1、计算机二级 JAVA-138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：30.00)1.本题程序的功能是计算 110(包括 1和 10)中除 5以外各个自然数的和。请将下述程序补充完整(注意：不得改动程序的结构，不得增行或删行)。 public class basic public static void main (String args) int i = 1; int sum = 0; while(i = 10) if(i = 5) _; _; _; i+; System.out.println (“sum=“+sum); （分数：30.00）
2、_二、2简单应用题(总题数：1，分数：40.00)2.本题程序的功能是定义一个简单的计算器，可以进行基本的四则运算。程序中布局了 16个按钮用来表示数字 09 及运算符和点号，程序顶部的文本框用来显示运算数及结果。请将下述程序补充完整(注意：不得改动程序的结构，不得增行或删行)。 import java.awt.*; import java.awt.event.*; import javax.swing.*; public class simple public static void main (String args) try UIManager.setLookAndFeel(UIMana
3、ger.getSystemLookAndFeelClassName(); catch (Exception e) JFrame frame = new CalculatorFrame(); frame.show(); class CalculatorPanel extends JPanel implements ActionListener private JTextField display; private JButton btn; private double arg = 0; private String op = “=“; private boolean start = true;
4、public CalculatorPanel() setLayout(new BorderLayout(); display = new JTextField(“0“); display.setEditable(false); add(display,“North“); JPanel p = new JPanel(); p.setLayout(new GridLayout(4,4); String buttons = “789/456“123-0.= +“; for (int i = 0; i buttons.length(); i +) btn = new JButton(buttons.s
5、ubstring(i,i + 1); p.add(btn); _; add(p,“Center“); public void actionPerformed(ActionEvent evt) String s = evt.getActionCommand(); if (“0“ = s.charAt(0)s.charAt(0) =“9“ |s.equals(“.“) if (start) display.setText(s); else display.setText(display.getText() + s); start = false; else if (start) if (s.equ
6、als(“-“) display.setText(s); start = false; else op = s; else double x =_; calculate(x); op = s; start = true; public void calculate(double n) if (op.equals(“ + “) arg += n; else if(op.equals(“-“) arg - = n; else if(op.equals(“*“) arg *= n; else if(op.equals(“/“) arg /= n; else if(op.equals(“=“) arg
7、=n; display.setText(“+ arg); class CalculatorFrame extends Jframe public CalculatorFrame() setTitle(“simple“); setSize(220,180); addWindowListener(new WindowAdapter() public void windowClosing(WindowEvent e) System.exit(0); ); Container contentPane=getContentPane(); contentPane.add(new CalculatorPan
8、el(); （分数：40.00）_三、3综合应用题(总题数：1，分数：30.00)3.本题程序的功能是用键盘上的方向键来控制直线的绘制方向。如果一直按向上的方向键，则在窗口中从焦点开始向上缓慢绘制直线，按其他方向的方向键也会向对应的方向缓慢地绘制直线。如果按下 Shift键，绘制直线的速度会加快。请将下述程序补充完整(注意：不得改动程序的结构，不得增行或删行)。 import java.awt.*; import java.awt.geom.*; import java.util.*; import java.awt.event.*; import javax.swing.*; public
9、class advance public static void main(String args) SketchFrame frame = new SketchFrame(); frame.setDefaultCloseOperation(JFrame.EXIT ON CLOSE); frame,show (); class SketchFrame extends JFrame public SketchFrame() setTitle(“advance“); setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT); SketchPanel panel = new Ske
10、tchPanel(); Container contentPane = getContentPane(); contentPane.add(panel); public static final int DEFAULT_WIDTH = 300; public static final int DEFAULT_HEIGHT = 200; class SketchPanel extends JPanel _; last = new Point2D.Double(100,100); lines = new ArrayList(); KeyHandler listener = new KeyHandl
11、er(); _; setFocusable(true); public void add(int dx,int dy) Point2D end = new Point2D.Double(last.getX()+ dx,last.getY() + dy); Line2D line = new Line2D.Double(last,end); lines.add(line); repaint(); last = end; public void paintComponent(Graphics g) super.paintComponent(g); Graphics2D g2 = (Graphics
12、2D)g; for (int i = 0; i lines.size(); i+) g2 .draw (Line2D) lines .get (i); private Point2D last; private ArrayList lines; private static final int SMALL INCREMENT = i; private static final int LARGE_INCREMENT = 5; private class KeyHandler implements KeyListener public void keyPressed(KeyEvent event
13、) _; int d; if (event.isShiftDown() d = LARGE_INCREMENT; else d = SMALL_INCREMENT; if(keyCode = KeyEvent.VK_LEFT) add(-d,0); else if(keyCode = KeyEvent.VK_RIGHT) add(d,0); else if(keyCode = KeyEvent.VK_UP) add(0,-d); else if(keyCode = KeyEvent.VK DOWN) add(0,d); public void keyReleased(KeyEvent even
14、t) public void keyTyped(KeyEvent event) char keyChar = event.getKeyChar(); int d; if (Charaeter.isUpperCase(keyChar) d = LARGE_INCREMENT; keyChar = Character.toLowerCase(keyChar); else d = SMALL_INCREMENT; （分数：30.00）_计算机二级 JAVA-138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：30.00)1.本题程序的功能是计算 110(包括
15、 1和 10)中除 5以外各个自然数的和。请将下述程序补充完整(注意：不得改动程序的结构，不得增行或删行)。 public class basic public static void main (String args) int i = 1; int sum = 0; while(i = 10) if(i = 5) _; _; _; i+; System.out.println (“sum=“+sum); （分数：30.00）_正确答案：()解析：i+。 continue。 sum=sum+i。二、2简单应用题(总题数：1，分数：40.00)2.本题程序的功能是定义一个简单的计算器，可以进行
16、基本的四则运算。程序中布局了 16个按钮用来表示数字 09 及运算符和点号，程序顶部的文本框用来显示运算数及结果。请将下述程序补充完整(注意：不得改动程序的结构，不得增行或删行)。 import java.awt.*; import java.awt.event.*; import javax.swing.*; public class simple public static void main (String args) try UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName(); catch (Except
17、ion e) JFrame frame = new CalculatorFrame(); frame.show(); class CalculatorPanel extends JPanel implements ActionListener private JTextField display; private JButton btn; private double arg = 0; private String op = “=“; private boolean start = true; public CalculatorPanel() setLayout(new BorderLayou
18、t(); display = new JTextField(“0“); display.setEditable(false); add(display,“North“); JPanel p = new JPanel(); p.setLayout(new GridLayout(4,4); String buttons = “789/456“123-0.= +“; for (int i = 0; i buttons.length(); i +) btn = new JButton(buttons.substring(i,i + 1); p.add(btn); _; add(p,“Center“);
19、 public void actionPerformed(ActionEvent evt) String s = evt.getActionCommand(); if (“0“ = s.charAt(0)s.charAt(0) =“9“ |s.equals(“.“) if (start) display.setText(s); else display.setText(display.getText() + s); start = false; else if (start) if (s.equals(“-“) display.setText(s); start = false; else o
20、p = s; else double x =_; calculate(x); op = s; start = true; public void calculate(double n) if (op.equals(“ + “) arg += n; else if(op.equals(“-“) arg - = n; else if(op.equals(“*“) arg *= n; else if(op.equals(“/“) arg /= n; else if(op.equals(“=“) arg=n; display.setText(“+ arg); class CalculatorFrame
21、 extends Jframe public CalculatorFrame() setTitle(“simple“); setSize(220,180); addWindowListener(new WindowAdapter() public void windowClosing(WindowEvent e) System.exit(0); ); Container contentPane=getContentPane(); contentPane.add(new CalculatorPanel(); （分数：40.00）_正确答案：()解析：btn.addActionListener(t
22、his)。 Double.parseDouble(display.getText()。三、3综合应用题(总题数：1，分数：30.00)3.本题程序的功能是用键盘上的方向键来控制直线的绘制方向。如果一直按向上的方向键，则在窗口中从焦点开始向上缓慢绘制直线，按其他方向的方向键也会向对应的方向缓慢地绘制直线。如果按下 Shift键，绘制直线的速度会加快。请将下述程序补充完整(注意：不得改动程序的结构，不得增行或删行)。 import java.awt.*; import java.awt.geom.*; import java.util.*; import java.awt.event.*; imp
23、ort javax.swing.*; public class advance public static void main(String args) SketchFrame frame = new SketchFrame(); frame.setDefaultCloseOperation(JFrame.EXIT ON CLOSE); frame,show (); class SketchFrame extends JFrame public SketchFrame() setTitle(“advance“); setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT); S
24、ketchPanel panel = new SketchPanel(); Container contentPane = getContentPane(); contentPane.add(panel); public static final int DEFAULT_WIDTH = 300; public static final int DEFAULT_HEIGHT = 200; class SketchPanel extends JPanel _; last = new Point2D.Double(100,100); lines = new ArrayList(); KeyHandl
25、er listener = new KeyHandler(); _; setFocusable(true); public void add(int dx,int dy) Point2D end = new Point2D.Double(last.getX()+ dx,last.getY() + dy); Line2D line = new Line2D.Double(last,end); lines.add(line); repaint(); last = end; public void paintComponent(Graphics g) super.paintComponent(g);
26、 Graphics2D g2 = (Graphics2D)g; for (int i = 0; i lines.size(); i+) g2 .draw (Line2D) lines .get (i); private Point2D last; private ArrayList lines; private static final int SMALL INCREMENT = i; private static final int LARGE_INCREMENT = 5; private class KeyHandler implements KeyListener public void
27、 keyPressed(KeyEvent event) _; int d; if (event.isShiftDown() d = LARGE_INCREMENT; else d = SMALL_INCREMENT; if(keyCode = KeyEvent.VK_LEFT) add(-d,0); else if(keyCode = KeyEvent.VK_RIGHT) add(d,0); else if(keyCode = KeyEvent.VK_UP) add(0,-d); else if(keyCode = KeyEvent.VK DOWN) add(0,d); public void
28、 keyReleased(KeyEvent event) public void keyTyped(KeyEvent event) char keyChar = event.getKeyChar(); int d; if (Charaeter.isUpperCase(keyChar) d = LARGE_INCREMENT; keyChar = Character.toLowerCase(keyChar); else d = SMALL_INCREMENT; （分数：30.00）_正确答案：()解析：public SketchPanel()。 addKeyListener(listener)。 int keyCode=event.getKeyCode()。
