1、二级 JAVA 机试-38 及答案解析(总分：100.00，做题时间：90 分钟)一、1基本操作题(总题数：1，分数：33.00)1.private static int size；（分数：33.00）_二、2简单应用题(总题数：1，分数：33.00)2.请完成下列 Java 程序：创建一个进度条，可以控制其开始和暂停。要求进度条与线程关联，由线程控制，点击开始按钮开始进度条的滚动，点击停止按钮，暂停，继续点击开始按钮则继续进行。注意：请勿改动 main()主方法和其他已有的语句内容，仅在横线处填入适当的语句。import javax.swing.*；import javax.swing.ev
2、ent.*；import java.awt.*；import java.awt.event.*；public class ex15_2 extends JPanel ThreadProg thProgress；JProgressBar jPb；/声明一个进程条对象static JFrame jf；public ex15_2()setLayout(new BorderLayout()；jPb=new JProgressBar()；add(jpb,“Center“)；JPanel btnPanel=new JPanel()；JButton btnStart=new JButton(“开始“)；bt
3、nPanel.add(btnStart)；btnStart.addActionListener(new ActionListener()public void actionPerformed(ActionEvent ae)_；)；JButton btnStop=new JButton(“停止“)；btnPanel.add(btnStop)；btnStop.addActionListener(new ActionListener()public void actionPerformed(ActionEvent ae)_；)；add(btnPanel，BorderLayout.SOUTH)；pub
4、lic void startProgress()if(thProgress=null|!thProgress.isAlive()thProgress=new ThreadProg(jpb)；thProgress.start()；public void stopProgress()thProgress.setStop(true)；public static VOid main(String args)jf=new JPrame(“ex15_2“)；ex15_2 obj15_2=new ex15_2()；jf.getContentPane().add(“Center“,obj15_2)；jf.se
5、tSize(250，80)；jf.addWindowListener(new WindowAdapter()pubhc void windowClosing(WindowEvent we)System.exit(0)；)；jf.setVisible(true)；class ThreadProg extends Threadprivate JProgressBar jpb；private boolean bStop=false；private boolean bAlive=false；pubhc ThreadProg(JProgressBar jpb)this.jpb=jpb；public VO
6、id setStop(boolean b)bStop=b；public void run()int min=0；int max=60；jpb.setMinimum(min)；jpb.setMaximum(max)；jpb.setValue(min)；for(int x=min;x=max;x+)if(bStop)break；elsejpb.setValue(x)；tryThread.sleep(150)；catch(InterruptedException e)bAlive=false；（分数：33.00）_三、3综合应用题(总题数：1，分数：34.00)3.下面是一个 Applet 程序，其
7、功能是在窗口中绘制 3 个半径递增的圆，并用 RGB 三原色对这 3 个圆填充。要求建立一个绘制圆的类，实现根据指定颜色进行填充的功能，在主程序中通过调用这个类的方法实现圆的绘制。请改正程序中的错误(有下画线的语句)，使程序能输出正确的结果。注意：不改动程序的结构，不得增行或删行。import java.applet.*；import java.awt.*；import java.awt.*；/*applet code=“ex15_3.class“width=800 height=400/applet*/class CanvasCircle extends Canvasprivate Colo
8、r cCircle；public CanvasCircle(Color c)cCircle=c；public void paint(Graphics g)int dimCircle，xCircle，yCircle；Dimension sizeCurrent=getSize()；if(sizeCurrent.widthsizeCurrent.height)dimCircle=sizeCurrent.width；elsedimCircle=sizeCurrent.height；g.setColor(cCircle)；xCircle=(sizeCurrent.heighe-dimCircle)/2；
9、yCircle=(sizeCurrent.width-dimCircle)/2；g.fillOval(xCircle,yCircle,dimCircle,dimCircle)；public class exl5_3 extends Appletpublic void init()GridBagLayout gbl=new GddBagLayout()；GridBagConstraints gbc=new CridBagConstraints()；CanvasCircle circleNew；setLayout(gbl)；gbc.weightx=1.0；gbc.weighty=1.0；gbc.f
10、ill=GridBagConstraints.BOTH；circleNew=new CanvasCircle(Color.red)；gbl.setConstraints(circleNew，gbc)；add(circleNeW)；gbc.weightx=1.5；gbc.weighty=1.5；circleNew=new CanvasCircle(Color.green)；gbl.sctConstraints(eircleNew，gbc)；add(circleNew)；gbc.weightx=2.0；gbc.weighty=2.0；circleNew=new CanvasCircle(Color
11、.blue)；gbl.setConstraints(circleNew,gbc)；add(circleNew)；ex15_3.htmlHTMLHEADTITLEex15_3/TITLE/HEADBODYapplet code=“ex15_3.class“width=800 height=400/applet/BODY/HTMI（分数：34.00）_二级 JAVA 机试-38 答案解析(总分：100.00，做题时间：90 分钟)一、1基本操作题(总题数：1，分数：33.00)1.private static int size；（分数：33.00）_正确答案：(size+；Outer.this.s
12、ize+；Inner k=new lnner()；)解析：二、2简单应用题(总题数：1，分数：33.00)2.请完成下列 Java 程序：创建一个进度条，可以控制其开始和暂停。要求进度条与线程关联，由线程控制，点击开始按钮开始进度条的滚动，点击停止按钮，暂停，继续点击开始按钮则继续进行。注意：请勿改动 main()主方法和其他已有的语句内容，仅在横线处填入适当的语句。import javax.swing.*；import javax.swing.event.*；import java.awt.*；import java.awt.event.*；public class ex15_2 exten
13、ds JPanel ThreadProg thProgress；JProgressBar jPb；/声明一个进程条对象static JFrame jf；public ex15_2()setLayout(new BorderLayout()；jPb=new JProgressBar()；add(jpb,“Center“)；JPanel btnPanel=new JPanel()；JButton btnStart=new JButton(“开始“)；btnPanel.add(btnStart)；btnStart.addActionListener(new ActionListener()publi
14、c void actionPerformed(ActionEvent ae)_；)；JButton btnStop=new JButton(“停止“)；btnPanel.add(btnStop)；btnStop.addActionListener(new ActionListener()public void actionPerformed(ActionEvent ae)_；)；add(btnPanel，BorderLayout.SOUTH)；public void startProgress()if(thProgress=null|!thProgress.isAlive()thProgres
15、s=new ThreadProg(jpb)；thProgress.start()；public void stopProgress()thProgress.setStop(true)；public static VOid main(String args)jf=new JPrame(“ex15_2“)；ex15_2 obj15_2=new ex15_2()；jf.getContentPane().add(“Center“,obj15_2)；jf.setSize(250，80)；jf.addWindowListener(new WindowAdapter()pubhc void windowCl
16、osing(WindowEvent we)System.exit(0)；)；jf.setVisible(true)；class ThreadProg extends Threadprivate JProgressBar jpb；private boolean bStop=false；private boolean bAlive=false；pubhc ThreadProg(JProgressBar jpb)this.jpb=jpb；public VOid setStop(boolean b)bStop=b；public void run()int min=0；int max=60；jpb.se
17、tMinimum(min)；jpb.setMaximum(max)；jpb.setValue(min)；for(int x=min;x=max;x+)if(bStop)break；elsejpb.setValue(x)；tryThread.sleep(150)；catch(InterruptedException e)bAlive=false；（分数：33.00）_正确答案：(startProgress()stopProgress()解析：三、3综合应用题(总题数：1，分数：34.00)3.下面是一个 Applet 程序，其功能是在窗口中绘制 3 个半径递增的圆，并用 RGB 三原色对这 3
18、个圆填充。要求建立一个绘制圆的类，实现根据指定颜色进行填充的功能，在主程序中通过调用这个类的方法实现圆的绘制。请改正程序中的错误(有下画线的语句)，使程序能输出正确的结果。注意：不改动程序的结构，不得增行或删行。import java.applet.*；import java.awt.*；import java.awt.*；/*applet code=“ex15_3.class“width=800 height=400/applet*/class CanvasCircle extends Canvasprivate Color cCircle；public CanvasCircle(Color
19、 c)cCircle=c；public void paint(Graphics g)int dimCircle，xCircle，yCircle；Dimension sizeCurrent=getSize()；if(sizeCurrent.widthsizeCurrent.height)dimCircle=sizeCurrent.width；elsedimCircle=sizeCurrent.height；g.setColor(cCircle)；xCircle=(sizeCurrent.heighe-dimCircle)/2；yCircle=(sizeCurrent.width-dimCircl
20、e)/2；g.fillOval(xCircle,yCircle,dimCircle,dimCircle)；public class exl5_3 extends Appletpublic void init()GridBagLayout gbl=new GddBagLayout()；GridBagConstraints gbc=new CridBagConstraints()；CanvasCircle circleNew；setLayout(gbl)；gbc.weightx=1.0；gbc.weighty=1.0；gbc.fill=GridBagConstraints.BOTH；circleN
21、ew=new CanvasCircle(Color.red)；gbl.setConstraints(circleNew，gbc)；add(circleNeW)；gbc.weightx=1.5；gbc.weighty=1.5；circleNew=new CanvasCircle(Color.green)；gbl.sctConstraints(eircleNew，gbc)；add(circleNew)；gbc.weightx=2.0；gbc.weighty=2.0；circleNew=new CanvasCircle(Color.blue)；gbl.setConstraints(circleNew,gbc)；add(circleNew)；ex15_3.htmlHTMLHEADTITLEex15_3/TITLE/HEADBODYapplet code=“ex15_3.class“width=800 height=400/applet/BODY/HTMI（分数：34.00）_正确答案：(sizeCurrent.widthsizeCurrent.heightxCircle=(sizeCurrent.width-dimCircle)/2yCircle=(sizeCurrent.height-dimCircle)/2)解析：
