jcombobox12006.java

此小程序用于改变输入字符串的大小

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class JComboBox1  implements ItemListener,ActionListener
{
String[] fontsize={"12","14","16","18","20","22","24","26","28"};
String defaultMessage="请选择或直接输入文字大小！";
Font font=null;
JComboBox combo=null;
JLabel label=null;

public JComboBox1()
{
JFrame f=new JFrame("JComboBox");
Container contentPane=f.getContentPane();
contentPane.setLayout(new GridLayout(2,1));
label=new JLabel("Swing",JLabel.CENTER);
font=new Font("SansSerif",Font.PLAIN,12);
label.setFont(font);

combo=new JComboBox(fontsize);
combo.setBorder(BorderFactory.createTitledBorder("请选择你要的文字大小"));
combo.setEditable(true);
ComboBoxEditor editor=combo.getEditor();
combo.configureEditor(editor,defaultMessage);
combo.addItemListener(this);
combo.addActionListener(this);

contentPane.add(label);
contentPane.add(combo);
f.pack();
f.show();
f.addWindowListener(new WindowAdapter(){

public void windowClosing(WindowEvent e){
System.exit(0);
}
});
}

public static void main(String args[])
{
new JComboBox1();
}
public void actionPerformed(ActionEvent e)
{
boolean isaddItem=true;
int fontsize=0;
String tmp=(String)combo.getSelectedItem();
try
{
fontsize=Integer.parseInt(tmp);
for(int i=0;i<combo.getItemCount();i++)
{
if (combo.getItemAt(i).equals(tmp))
{
isaddItem=false;
break;
}
}
if(isaddItem)
{
combo.insertItemAt(tmp,0);
}
font=new Font("SansSerif",Font.PLAIN,fontsize);
label.setFont(font);
}
catch(NumberFormatException ne){
combo.getEditor().setItem("您输入的值不是整数值，请从新输入！");
}
}
public void itemStateChanged(ItemEvent e)
{
if(e.getStateChange()==ItemEvent.SELECTED)
{
int fontsize=0;
try
{fontsize=Integer.parseInt((String)e.getItem());
label.setText("Swing 目前字形大小:"+fontsize);
}
catch(NumberFormatException ne){}
}
}
}