【计算机类职业资格】(A)二级JAVA笔试-4及答案解析.doc

1、A)二级 JAVA 笔试-4 及答案解析(总分：100.00，做题时间：90 分钟)一、基本操作题(总题数：1，分数：30.00)1.本题中定义了长度为 20 的一维整型数组 a，并将数组元素的下标值赋给数组元素，最后打印输出数组中下标为奇数的元素。public class java1public static void main(String args)int a=_;int i;for(_; i+)ai=i;for(i=0; i20; i+)if(_)System. out. print(“a“+i+“=“+ai+“,“);（分数：30.00）填空项 1:_二、简单应用题(总题数：1，分

2、数：30.00)2.本题中定义了一个树型的通信录，窗口左侧是一个树，右侧是一个文本域，单击树的结点，则在右侧文本域中显示相关信息，如果单击的是树结点，则显示对应名字的电话信息。import javax. swing. * ;import javax. swing. tree. * ;import java. awt. * ;import java. awt. event. * ;import javax. swing. event. * ;class Mytree2 extends JFrame_JTree tree=null; JTextArea text=new JTextArea(20,

3、20);Mytree2()Container con=getContentPane();DefauhMutableTreeNode root=new DefauhMutableTreeNode (“同学通信录“);DefaultMutableTreeNode t1=new DefauhMutableTreeNode(“大学同学“);DefaultMutableTreeNode t2=new DefaultMutableTreeNode(“研究生同学“);DefaultMutableTreeNode t1_1=new DefauhMutableTreeNode(“陈艳“);DefauhMutab

4、leTreeNode t1_2=new DefaultMutableTreeNode(“李小永“);DefauhMutableTreeNode t2_1=new DefaultMutableTreeNode(“王小小“);DefaultMutableTreeNode t2_2=new DefaultMutableTreeNode(“董小“);setTitle(“java2“);root. add(t1); root. add(t2);t1. add(t1_1); t1, add(t1_2); t2. add(t2_1); t2. add(t2_2);tree=new JTree(root);J

5、ScrollPane scrollpane=new JScrollPane(text);JSplitPane splitpane=new JSplitPane(JSplitPane. HORIZONTAL_SPLIT,true, tree, scrollpane);tree. addTreeSelectionListener(this);con. add(splitpane);addWindowListener( new WindowAdapter()public void windowClosing(WindowEvent e)System. exit(0););setVisible(tru

6、e); setBounds(70,80,200,300);public void valueChanged(TreeSelectionEvent e)if(e, getSource()=tree)DefaultMutableTreeNode node=(DefaultMutableTreeNode) tree. getLastSelectedPathComponent();if(node. isLeaf()String str=_;if(str. equals(“陈艳“)text. setText(str+“:联系电话: 0411-4209876“);else if(str. equals(“

7、李小永“)text. setText (str+“:联系电话: 010 -62789876“);else if(str. equals(“王小小“)text. setText (str+“: 联系电话: 0430-63596677“);else if(str. equals(“董小“)text. setText(str +“: 联系电话: 020-85192789“);elsetext. setText(node. getUserObject(). toString();public class java2public static void main(String args)Mytree2

8、win=new Mytree2(); win. pack();（分数：30.00）填空项 1:_三、综合应用题(总题数：1，分数：40.00)3.本题中，鼠标在窗口中单击一下，就在单击的位置生成一个小矩形，如果在小矩形上双击鼠标左键，则删除小矩形。import java. awt. * ;import java. awt. event. * ;import javax. swing. * ;class MousePanel extends JPanel extends MouseMotionListenerpublic MousePanel()addMouseListener(new Mous

9、eAdapter()public void mousePressed(MouseEvent evt)int x=evt. getX();int y=evt. getY();current=find(x, y);if(current0)add(x, y);public void mouseClicked(MouseEvent evt)int x=evt. getX();int y=evt. getY();if(evt. getClickCount()=2)remove(current););addMouseMotionListener(this);public void paintCompone

10、nt(Graphics g)(super. paintComponent();for (int i=0; insquares; i+)draw(g, i);public int find(int x, int y)for(int i=0; insquares; i+)if (squaresi. x-SQUARELENGTH/2=xreturn-1;public void draw(Graphics g, int i)g. drawRect(squaresi. x-SQUARELENGTH/2,squaresi. y-SQUARELENGTH/2,SQUARELENGTH,SQUARELENGT

11、H);public void add(int x, int y)if(nsquaresMAXNSQUARES)squaresnsquares=new Point(x, y);current=nsquares;nsquares+;repaint();public void remove(int n)if(n0|n=nsquares) return;nsquares-;squaresn=squaresnsquares;if(current=n) current=-1;repaint();public void mouseMoved(MouseEvent evt)public void mouseD

12、ragged(MouseEvent evt)private static final int SQUARELENGTH=10;private static final int MAXNSQUARES=100;private Point squares=new Point MAXNSQUARES;private int nsquares=0;private int current=-1;class MouseFrame extends JFramepublic MouseFrame()setTitle(“java3“);setSize(300,200);addWindowListener(new

13、 WindowAdapter()public void windowClosing(WindowEvent e)System. exit(0););Container contentPane=getContentPane();contentPane. add (MousePanel();public class java3public static void main(String args)JFrame frame=new MouseFrame();frame. show();（分数：40.00）填空项 1:_(A)二级 JAVA 笔试-4 答案解析(总分：100.00，做题时间：90 分钟

14、)一、基本操作题(总题数：1，分数：30.00)1.本题中定义了长度为 20 的一维整型数组 a，并将数组元素的下标值赋给数组元素，最后打印输出数组中下标为奇数的元素。public class java1public static void main(String args)int a=_;int i;for(_; i+)ai=i;for(i=0; i20; i+)if(_)System. out. print(“a“+i+“=“+ai+“,“);（分数：30.00）填空项 1:_ （正确答案：第 1 处：new int20第 2 处：i=0; i20第 3 处：i%2!=0）解析：解析 第

15、1 处定义了长度为 20 的一维整型数组 a；第 2 处的 for 循环将数组元素的下标值赋给数组元素；第 3 处判断数组各个元素下标是否为奇数。二、简单应用题(总题数：1，分数：30.00)2.本题中定义了一个树型的通信录，窗口左侧是一个树，右侧是一个文本域，单击树的结点，则在右侧文本域中显示相关信息，如果单击的是树结点，则显示对应名字的电话信息。import javax. swing. * ;import javax. swing. tree. * ;import java. awt. * ;import java. awt. event. * ;import javax. swing.

16、event. * ;class Mytree2 extends JFrame_JTree tree=null; JTextArea text=new JTextArea(20,20);Mytree2()Container con=getContentPane();DefauhMutableTreeNode root=new DefauhMutableTreeNode (“同学通信录“);DefaultMutableTreeNode t1=new DefauhMutableTreeNode(“大学同学“);DefaultMutableTreeNode t2=new DefaultMutableT

17、reeNode(“研究生同学“);DefaultMutableTreeNode t1_1=new DefauhMutableTreeNode(“陈艳“);DefauhMutableTreeNode t1_2=new DefaultMutableTreeNode(“李小永“);DefauhMutableTreeNode t2_1=new DefaultMutableTreeNode(“王小小“);DefaultMutableTreeNode t2_2=new DefaultMutableTreeNode(“董小“);setTitle(“java2“);root. add(t1); root. a

18、dd(t2);t1. add(t1_1); t1, add(t1_2); t2. add(t2_1); t2. add(t2_2);tree=new JTree(root);JScrollPane scrollpane=new JScrollPane(text);JSplitPane splitpane=new JSplitPane(JSplitPane. HORIZONTAL_SPLIT,true, tree, scrollpane);tree. addTreeSelectionListener(this);con. add(splitpane);addWindowListener( new

19、 WindowAdapter()public void windowClosing(WindowEvent e)System. exit(0););setVisible(true); setBounds(70,80,200,300);public void valueChanged(TreeSelectionEvent e)if(e, getSource()=tree)DefaultMutableTreeNode node=(DefaultMutableTreeNode) tree. getLastSelectedPathComponent();if(node. isLeaf()String

20、str=_;if(str. equals(“陈艳“)text. setText(str+“:联系电话: 0411-4209876“);else if(str. equals(“李小永“)text. setText (str+“:联系电话: 010 -62789876“);else if(str. equals(“王小小“)text. setText (str+“: 联系电话: 0430-63596677“);else if(str. equals(“董小“)text. setText(str +“: 联系电话: 020-85192789“);elsetext. setText(node. ge

21、tUserObject(). toString();public class java2public static void main(String args)Mytree2 win=new Mytree2(); win. pack();（分数：30.00）填空项 1:_ （正确答案：第 1 处：implements TreeSelectionListener第 2 处：node. toString()）解析：解析 第 1 处实现了一个 JTree 的监听器接口；第 2 处将 node 转换成 String 型。三、综合应用题(总题数：1，分数：40.00)3.本题中，鼠标在窗口中单击一下，就

22、在单击的位置生成一个小矩形，如果在小矩形上双击鼠标左键，则删除小矩形。import java. awt. * ;import java. awt. event. * ;import javax. swing. * ;class MousePanel extends JPanel extends MouseMotionListenerpublic MousePanel()addMouseListener(new MouseAdapter()public void mousePressed(MouseEvent evt)int x=evt. getX();int y=evt. getY();cur

23、rent=find(x, y);if(current0)add(x, y);public void mouseClicked(MouseEvent evt)int x=evt. getX();int y=evt. getY();if(evt. getClickCount()=2)remove(current););addMouseMotionListener(this);public void paintComponent(Graphics g)(super. paintComponent();for (int i=0; insquares; i+)draw(g, i);public int

24、find(int x, int y)for(int i=0; insquares; i+)if (squaresi. x-SQUARELENGTH/2=xreturn-1;public void draw(Graphics g, int i)g. drawRect(squaresi. x-SQUARELENGTH/2,squaresi. y-SQUARELENGTH/2,SQUARELENGTH,SQUARELENGTH);public void add(int x, int y)if(nsquaresMAXNSQUARES)squaresnsquares=new Point(x, y);cu

25、rrent=nsquares;nsquares+;repaint();public void remove(int n)if(n0|n=nsquares) return;nsquares-;squaresn=squaresnsquares;if(current=n) current=-1;repaint();public void mouseMoved(MouseEvent evt)public void mouseDragged(MouseEvent evt)private static final int SQUARELENGTH=10;private static final int M

26、AXNSQUARES=100;private Point squares=new Point MAXNSQUARES;private int nsquares=0;private int current=-1;class MouseFrame extends JFramepublic MouseFrame()setTitle(“java3“);setSize(300,200);addWindowListener(new WindowAdapter()public void windowClosing(WindowEvent e)System. exit(0););Container conte

27、ntPane=getContentPane();contentPane. add (MousePanel();public class java3public static void main(String args)JFrame frame=new MouseFrame();frame. show();（分数：40.00）填空项 1:_ （正确答案：第 1 处：extends JPanel implements MouseMotionListener第 2 处：super. paintComponent(g)第 3 处：eontentPane. add(new MousePanel()）解析：解析 第 1 处是继承 Jpanel 实现鼠标移动监听器接口；第 2 处以 g 为参数重新绘制组件；第 3 处在 contentPane 内容面板中添加一个 MousePanel 鼠标面板。