[IT认证]SCJP认证考试题库3.doc

QUESTION 121 Given: Which code, inserted at line 15, creates an instance of the Point class defined in Line? A. Point p = new Point(); B. Line.Point p = new Line.point(); C. The Point class cannot be instatiated at line 15. D. Line 1 = new Line() ; 1.Point p = new 1.Point(); Answer: ( B ) 静态内部类创建方法 非静态内部类的构造：Line.Point p = new Line().new Point(); 参考大纲：面向对象 — 内部静态类 QUESTION 122 Given: Which statement is true? A. The code will compile without changes. B. The code will compile if public Tree() { Plant(); } is added to the Tree class. C. The code will compile if public Plant() { Tree(); } is added to the Plant class. D. The code will compile if public Plant() { this(fern); } is added to the Plant class. E. The code will compile if public Plant() { Plant(fern); } is added to the Plant class. Answer: ( D ) 子类默认调用父类无参构造函数，而Plant没有无参构造函数，因此须显示调用有参构造函数 参考大纲：面向对象 QUESTION 123 Given: Which two code fragments, inserted independently at line 12, will allow the class to compile? (Choose two.) A. foreach( x ) System.out.print1n(z); B. for( int z : x ) System.out.print1n(z); C. while( x.hashNext() ) System.out.print1n( x.next() ) D. for( int i=0; i x.length; i++ ) System.out.println(x[i]); Answer: ( B, D ) 可变参数方法编译后变成数组参数方法，然后利用循环结构取出数组的值 参考大纲：流程控制和可变长度参数 QUESTION 124 Exhibit: Which statement is true about the classes and interfaces in the exhibit? A. Compilation will succeed for all classes and interfaces. B. Compilation of class C will fail because of an error in line 2. C. Compilation of class C will fail because of an error in line 6. D. Compilation of class AImpl will fail because of an error in line 2. Answer: ( C ) 参考大纲：面向对象 — 复写 QUESTION 125 Place the lines in the correct order to complete the enum。 enum Element { Answer: ( ) enum Element { EARTH, WIND, FIRE{ public String info(){return “Hot”;} }; public String info(){return “element”;} } 列举的内容之后要加上“；” 参考大纲：面向对象 — enum QUESTION 126 Place the code elements in order so that th