Java ScrollPane(内部有一个TextArea)无法通过编程方式滚动到顶部
为了抽象这个问题,我设置了两个按钮。一个称为“添加和汇总”,另一个称为“汇总” 在最开始的文本区域中没有文本 我为“add&toTop”按钮添加了actionListener,如下所示:Java ScrollPane(内部有一个TextArea)无法通过编程方式滚动到顶部,java,swing,jscrollpane,jtextarea,Java,Swing,Jscrollpane,Jtextarea,为了抽象这个问题,我设置了两个按钮。一个称为“添加和汇总”,另一个称为“汇总” 在最开始的文本区域中没有文本 我为“add&toTop”按钮添加了actionListener,如下所示: btn1.addMouseListener(new MouseAdapter() { @Override public void mouseClicked(MouseEvent e) { textArea1.setText("jh
btn1.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
textArea1.setText("jhggjhg\nhugffsrdtfg\ngfdrtdf\nhgftrsdf\nytfresrdcfvg\nuytyrdtesrdfgg\ntdrfygvhct\njh"
+ "gfda\njftyuyiugcf\nhfuygihvftyughbuy\nhgyuftydfhgfyc\ndstryrfdts");
//A long enough String
JScrollBar jb = scrollPane1.getVerticalScrollBar();
jb.setValue(jb.getMinimum());
scrollPane1.repaint();
}
});
btn2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JScrollBar VerticalScrollBar = scrollPane1.getVerticalScrollBar();
VerticalScrollBar.setValue(VerticalScrollBar.getMinimum());
scrollPane1.repaint();
}
});
因此,第一个按钮的功能是:“添加一些文本并滚动到顶部”
但它只会添加文本,而不会滚动到顶部
但是,对于第二个按钮,我添加了一个actionListener,如下所示:
btn1.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
textArea1.setText("jhggjhg\nhugffsrdtfg\ngfdrtdf\nhgftrsdf\nytfresrdcfvg\nuytyrdtesrdfgg\ntdrfygvhct\njh"
+ "gfda\njftyuyiugcf\nhfuygihvftyughbuy\nhgyuftydfhgfyc\ndstryrfdts");
//A long enough String
JScrollBar jb = scrollPane1.getVerticalScrollBar();
jb.setValue(jb.getMinimum());
scrollPane1.repaint();
}
});
btn2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JScrollBar VerticalScrollBar = scrollPane1.getVerticalScrollBar();
VerticalScrollBar.setValue(VerticalScrollBar.getMinimum());
scrollPane1.repaint();
}
});
所以,我在按下第一个按钮后再按下第二个按钮,第二个按钮会很好地执行。
我真的很困惑为什么第一个按钮不会滚动到顶部:一个简单的解决方案可能是使用
JTextArea#setCaretPosition
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JTextArea ta;
public TestPane() {
setLayout(new BorderLayout());
ta = new JTextArea(5, 20);
add(new JScrollPane(ta));
JButton btn = new JButton("Add and to top");
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
ta.setText("jhggjhg\nhugffsrdtfg\ngfdrtdf\nhgftrsdf\nytfresrdcfvg\nuytyrdtesrdfgg\ntdrfygvhct\njh"
+ "gfda\njftyuyiugcf\nhfuygihvftyughbuy\nhgyuftydfhgfyc\ndstryrfdts");
ta.setCaretPosition(0);
}
});
add(btn, BorderLayout.SOUTH);
}
}
}
我曾尝试过使用scrollRectToVisible
,但最终不得不使用SwingUtilites.invokeLater
使其工作,例如
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
ta.scrollRectToVisible(new Rectangle(0, 0, 10, 10));
}
});
所以我想说,
setCaretPosition
在这种情况下是更简单的解决方案例如,一个简单的解决方案可能是使用JTextArea#setCaretPosition
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JTextArea ta;
public TestPane() {
setLayout(new BorderLayout());
ta = new JTextArea(5, 20);
add(new JScrollPane(ta));
JButton btn = new JButton("Add and to top");
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
ta.setText("jhggjhg\nhugffsrdtfg\ngfdrtdf\nhgftrsdf\nytfresrdcfvg\nuytyrdtesrdfgg\ntdrfygvhct\njh"
+ "gfda\njftyuyiugcf\nhfuygihvftyughbuy\nhgyuftydfhgfyc\ndstryrfdts");
ta.setCaretPosition(0);
}
});
add(btn, BorderLayout.SOUTH);
}
}
}
我曾尝试过使用scrollRectToVisible
,但最终不得不使用SwingUtilites.invokeLater
使其工作,例如
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
ta.scrollRectToVisible(new Rectangle(0, 0, 10, 10));
}
});
所以我想说
setCaretPosition
在这种情况下是一个更简单的解决方案你可以使用JTextArea#scrollRectToVisible
,传递它类似于新矩形(0,0,1,1)
是的,他(@MadProgrammer)说的!你可以使用类似于JTextArea#scrollRectToVisible
,传递它类似于新矩形(0,0,1,1)
是的,就像他(@MadProgrammer)说的那样!