Java JScrollPane在空布局中不工作
我是Java Swing新手,尝试在Java代码上使用滚动窗格,但它不起作用。滚动窗格以垂直方向添加到框架上,但未工作。您应该创建自己的面板,扩展包含所有复选框的Java JScrollPane在空布局中不工作,java,swing,layout-manager,null-layout-manager,Java,Swing,Layout Manager,Null Layout Manager,我是Java Swing新手,尝试在Java代码上使用滚动窗格,但它不起作用。滚动窗格以垂直方向添加到框架上,但未工作。您应该创建自己的面板,扩展包含所有复选框的JPanel,并在此面板中覆盖getPreferredSize()方法,如: import javax.swing.JCheckBox; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import ja
JPanel
,并在此面板中覆盖getPreferredSize()
方法,如:
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class ScrollJPanelDemo extends JFrame {
public ScrollJPanelDemo(){
setSize(480, 200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel label = new JLabel("Select one or more options : ");
JCheckBox jcb1 = new JCheckBox("Chandigarh");
JCheckBox jcb2 = new JCheckBox("Mohali");
JCheckBox jcb3 = new JCheckBox("Delhi");
JCheckBox jcb4 = new JCheckBox("Noida");
JCheckBox jcb5 = new JCheckBox("Mumbai");
JCheckBox jcb6 = new JCheckBox("Kolkata");
//creating JPanel to hold the checkboxes
JPanel jpnl = new JPanel();
jpnl.setLayout(null);
jpnl.setOpaque(true);
jcb1.setBounds(0,0,100,40);
jcb2.setBounds(0,60,100,40);
jcb3.setBounds(0,120,100,40);
jcb4.setBounds(0,180,100,40);
jcb5.setBounds(0,240,100,40);
jcb6.setBounds(0,300,100,40);
//adding check boxes and label to the JPanel
jpnl.add(label);
jpnl.add(jcb1);
jpnl.add(jcb2);
jpnl.add(jcb3);
jpnl.add(jcb4);
jpnl.add(jcb5);
jpnl.add(jcb6);
//creating the scroll pane that will scroll the panel.
JScrollPane jscrlPane = new JScrollPane(jpnl);
jscrlPane.setBounds(0,0,300,300);
jscrlPane.setHorizontalScrollBarPolicy
(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS) ;
jscrlPane.setVerticalScrollBarPolicy
(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
//adding that scroll pane to the frame.
getContentPane().add(jscrlPane);
setVisible(true);
}
public static void main(String args[]){
new ScrollJPanelDemo();
}
}
并在代码中使用它:
@Override
public Dimension getPreferredSize()
{
return new Dimension( 300,300 );
}
我看到OP已经为他设置了所需/正确的答案,但该解决方案不适用于动态内容(在我的案例中是垂直于Y轴的),因此我“修复”或更新了Mateusz的原始答案(如果你愿意的话),因此现在它实际上甚至适用于动态JPanel内容(就像在运行中添加其他组件时,我的案例) 这是我的代码(工作,自己使用): 然后,您可以在代码中使用它,实现方式如下:
import java.awt.Component;
import java.awt.Dimension;
import javax.swing.JPanel;
public class JPanelForNullLayoutScroll extends JPanel {
int h;
@Override
public Dimension getPreferredSize() {
if (getComponentCount() > 0) {
h = 0;
for (Component c : getComponents()) {
h += c.getHeight();
}
} else {
h = 0;
}
// as I do not need width recount
//I set it to be taken directly from the component itself
Dimension d = new Dimension(getWidth(), h);
return d;
}
}
。很抱歉,但这个解决方案对我根本不起作用,不幸的是:JScrollPane几乎完全显示了它的滚动条,并且当扩展JPanel的类的内容更改时,滚动条的长度不会更改。我的意思是,它不适用于动态JPanel,这正是我的情况。紧急吗?使用真实的布局可能会节省您的时间和精力。另见。
import java.awt.Component;
import java.awt.Dimension;
import javax.swing.JPanel;
public class JPanelForNullLayoutScroll extends JPanel {
int h;
@Override
public Dimension getPreferredSize() {
if (getComponentCount() > 0) {
h = 0;
for (Component c : getComponents()) {
h += c.getHeight();
}
} else {
h = 0;
}
// as I do not need width recount
//I set it to be taken directly from the component itself
Dimension d = new Dimension(getWidth(), h);
return d;
}
}
int tableW = 300;
int tableH = 300;
// JPANEL WITH NULL LAYOUT
JPanelForNullLayoutScroll container = new JPanelForNullLayoutScroll();
container.setLayout(null);
container.setVisible(true);
container.setEnabled(true);
container.setBounds(0, 0, tableW, tableH);
// SCROLLER
JScrollPane scrollPane = new JScrollPane(container);
scrollPane.setAlignmentX(JLabel.LEFT_ALIGNMENT);
scrollPane.getVerticalScrollBar().setUnitIncrement(8);
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scrollPane.setBounds(0, 0, tableW, tableH);