Download java homework for grad student and more Assignments Computer Science in PDF only on Docsity!
JAVA Programming Language Homework III － Array, Exception Student ID: Name:
- Given the following Java code:
- class C {
- public static void main(String[] args) {
- int a=0, b=5;
- try {
- System.out.print(a/b+b/a);
- } catch {
- System.out.println(“Exceptions!!!”);
- }
- }
- }
What is the result of attempting to compile the program? A. Prints: Exceptions!!! B. Prints Nothing C. Compiler Error D. Runtime Error E. None of the above
Answer: C
題目中雖然撰寫了 catch 區塊，但並未給予例外類別名稱與建立例外實例，如： catch(ArithmetException e)，所以編譯時即會發生錯誤的情形。
- Given the following Java code:
- class A {
- public static void main(String[] args) {
- int a=0, b=5;
- String c[] = {“A”, “B”, “C”};
- try {
- for(int i=1; i<4; i++) {
- System.out.print(c[i]);
- }
- System.out.print(a/b+b/a);
- }
- catch(ArithmetException e) {
- System.out.println(“D”);
- }
- catch(ArrayIndexOutOfBoundsException e) {
- System.out.println(“E”);
- }
- }
- }
What is the result of attempting to compile the program? A. Prints: ABC B. Prints: ABD C. Prints: BCE D. Prints: BCDE E. Compiler Error
Answer: C
c[1] = ＂B＂, c[2] = ＂C＂, c[3] = 超出陣列索引
- Given the following Java code:
- class A {
- public static void main(String[] args){
- int a=0, b=5;
- String c[] = {“A”, “B”, “C”};
- try {
- System.out.print(c[a/b]);
- try {
- for(int i=0; i<4; i++) {
- System.out.print(c[i]);
- }
- }
- catch (Exception e)
- {
- int res[] = {1, 2, 3, 4, 5};
- System.arraycopy(src, 0, res, 0, src.length);
- for(int i=0; i<res.length; i++) {
- System.out.print(res[i]);
- }
- }
- }
What is the result? A. 10987654321 B. 10987612345 C. 12345612345 D. Compiler error E. Runtime exception
Answer: E
呼叫 arraycopy()時，來源陣列必須比目的陣列元素個數來的少，反則會發生超 出陣列索引的情形。
- Given the following Java code:
- class A {
- public static void main (String[] args) {
- byte a[] = new byte[2];
- long b[] = new long[2];
- float c[] = new float[2];
- Object d[] = new Object[2];
- System.out.print(a[1]+”,”+b[1]+”,”+c[1]+”,”+d[1]);
- }
- }
What is the result? A. Prints: 0,0,0,null B. Prints: 0,0,0.0,null C. Prints: 0,0,0, D. Prints: null,null,null,null
E. The code runs with no output.
Answer: B
此題四個資料型態各宣告了 1 維陣列，並配置 2 個陣列元素空間，並且沒有給予 初始值，故此題目的在於測驗各資料型態的預設初始值情形。
- Given the following Java code:
- class A {
- public static void main(String[] args) {
- int[ ] var1;
- int[5] var2;
- int[] var3;
- int var4[];
- }
- }
What is the result? A. compile-time errors occur at line 3 B. compile-time errors occur at line 4 C. compile-time errors occur at line 5 D. compile-time errors occur at line 6 E. None of the above
Answer: B
若要指定元素個數不可在[]裡寫數值，而是以 new 的方式配置： int[] var2 = new int[5];
- Given the following Java code:
- class A {
- static void my() throws ArithmeticException {
- System.out.print(“A”);
- throw new ArithmeticException(“A”);
- a = b = c = d = x = y = 0;
- z = 1;
- try {
- try {
- switch(z) {
- case 1: throw new B();
- case 2: throw new C();
- case 3: throw new D();
- case 4: throw new Exception();
- }
- a++;
- }
- catch ( C e ) {b++;}
- finally{c++;}
- }
- catch ( B e ) {d++;}
- catch ( Exception e ) {x++;}
- finally {y++;}
- System.out.print(a+”,”+b+”,”+c+”,”+d+”,”+x+”,”+y);
- }
- }
What is the result? A. 0,0,1,1,0, B. 0,1,0,1,1, C. 0,0,1,1,0, D. 0,1,1,1,1, E. 1,1,0,1,0,
Answer: A
- 初始化 a, b, c, d, x, y 為 0，z 為 1
- 進入 switch，case 1，丟出例外 B
- catch(C e)無法捕捉，進入第二層的 finally，執行 c++: c=
- 將例外往上丟
- 被 catch (B e)捕捉，執行 d++: d=
- 略過 catch (Exception e)，離開第一層的 try
- 進入第一層的 finally，執行 y++: y= 故結果為： 0,0,1,1,0,
- Given the following Java code:
- class B extends Exception {
- public void myMethod( ) throws RuntimeException {}
- }
- class A extend B{
- public void myMethod( ) throws Exception {}
- public static void main (String[] args) {}
- }
Compile-time errors occur at which lines? A. 1 B. 2 C. 6 D. 7 E. None of the above
Answer: C
由於所丟出的 Exception 類別比原來方法所丟出的 RuntimeException 的涵蓋範 圍還大，所以在 A 類別裡覆寫 myMethod( )是不合法的作法。
- Given the following Java code:
- class A {
- public static void main (String[] args) {
- int a=1, b=0;
- int c[] = {1,2,3};
- try {
- System.out.print(c[1]);
- try {
- System.out.print(a/b+b/a);
- }
- catch (ArithmeticException e)
- {
- System.out.print(“C”);
- }
