scrollbardemo.java

180个针对Java初学者的简单实例180个针对Java初学者的简单实例180个针对Java初学者的简单实例

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ScrollBarDemo extends JFrame
                    implements AdjustmentListener{
  //创建水平和重直滚动条                
  JScrollBar vScb = new JScrollBar(JScrollBar.VERTICAL,0,0,0,100);
  JScrollBar hScb = new JScrollBar(JScrollBar.HORIZONTAL,0,0,0,100);
  JPanel panel = new JPanel();
  GridBagLayout Layout=new GridBagLayout();
  GridBagConstraints constraints=new GridBagConstraints();
  JLabel lbVScrollBar =new JLabel("重直滚动条的值",JLabel.CENTER);
  JLabel lbHScrollBar=new JLabel("水平滚动条的值",JLabel.CENTER);
  JTextField tfVScrollBar=new JTextField();
  JTextField tfHScrollBar=new JTextField();
  public ScrollBarDemo() {
    super("滚动条示例");
    setSize(260,200);
    this.getContentPane().setLayout(new BorderLayout());
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
  //以设定的网格包布局向面板中添加组件
  private void addComponent(JPanel panel,GridBagLayout Layout,
                  GridBagConstraints gbc,Component com,int row,int column,
                      int numRows,int numColumns,int Weightx,int Weighty){
   gbc.gridx=row;
   gbc.gridy=column;
   gbc.gridwidth=numRows;
   gbc.gridheight=numColumns;
   gbc.weightx=Weightx;
   gbc.weighty=Weighty;
   Layout.setConstraints(com,gbc);
   panel.add(com);
 }
  public void setLayout(){
    panel.setLayout(Layout);
    constraints.anchor=GridBagConstraints.CENTER;
    constraints.fill=GridBagConstraints.HORIZONTAL;
    //以网格布局向面板添回文本框和标签组件
    addComponent(panel,Layout,constraints,lbHScrollBar,0,0,1,1,20,0);
    addComponent(panel,Layout,constraints,tfHScrollBar,1,0,1,1,80,100);
    addComponent(panel,Layout,constraints,lbVScrollBar,0,1,1,1,20,0);
    addComponent(panel,Layout,constraints,tfVScrollBar,1,1,1,1,80,100);
    //将面板panel、水平和重直滚动条添加到框架中
    this.getContentPane().add(panel, BorderLayout.CENTER);
    this.getContentPane().add(vScb, BorderLayout.EAST);
    this.getContentPane().add(hScb, BorderLayout.SOUTH);
    //注册事件监听器
    vScb.addAdjustmentListener(this);
    hScb.addAdjustmentListener(this);
  }
  public static void main(String[] args) {
    ScrollBarDemo frame = new ScrollBarDemo();
    frame.setLayout();
    frame.show();
  }
  public void adjustmentValueChanged(AdjustmentEvent e) {
     if(e.getSource()==hScb){
       //获取水平滚动条的值，在相应的文本框中显示。
       tfHScrollBar.setText(String.valueOf(hScb.getValue()));
    }
    if(e.getSource()==vScb){
      //显示重直滚动条的当前值
      tfVScrollBar.setText(String.valueOf(vScb.getValue()));
    }
  }
}