Java 为什么在绘制图像后,jcombobox仅在选择其项目2次后才响应?
这是一个程序,它获取一个链接并在画布上绘制它……但是当它停止工作时,窗口右侧的jcombobox必须选择它2次才能更改为所选的数字。此外,我还看到绘制和重新绘制方法非常不稳定,有时图像不会出现,或者如果出现,当你最大化窗口时,图像会再次消失Java 为什么在绘制图像后,jcombobox仅在选择其项目2次后才响应?,java,swing,awt,paint,jcombobox,Java,Swing,Awt,Paint,Jcombobox,这是一个程序,它获取一个链接并在画布上绘制它……但是当它停止工作时,窗口右侧的jcombobox必须选择它2次才能更改为所选的数字。此外,我还看到绘制和重新绘制方法非常不稳定,有时图像不会出现,或者如果出现,当你最大化窗口时,图像会再次消失 package bigProgram; import java.awt.BorderLayout; import java.awt.Color; import java.awt.Component; import java.awt.Containe
package bigProgram;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.LayoutManager;
import java.awt.Rectangle;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ContainerListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.Raster;
import java.awt.image.RenderedImage;
import java.awt.image.SampleModel;
import java.awt.image.WritableRaster;
import java.io.IOException;
import java.net.URL;
import java.util.Vector;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import java.awt.*;
public class First extends JFrame implements ActionListener,ItemListener
{
JButton test;
JTextField fill,fillout;
String web=null;
BufferedImage im;
JPanel cuadro=new JPanel();
Image out;
Container cont;
JComboBox<Integer> scale;
double mini;
int x,y;
int sh,sw;
String seleccionado;
Canvas space;
public First()
{
//ventana
setTitle("Image Scalerprinter");
setBounds(200,200,700,670);
setResizable(true);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
BorderLayout fer=new BorderLayout();
setLayout(fer);
//espacio para dibujar
space=new Canvas();
space.setVisible(false);
add(space,fer.CENTER);
//boton
test=new JButton("Test");
test.setPreferredSize(new Dimension(60, 40));
add(test,fer.WEST,0);
test.setActionCommand("T");
test.addActionListener(this);
//texto IN
fill=new JTextField();
fill.setPreferredSize(new Dimension(200,20));
add(fill,fer.NORTH,1);
//texto OUT
fillout=new JTextField();
fillout.setPreferredSize(new Dimension(200,20));
add(fillout,fer.SOUTH,2);
//opcion para escalarlo
scale=new JComboBox<Integer>();
scale.setPreferredSize(new Dimension(50,40));
for(int i=100;i>0;i--)
{
scale.addItem(i);
}
add(scale,fer.EAST);
scale.addItemListener(this);
setVisible(true);
}
///accion para cerrar
private void setDefaultCloseOperation(Object exit)
{
}
//metodo para borrar
public void clearRect()
{
repaint();
}
//accion del boton
@Override
public void actionPerformed(ActionEvent e)
{
if(e.getActionCommand().equals("T"))
{
if(fill.getText()!=null)
{
web=fill.getText();
try
{
URL r=new URL(web);
im =ImageIO.read(r);
System.out.println("yes");
out= im.getScaledInstance(500, 500, Image.SCALE_SMOOTH);
space.repaint();
}
catch (IOException e1)
{
e1.printStackTrace();
}
}
}
}
//aacion para el scale
public void itemStateChanged(ItemEvent e) {
if (e.getSource()==scale)
{
mini=(int) e.getItem();//esta funcionando!
double size=mini/100;
scale.setName(getName());
double sh= out.getHeight(null)*size;
sw=(int) (out.getWidth(null)*size);
System.out.println("real size:"+out.getHeight(null)+" height\n "+
out.getWidth(null)+" width "+"new: "+sh+" and "+sw);
out.getScaledInstance(sw, (int) sh,Image.SCALE_FAST);
repaint();
setVisible(true);
}
}
//metodo para pintar cosas
public void paint (Graphics g)
{
x=100;
y=100;
g.drawImage(out, x,y,null);
}
public static void main(String[] args)
{
First one=new First();
//"http://www.downtoearthservices.co.uk/resources/tree2.gif" this is the link to paste in the jtextfield
}
package程序;
导入java.awt.BorderLayout;
导入java.awt.Color;
导入java.awt.Component;
导入java.awt.Container;
导入java.awt.Dimension;
导入java.awt.FlowLayout;
导入java.awt.Graphics;
导入java.awt.Image;
导入java.awt.LayoutManager;
导入java.awt.Rectangle;
导入java.awt.Window;
导入java.awt.event.ActionEvent;
导入java.awt.event.ActionListener;
导入java.awt.event.ContainerListener;
导入java.awt.event.ItemEvent;
导入java.awt.event.ItemListener;
导入java.awt.event.KeyListener;
导入java.awt.image.buffereImage;
导入java.awt.image.ColorModel;
导入java.awt.image.graster;
导入java.awt.image.renderImage;
导入java.awt.image.SampleModel;
导入java.awt.image.WritableRaster;
导入java.io.IOException;
导入java.net.URL;
导入java.util.Vector;
导入javax.imageio.imageio;
导入javax.swing.JButton;
导入javax.swing.JComboBox;
导入javax.swing.JComponent;
导入javax.swing.JFrame;
导入javax.swing.JPanel;
导入javax.swing.JTextField;
导入java.awt.*;
公共类首先扩展JFrame实现ActionListener、ItemListener
{
JButton试验;
JTextField填充,fillout;
字符串web=null;
缓冲图像im;
JPanel cuadro=新的JPanel();
图像输出;
集装箱运输;
JComboBox量表;
双迷你;
int x,y;
内西,西南;;
字符串选择;
画布空间;
公共优先
{
//文塔纳
setTitle(“图像缩放打印机”);
挫折(200700670);
可设置大小(真);
此.setDefaultCloseOperation(关闭时退出);
BorderLayout fer=新的BorderLayout();
设置布局(fer);
//埃斯帕西奥帕拉迪布贾尔酒店
空格=新画布();
space.setVisible(false);
添加(空间,相对中心);
//波顿
测试=新按钮(“测试”);
测试。设置首选尺寸(新尺寸(60,40));
添加(测试,西弗,0);
test.setActionCommand(“T”);
test.addActionListener(this);
//文本输入
fill=新的JTextField();
填充。设置首选尺寸(新尺寸(200,20));
添加(填充,北向,1);
//发短信
fillout=新的JTextField();
fillout.setPreferredSize(新尺寸(200,20));
增加(填写,南部,2);
//埃斯卡拉罗医院
scale=新的JComboBox();
比例。设置首选尺寸(新尺寸(50,40));
对于(int i=100;i>0;i--)
{
比例尺.增补项(i);
}
添加(比例,参考东部);
scale.addItemListener(此);
setVisible(真);
}
///塞拉公寓
私有void setDefaultCloseOperation(对象退出)
{
}
//梅托帕拉博拉尔酒店
public void clearRect()
{
重新油漆();
}
//波顿公寓
@凌驾
已执行的公共无效操作(操作事件e)
{
如果(例如getActionCommand().equals(“T”))
{
if(fill.getText()!=null)
{
web=fill.getText();
尝试
{
URL r=新的URL(web);
im=图像读取(r);
System.out.println(“是”);
out=im.getScaledInstance(500500,Image.SCALE\u平滑);
space.repaint();
}
捕获(IOE1异常)
{
e1.printStackTrace();
}
}
}
}
//阿西翁帕拉埃尔量表
公共无效itemStateChanged(ItemEvent e){
如果(例如getSource()==比例)
{
mini=(int)e.getItem();//esta functionAndo!
双倍尺寸=迷你/100;
scale.setName(getName());
double sh=out.getHeight(null)*大小;
sw=(int)(out.getWidth(null)*大小);
System.out.println(“实际大小:“+out.getHeight(null)+”height\n”+
out.getWidth(null)+“width”+“new:“+sh+”和“+sw”);
out.getScaledInstance(sw,(int)sh,Image.SCALE\u FAST);
重新油漆();
setVisible(真);
}
}
//美托多帕拉品塔尔美容院
公共空间涂料(图g)
{
x=100;
y=100;
g、 drawImage(输出、x、y、空);
}
公共静态void main(字符串[]args)
{
第一个=新的第一个();
//"http://www.downtoearthservices.co.uk/resources/tree2.gif“这是要粘贴到jtextfield中的链接
}
super.paint(g)
,将导致绘制工件,这将破坏绘制链JFrame
)上进行绘制,因为它们不是双缓冲的,并且它们已经在组件中承载了绘制的负载。相反,在JPanel
或JComponent
上进行绘制,并重写paintComponent
并调用super.paintComponent()
JPanel
上绘制时,您应该覆盖getPreferredSize()
并只pack()
框架容器
@Override
public Dimension getPreferredSize() {
return new Dimension(700, 670);
}
super.paint(g)
,将导致绘制工件,这将破坏绘制链JFrame
这样的顶级容器上进行绘制,因为它们不是双缓冲的,而且
@Override
public Dimension getPreferredSize() {
return new Dimension(700, 670);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
public void run() {
First one = new First();
JFrame frame = new JFrame("Frame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(one);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
mini = (int) e.getItem();//esta funcionando!
inconvertible types: required: int found: java.lang.Object
mini = (Integer)(e.getItem());//esta funcionando!