scjp-1.htm

详细介绍scjp考试指南包括基础语法和文件读取

          <TD vAlign=top width="13%"><FONT face=Courier>goto&nbsp;</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>package</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>throws</FONT></TD></TR>
        <TR>
          <TD vAlign=top width="13%"><FONT face=Courier>close&nbsp;</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>if</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>private</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>transient</FONT></TD></TR>
        <TR>
          <TD vAlign=top width="13%"><FONT face=Courier>const</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>implements</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>protected</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>try</FONT></TD></TR>
        <TR>
          <TD vAlign=top width="13%"><FONT face=Courier>continue</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>import</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>public</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>void</FONT></TD></TR>
        <TR>
          <TD vAlign=top width="13%"><FONT face=Courier>default</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>instanceof</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>return</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>volatile</FONT></TD></TR>
        <TR>
          <TD vAlign=top width="13%">do</TD>
          <TD vAlign=top width="13%"><FONT face=Courier>integer</FONT></TD>
          <TD vAlign=top width="13%"><FONT face=Courier>short</FONT></TD>
          <TD vAlign=top width="13%"><FONT 
        face=Courier>while</FONT></TD></TR></TBODY></TABLE>&nbsp; 
      <P>Select all valid answers. 
      <OL type=a>
        <LI>superclass 
        <LI>goto 
        <LI>open 
        <LI>close 
        <LI>integer 
        <LI>goto, import 
        <LI>goto, superclass, open, close 
        <LI>they are all valid keywords </LI></OL>
      <P><B>Question 10</B>: Which of the following represents an octal number? 
      <P>Select all that apply. 
      <OL type=a>
        <LI>0x12 
        <LI>32O 
        <LI>032 
        <LI>(octal)2 
        <LI>1 </LI></OL>&nbsp; 
      <P><B>Question 11</B>: What will appear in the standard output when you 
      run the Tester class? 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>class Tester {</FONT> 
            <P><FONT face=Courier>int var;</FONT> 
            <DIR><FONT face=Courier>Tester(double var) {</FONT> 
            <DIR><FONT face=Courier>this.var = (int)var;</FONT></DIR><FONT 
            face=Courier>}</FONT> 
            <P><FONT face=Courier>Tester(int var) {</FONT> 
            <DIR><FONT face=Courier>this("hello");</FONT></DIR><FONT 
            face=Courier>}</FONT> 
            <P><FONT face=Courier>Tester(String s) {</FONT> 
            <DIR><FONT face=Courier>this();</FONT> 
            <P><FONT face=Courier>System.out.println(s);</FONT></P></DIR><FONT 
            face=Courier>}</FONT> 
            <P><FONT face=Courier>Tester() {</FONT> 
            <DIR><FONT 
            face=Courier>System.out.println("good-bye");</FONT></DIR><FONT 
            face=Courier>}</FONT> 
            <P><FONT face=Courier>public static void main(String[] args) 
            {</FONT> 
            <DIR><FONT face=Courier>Tester t = new Tester(5);</FONT></DIR><FONT 
            face=Courier>}</FONT></DIR><FONT 
      face=Courier>}</FONT></TD></TR></TBODY></TABLE>
      <OL type=a>
        <LI>nothing 
        <LI>"hello" 
        <LI>5 
        <LI>"hello" followed by "good-bye" 
        <LI>"good-bye" followed by "hello" </LI></OL>
      <P><B>Question 12</B>: Write a line of code to use the String抯 <FONT 
      face=Courier>substring()</FONT> method to obtain the substring "lip" from 
      a String instance named <FONT face=Courier>s</FONT> that is set to 
      "tulip". 
      <P>Fill in the blank. 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center>&nbsp;</TD></TR></TBODY></TABLE><FONT 
      face=Courier>&nbsp;</FONT> 
      <P><B>Question 13</B>: There are a number of labels in the source code 
      below. These are labeled <FONT face=Courier>a</FONT> through <FONT 
      face=Courier>j</FONT>. Which label identifies the earliest point where, 
      after that line has executed, the object referred to by the variable <FONT 
      face=Courier>first</FONT> may be garbage collected? 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>class Riddle {</FONT> 
            <DIR><FONT face=Courier>public static void main(String[] args) 
            {</FONT> 
            <DIR><FONT face=Courier>String first, second;</FONT> 
            <P><FONT face=Courier>String riddle; 
            <P>if (args.length &lt; 2) 
            <P>return; a: first = new String(args[0]); 
            <P>b: second = new String(args[1]); 
            <P>c: riddle = "When is a " + first; 
            <P>d: first = null; 
            <P>e: riddle += " like a " + second + "?"; 
            <P>f: second = null; 
            <P>g: System.out.println(riddle); 
            <P>h: args[0] = null; 
            <P>i: args[1] = null; 
            <P>j:&nbsp; 
            <DIR>}</DIR>}</FONT></DIR></DIR></TD></TR></TBODY></TABLE>Select the one 
      right answer. 
      <P> 
      <OL type=a>
        <LI><FONT face=Courier>d:</FONT> 
        <LI><FONT face=Courier>e:</FONT> 
        <LI><FONT face=Courier>h:</FONT> 
        <LI><FONT face=Courier>i:</FONT> 
        <LI><FONT face=Courier>j:</FONT> </LI></OL>
      <P><B>Question 14</B>: What are the range of values for a variable of type 
      <TT>byte</TT>? 
      <P>Select the one right answer. 
      <OL type=a>
        <LI>-2<SUP>7</SUP> to 2<SUP>7</SUP> - 1 
        <LI>0 to 2<SUP>7</SUP> 
        <LI>-2<SUP>15</SUP> to 2<SUP>15</SUP> 
        <LI>-2<SUP>15</SUP> to 2<SUP>15</SUP> -1 
        <LI>-2<SUP>15</SUP> - 1 to 2<SUP>15</SUP> </LI></OL>
      <P><B>Question 15</B>: What will happen when you try to compile and run 
      the following program? 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>class Car {</FONT> 
            <DIR><FONT face=Courier>int milesPerGallon;</FONT> 
            <P><FONT face=Courier>int index;</FONT> 
            <P><FONT face=Courier>Car(int mpg) {</FONT> 
            <DIR><FONT face=Courier>milesPerGallon = mpg;</FONT> 
            <P><FONT face=Courier>index = 0;</FONT></P></DIR><FONT 
            face=Courier>}</FONT> 
            <P><FONT face=Courier>Car() {</FONT> 
            <P><FONT face=Courier>}</FONT> 
            <P><FONT face=Courier>public static void main(String[] args) 
            {</FONT> 
            <DIR><FONT face=Courier>int index;</FONT> 
            <P><FONT face=Courier>Car c = new Car(25);</FONT> 
            <P><FONT face=Courier>if (args.length &gt; 0)</FONT> 
            <DIR><FONT face=Courier>if (args[index].equals("Hiway"))</FONT> 
            <DIR><FONT face=Courier>milesPerGallon*= 2;</FONT> <FONT 
            face=Courier>System.out.println("mpg: " + 
            milesPerGallon);</FONT></DIR><FONT face=Courier>}</FONT></DIR><FONT 
            face=Courier>}&nbsp;</FONT></DIR></DIR></TD></TR></TBODY></TABLE>Select 
      the one right answer. 
      <OL type=a>
        <LI>The code compiles and displays "mpg: 50" if the command-line 
        argument is "Hiway". If the command-line argument is not "Hiway", the 
        code displays "mpg: 25". 
        <LI>The code compiles and displays "mpg: 50" if the command-line 
        argument is "Hiway". If the command-line argument is not "Hiway", the 
        code throws an ArrayIndexOutOfBoundsException. 
        <LI>The code does not compile because the automatic variable named <FONT 
        face=Courier>index</FONT> has not been initialized. 
        <LI>The code does not compile because <FONT 
        face=Courier>milesPerGallon</FONT> has not been initialized. 
        <LI>The code does not compile because the no-args constructor is not 
        written correctly. </LI></OL>
      <P><B>Question 16</B>: What will happen when you compile and run this 
      program: 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>class Array {</FONT> 
            <DIR><FONT face=Courier>public static void main(String[] args) 
            {</FONT> 
            <DIR><FONT face=Courier>int length = 100;</FONT> 
            <P><FONT face=Courier>int[] d = new int[length];</FONT> 
            <P><FONT face=Courier>for (int index = 0; index &lt; length; 
            index++)&nbsp;</FONT> 
            <DIR><FONT face=Courier>System.out.println(d[index]);</FONT> <FONT 
            face=Courier>}</FONT></DIR><FONT 
        face=Courier>}</FONT></DIR></DIR></TD></TR></TBODY></TABLE>Select the one 
      right answer. 
      <OL type=a>
        <LI>The code will not compile because the <FONT 
        face=Courier>int[]</FONT> array is not declared correctly. 
        <LI>The code will compile but will throw an 
        IndexArrayOutOfBoundsException when it runs and nothing will appear in 
        the standard output. 
        <LI>The code will display the numbers 0 through 99 in the standard 
        output, and then throw an IndexOutOfBoundsException. 
        <LI>The code will compile but the <FONT face=Courier>println()</FONT> 
        method will throw a NoSuchMethodException. 
        <LI>This code will work fine and display 100 zeroes in the standard 
        output. </LI></OL>
      <P><B>Question 17</B>: What is the result of attempting to compile and run 
      the following class? 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>class Ar {</FONT> 
            <DIR><FONT face=Courier>public static void main(String[] args) 
            {</FONT> 
            <DIR><FONT face=Courier>int[] seeds = new int[3];</FONT> 
            <P><FONT face=Courier>for (int i = 0; i &lt; seeds.length; 
            i++)</FONT> 
            <DIR><FONT face=Courier>System.out.println(i);</FONT> <FONT 
            face=Courier>}</FONT></DIR><FONT 
        face=Courier>}</FONT></DIR></DIR></TD></TR></TBODY></TABLE>Select all 
      valid answers. 
      <P>
      <OL type=a>
        <LI>0 
        <LI>1 
        <LI>2 
        <LI>3 
        <LI>the program does not compile because the seeds array is not 
        initialized </LI></OL>
      <P><B>Question 18</B>: What method name can you use from the applet to 
      read a String passed to an applet via the <FONT 
      face=Courier>&lt;param&gt;</FONT> tag? (Supply the method name only, 
      without parameters.) 
      <P>Fill in the blank. 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT 
      face=Courier>&nbsp;</FONT></TD></TR></TBODY></TABLE>
      <P><B>Question 19</B>: Given these class definitions: 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>class Superclass { }</FONT> 
            <P><FONT face=Courier>class Subclass1 extends Superclass { 
            }</FONT></P></TD></TR></TBODY></TABLE>and these objects: 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>Superclass a = new 
            Superclass();</FONT> 
            <P><FONT face=Courier>Subclass1 b = new 
        Subclass1();</FONT></P></TD></TR></TBODY></TABLE>which of the following 
      explains the result of the statement: 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>a = 
      b;</FONT></TD></TR></TBODY></TABLE>
      <P>Select the one right answer. 
      <P>
      <OL type=a>
        <LI>Illegal at compile time 
        <LI>Legal at compile time but possibly illegal at runtime 
        <LI>Definitely legal at runtime </LI></OL>&nbsp; 
      <P><B><A name=no20>Question 20</A></B>: Given these class definitions: 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>class Superclass { }</FONT> 
            <P><FONT face=Courier>class Subclass1 extends Superclass { }</FONT> 
            <P><FONT face=Courier>class Subclass2 extends Superclass { 
            }</FONT></P></TD></TR></TBODY></TABLE>and these objects: 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>Superclass a = new 
            Superclass();</FONT> 
            <P><FONT face=Courier>Subclass1 b = new Subclass1();</FONT> 
            <P><FONT face=Courier>Subclass2 c = new 
        Subclass2();</FONT></P></TD></TR></TBODY></TABLE>which of the following 
      explains the result of the statement: 
      <TABLE width="100%" border=1>
        <TBODY>
        <TR>
          <TD vAlign=center><FONT face=Courier>b = 
        (Subclass1)c;</FONT></TD></TR></TBODY></TABLE>Select the one right answer.