 300, 20);
gui.error.setText("HI from guessHandler.java");
}
}
首先,添加具有public
訪問權限的吸氣劑,以便您的第二堂課可以訪問該字段。 就像是,
public JLabel getError() {
return error;
}
或者(如@MadProgrammer在評論中建議的,是一個變種器),例如
public void setError(String txt) {
error.setText(txt);
}
然后修改第二個類,並在構造函數中將GUI
的實例傳遞給它。 喜歡,
public class guessHandler implements ActionListener{
private GUI gui;
public guessHandler(GUI gui) {
this.gui = gui;
}
public void actionPerformed(ActionEvent e) {
gui.changePOS(4, 50, 0, 300, 20);
gui.setError("HI from guessHandler.java");
}
}
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