Java选择菜单的困难，颜色和画线

Question

我正在尝试使用Java Choice Menus创建类似于MS Paint的软件，但是我在使用两个功能方面遇到了一些困难

1. 从“颜色”菜单中选择一种颜色后，出现大量错误文本。我希望实现的是在将PenColour设置为该选项之前，选择颜色将包含该选项的字符串转换为小写字母
2. 尽管相同的代码在未使用Choice的不同applet中起作用，但画线似乎不起作用。我希望它选择两个点，然后在它们之间画一条线。

这是我的代码

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.Choice;

public class PockettProjectTest1 extends Applet implements ActionListener, MouseListener, MouseMotionListener{
//Coordinates and sizes used to draw GUI
    private final int GUI_HEIGHT = 100;
    private final int GUI_START_X = 10;
    private final int GUI_START_Y = 10;
    private final int FIELD_SIZE = 11; //Numbers of characters for text field display
////////////////////////GLOBAL VARIABLES////////////////////////
    private Dimension appletSize; //used to encapsulate the Applets dimensions
    private int x, y, appletHeight, appletWidth, PenThick, PenMode, ShapeMode, ClickXO, ClickYO, ClickXN, ClickYN, ClickCount;
    private String SizeString; 
//a Panel is a container used here to hold and position the GUI components
    private Panel guiPanel;
    private Color PenColour;
//GUI components cv
    public void init(){
        //Disables the applet layout manager and stops automatic GUI component positioning
        setLayout(null);
        setBackground(Color.white);
        addMouseListener(this);  
        addMouseMotionListener(this);  
        addMouseListener(this);  
        ClickCount = 0;
        ClickXO = 0;
        ClickYO = 0;
        ClickXN = 0;
        ClickYN = 0;
        PenMode = 0;
        ShapeMode = 0;
        appletSize = this.getSize(); //captures the Applet dimensions
        appletHeight = appletSize.height; //captures the Applet height
        appletWidth = appletSize.width; //captures the Applet width
        //Set up the Panel ready to hold the GUI components
        guiPanel = new Panel();
        guiPanel.setLocation(0, 0);
        guiPanel.setSize(appletWidth,GUI_HEIGHT);
        guiPanel.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 40));
        guiPanel.setBackground(Color.lightGray);
        add(guiPanel);

        Choice mode = new Choice();
        Choice size = new Choice();
        Choice color = new Choice();
        Choice shape = new Choice();
         
         mode.add("Pen");
         mode.add("Eraser");
         mode.add("Fill");
         mode.add("Shape");
         
         size.add("01px");
         size.add("02px");
         size.add("03px");
         size.add("05px");
         size.add("10px");
         size.add("15px");
         size.add("20px");
         size.add("30px");
         size.add("50px");
         
         
         shape.add("N/A");
         shape.add("Line");
         shape.add("Oval");
         shape.add("Oblong");
         shape.add("Square");
         shape.add("Circle");
         shape.add("FillOval");
         shape.add("FillOblong");
         shape.add("FillSquare");
         shape.add("FillCircle");
         //add choice or combobox
         guiPanel.add(mode);
         guiPanel.add(size);
         guiPanel.add(shape);
         PenThick = 1;
         PenColour = Color.black;
 
    mode.addItemListener(new ItemListener(){
        public void itemStateChanged(ItemEvent ie)
        {
        PenMode = mode.getSelectedIndex();
        
        }
    });
    
     size.addItemListener(new ItemListener(){
        public void itemStateChanged(ItemEvent ie)
        {
        SizeString = size.getSelectedItem();
        PenThick = Integer.parseInt(SizeString.substring(0,2));
        Graphics g = getGraphics();  
        
        }
    });
//// Start of Issue 1:
         colour.addItemListener(new ItemListener(){
        public void itemStateChanged(ItemEvent ie)
        {
        ColourString = colour.getSelectedItem();
        ColourString.toLowerCase();
        Color PenColour.getColor(ColourString);
        }
    });
    /// End of Issue 1
     shape.addItemListener(new ItemListener(){
        public void itemStateChanged(ItemEvent ie)
        {
        ShapeMode = shape.getSelectedIndex();
        }
    });
    
    
}
        
        
    
    public void actionPerformed(ActionEvent e) {
        
    }
    ////Issue 2:
public void mouseReleased(MouseEvent me){  
    if (PenMode == 3) {
    if (ClickCount == 0) {
    ClickXO = me.getX();
    ClickYO = me.getY();
    ClickCount ++;
    System.out.println(ClickCount);
    return;
    }
    if (ClickCount == 1) {
    ClickXN = me.getX();
    ClickYN = me.getY();    
    System.out.println(ClickCount);
    Graphics g = getGraphics();  
    g.setColor(Color.black);
    g.drawLine(ClickXO, ClickYO, ClickXN, ClickYN);
    System.out.println(ClickXO);
    System.out.println(ClickYO);
    System.out.println(ClickXN);
    System.out.println(ClickYN);
    ClickCount = 0; 
    }
    }
        
}
/// End of Issue 2
    public void mousePressed(MouseEvent e){
    }
    
    
    
    public void mouseDragged(MouseEvent e){  
        if (PenMode == 0){
        Graphics g = getGraphics();  
        g.setColor(Color.black);
        g.fillOval(e.getX(), e.getY(), PenThick, PenThick);  
        }
        if (PenMode == 1){
        Graphics g = getGraphics();  
        g.setColor(Color.white);
        g.fillRect(e.getX(), e.getY(), PenThick, PenThick);  
        }
        
}
public void mouseMoved(MouseEvent e){
}  
public void mouseExited(MouseEvent e){
}  
public void mouseEntered(MouseEvent e){
}  
public void mouseClicked(MouseEvent e){
}   
}

我必须在星期五结束前提交这段代码，所以我希望到那时才能解决问题。