import awb.*;
import java.awt.*;
import java.awt.event.*;

public class DoesItHalt extends java.applet.Applet implements ActionListener
{
    TextField mInstruct;
    IntField gStart;
    Button bStart;
    TextArea mResults;
    int j, k;
    
    
    public void init()
    {   
        mInstruct = new TextField(60);
        mInstruct.setText("Enter starting integer, then push Start.");
        gStart = new IntField(10);
        bStart = new Button("Start");
        mResults = new TextArea(10, 50);
        bStart.addActionListener(this);
        add(mInstruct);
        add(gStart);
        add(bStart);
        add(mResults);
    }           
        
    public void actionPerformed(ActionEvent event)
    {
        Object cause = event.getSource();
        int yea;
        String mak, sty, col, own;
        
        if (cause == bStart)                                                    
        {
            j = 0;
            mResults.setText("Trace of the integer value: \n");
            k = gStart.getInt();
            while (k > 1)
            {                    
                j = j + 1;
                if ((k/2) * 2 == k)     // is k even?
                {
                    k = k / 2;
                }
                else
                {
                    k = 3 * k + 1;
                }
                
            mResults.appendText("k = " + k + "\n");
            }
            mResults.appendText(j + " steps before halting.\n");
        }
    }
}