2011年JAVA认证模拟题第二阶段（8）

会计考友

　　Q22.Assume the the class AcLis implements the ActionListener interface. The code fragment below constructs a button ande gives it four action listeners. When the button is pressed, which action listener is the first to get its actionPerformed() method invoked?
- U) g$ r( D) ~( E+ s7 ]8 o7 W　　1. Button btn = new Button(“Hello”);
　　2. AcLis a1 = new AcLis();
2 v  O, z  i/ k" ]6 z5 [  a  I+ M　　3. AcLis a2 = new AcLis();
: v% q5 ^# a% w　　4. AcLis a3 = new AcLis();
　　5. btn.addActionListener(a1);
　　6. btn.addActionListener(a2);
　　7. btn.addActionListener(a3);
　　8. btn.removeActionListener(a2);
7 P, e: f$ c+ X7 J　　9. btn.removeActionListener(a3);
　　10. btn.addActionListener(a3);
* ~/ S; ^" h0 {% T5 o" u$ l5 L　　11. btn.addActionListener(a2);
0 F( V7 t- m9 ?( ~: o5 R# j　　a. a1 gets its actionPerformed() method invoked first.
　　b. a2 gets its actionPerformed() method invoked first.
3 ^9 N9 }* m4 u& M; ^$ Q　　c. a3 gets its actionPerformed() method invoked first.
　　d. It is impossible to know which listener will be first.
　　Q23.Which statement or statements are true about the code listed below?
5 T0 Z  Y: d0 A! I4 |! U$ f　　1. public class MyTextArea extends TextArea {
　　2. public MyTextArea(int nrows, int ncols) {
　　3. enableEvents(AWTEvent.TEXT_EVENT_MASK);
　　4. ｝
　　5. public void processTextEvent(TextEvent te) {
, {+ @& F! G, \) l8 F
　　6. System.out.println(“Processing a text event”);

会计考友

</p>　　7. ｝
　　8. ｝
　　a. The source code must appear in a file called MyTextArea.java.
  j8 Q; j/ ~" x& B" T$ P0 F　　b. Between lines 2 and 3, a call should be made to super(nrows,ncols) so that the next component will have the correct size.
　　c. Between lines 6 and 7, the following code should appear “return true;”
  I1 d( P& \" n" R　　d. Between lines 6 and 7, the following code should appear “super.processTextEvent(te);”
* `- l- x% ^6 `% w3 Q　　Q24.Which statement or statements are true about the code fragment listed below? (HINT The ActionListener and ItemListener interface each define a single method.)
　　1. class MyListener implements ActionListener, ItemListener {
- v1 q2 j2 D5 S% _6 d　　2. public void actionPerformed(ActionEvent e) {
, B  O) z. o+ z, G0 S　　3. System.out.println(“Action.”);
　　4. ｝
' j. S/ [& H. v$ I2 _8 e! s- Z　　5. public void itemStateChanged(ItemEvent ie) {
% e( G) F  V; L　　6. System.out.println(“Item.”);
　　7. ｝
　　8. ｝
　　a. The code compiles without error.
　　b. The code generates a compiler error at line 1.
　　c. The code generates a compiler error at line 2.
　　d. The code generates a compiler error at line 5.
6 [- X& L4 l* M4 K' z　　22. d
  x6 x9 h/ p& S9 y　　23. abd
　　24. a