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當前程序的目標是在窗口框架中的兩點之間創建厚度不等的線條。到現在爲止還挺好。Java applet如何使用JComboBox中選定的項目
接下來，我想程序識別用戶已經從JComboBox中進行了選擇。
此帖和代碼已更新。 （a）itemStateChanged方法被刪除。它沒有執行，所以不需要在程序中。 （b）每當修改任何對象時，actionPerformed方法都會更新以進行更新。 （c）顏色選擇可能是有史以來最醜陋的開關/案例陳述之一。 （一定會有更好的辦法）。 （d）我實施了Itamar Green的建議，關於JComboBox的定義。謝謝。
我不知道什麼？ 注：Java 8.111。 O/S：Windows 8.1。 IDE：Ecilpse Java EE 4.6.0
所有對改進代碼或問題的迴應都非常感謝。
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class ThickPen extends JApplet implements ActionListener
{
private static final long serialVersionUID = 1L;
JLabel xStartLabel = new JLabel("X Start");
JLabel yStartLabel = new JLabel("Y Start");
JLabel xStopLabel = new JLabel("X Stop");
JLabel yStopLabel = new JLabel("Y Stop");
JLabel thickLabel = new JLabel("Thickness");
JComboBox<String> myColour;
String theColour = "black";
TextField xStartField = new TextField(4);
int xStart = 0;
TextField yStartField = new TextField(4);
int yStart = 0;
TextField xStopField = new TextField(4);
int xStop = 0;
TextField yStopField = new TextField(4);
int yStop = 0;
TextField thicknessField = new TextField(4);
int thick = 0;
String[] colourString = {"black","blue","cyan","darkgray","gray","green",
"lightGray","magenta","orange","pink","red","white","yellow"};
int theIndex = 0;
public void init()
{
setSize(550,500);
Container content = getContentPane();
setLayout(new FlowLayout());
xStartField.addActionListener(this);
yStartField.addActionListener(this);
xStopField.addActionListener(this);
yStopField.addActionListener(this);
thicknessField.addActionListener(this);
add(xStartLabel);
add(xStartField);
add(yStartLabel);
add(yStartField);
add(xStopLabel);
add(xStopField);
add(yStopLabel);
add(yStopField);
add(thickLabel);
add(thicknessField);
myColour = new JComboBox<String>(colourString);
// JComboBox<String> myColour = new JComboBox<String>(colourString);
myColour.setSelectedIndex(0); // start with black
myColour.addActionListener(this);
add(myColour);
content.setBackground(Color.white);
content.setForeground(Color.black);
}
public void paint(Graphics g)
{
super.paint(g);
Dimension d = getSize();
int fullWidth = d.width;
int fullHeight = d.height;
int deltaX = 0;
int deltaY = 0;
boolean xAxis = false;
System.out.println("So far Start x y: "+xStart+" "+yStart+" color: "+theColour);
if (xStart < 1 || xStart > fullWidth
|| yStart < 1 || yStart > fullHeight
|| xStop < 1 || xStop > fullWidth
|| yStop < 1 || yStop > fullHeight
|| thick < 1 || thick > fullHeight || thick > fullWidth) {
String outStr = "Start and stop numbers must be within this window frame";
String outStr2 = "Current width: "+fullWidth+" height: "+fullHeight;
g.setColor(Color.white);
g.fillRoundRect(d.width/4, d.height/4, 300, 40, 4, 4);
g.setColor(Color.red);
g.drawString(outStr, d.width/4+10, d.height/4+15);
g.drawString(outStr2, d.width/4+10, d.height/4+30);
g.drawString("The index: "+theIndex, d.width/4, 300);
} else {
g.drawString("", d.width/4, 260);
deltaX = Math.abs(xStart - xStop); // determine absolute delta of two Xs
deltaY = Math.abs(yStart - yStop); // determine absolute delta of two Ys
if (deltaX > deltaY) // make line thickness based on x axis if
xAxis = false; // the x axis has the most 'room'.
else // else, use the y axis.
xAxis = true;
pickAColour(g, theColour);
drawMyLine(g, xStart, yStart, xStop, yStop, thick, xAxis);
}
g.drawString("The index: "+theIndex, d.width/4, 300);
g.drawString("The color "+ theColour, d.width/4, 330);
}
public void drawMyLine(Graphics g, int xStart, int yStart,
int xStop, int yStop, int thick, boolean xAxis)
{
int count = 0;
while (count < thick)
{
g.drawLine(xStart, yStart, xStop, yStop);
count++;
if (xAxis) {
xStart++;
xStop++;
} else {
yStart++;
yStop++;
}
}
}
public void pickAColour(Graphics g, String theColour)
{
switch (theColour) {
case "black" :
g.setColor(Color.black);
break;
case "blue" :
g.setColor(Color.blue);
break;
case "cyan" :
g.setColor(Color.cyan);
break;
case "darkgray" :
g.setColor(Color.darkGray);
break;
case "gray" :
g.setColor(Color.gray);
break;
case "green" :
g.setColor(Color.green);
break;
case "lightGray" :
g.setColor(Color.lightGray);
break;
case "magenta" :
g.setColor(Color.magenta);
break;
case "orange" :
g.setColor(Color.orange);
break;
case "pink" :
g.setColor(Color.pink);
break;
case "red" :
g.setColor(Color.red);
break;
case "white" :
g.setColor(Color.white);
break;
case "yellow" :
g.setColor(Color.yellow);
break;
} // end of case statement
} // end of pickAColour
public void actionPerformed (ActionEvent ae)
{
Object source=ae.getSource();
// xStart
// if (source==xStartField)
// {
try {
xStart=Integer.parseInt(
xStartField.getText());
}
catch (NumberFormatException x) {
xStart= -1;
}
// }
// yStart
// else if (source==yStartField)
// {
try {
yStart=Integer.parseInt(
yStartField.getText());
}
catch (NumberFormatException x) {
yStart= -1;
}
// }
// xStop
// else if (source==xStopField)
// {
try {
xStop=Integer.parseInt(
xStopField.getText());
}
catch (NumberFormatException x) {
xStop= -1;
}
// }
// yStop
// else if (source==yStopField)
// {
try {
yStop=Integer.parseInt(
yStopField.getText());
}
catch (NumberFormatException x) {
yStop= -1;
}
// }
// thickness
// else if (source==thicknessField)
// {
try {
thick=Integer.parseInt(
thicknessField.getText());
}
catch (NumberFormatException x) {
thick= -1;
}
// } else {
if (source==myColour) {
JComboBox<String> cb = (JComboBox<String>)ae.getSource();
// String theColour = (String)cb.getSelectedItem(); ///can;
// Integer theIndex = (int)cb.getSelectedIndex();
theColour = (String)cb.getSelectedItem();
theIndex = (int)cb.getSelectedIndex();
}
// }
repaint();
} // end of ActionEvent
} // end of class
你解決了這個問題嗎？ – ItamarG3
感謝您的回覆。我更接近解決方案。你所描述的改變並不能解決問題。我離得更近，因爲程序不會崩潰。 （a）刪除對itemStateChanged的所有引用。該方法沒有執行，因此被刪除。 （b）我大大改變了行動的執行。我將嘗試編輯帖子以反映更改.... – johniccp