多项选择题
Given two collection objects referenced by col1 and col2，which of these statements are true？（）
A.The operation col1.retainAll（col2） will not modify the col1 object.
B.The operation col1.removeAll（col2） will not modify the col2 object.
C.The operation col1.addAll（col2） will return a new collection object， containing elements from both col1 and col2.
D.The operation col1.containsAll（Col2） will not modify the col1 object.
相关考题
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多项选择题
Which statements concerning the following code are true？（） class a { public a（） {} public a（int i） { this（）； } } class b extends a { public boolean b（String msg） { return false； } } class c extends b { private c（） { super（）； } public c（String msg） { this（）； } public c（int i） {} }
A.The code will fail to compile.
B.The constructor in a that takes an int as an argument will never be called as a result of constructing an object of class b or c.
C.Class c has three constructors.
D.Objects of class b cannot be constructed.
E.At most one of the constructors of each class is called as a result of constructing an object of class c. -
多项选择题
Which expressions will evaluate to true if preceded by the following code？（） String a = "hello"； String b = new String（a）； String c = a； char[] d = { ’h’， ’e’， ’l’， ’l’， ’o’ }；
A.（a == "Hello"）
B.（a == b）
C.（a == c）
D.a.equals（b）
E.a.equals（d） -
单项选择题
What will be the result of attempting to run the following program？（） public class Qaa75 { public static void main（String args[]） { String[][][] arr = { { {}， null }， { { "1"， "2" }， { "1"， null， "3" } }， {}， { { "1"， null } } }； System.out.println（arr.length + arr[1][2].length）； } }
A.The program will terminate with an ArrayIndexOutOfBoundsException.
B.The program will terminate with a NullPointerException.
C.4 will be written to standard output.
D.6 will be written to standard output.
E.7 will be written to standard output.
