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Java.lang Class Online Exam Quiz

Important questions about Java.lang Class. Java.lang Class MCQ questions with answers. Java.lang Class exam questions and answers for students and interviews.

1. What will be the output of the program? interface Foo141 { int k = 0; /* Line 3 */ } public class Test141 implements Foo141 { public static void main(String args[]) { int i; Test141 test141 = new Test141(); i = test141.k; /* Line 11 */ i = Test141.k; i = Foo141.k; } }

Options

A : Compilation fails.

B : Compiles and runs ok.

C : Compiles but throws an Exception at runtime.

D : Compiles but throws a RuntimeException at runtime.

2. What will be the output of the program? class Q207 { public static void main(String[] args) { int i1 = 5; int i2 = 6; String s1 = "7"; System.out.println(i1 + i2 + s1); /* Line 8 */ } }

Options

A : 18

B : 117

C : 567

D : Compiler error

3. What will be the output of the program? String s = "hello"; Object o = s; if( o.equals(s) ) { System.out.println("A"); } else { System.out.println("B"); } if( s.equals(o) ) { System.out.println("C"); } else { System.out.println("D"); } A B C D

Options

A : 1 and 3

B : 2 and 4

C : 3 and 4

D : 1 and 2

4. What will be the output of the program? public class ObjComp { public static void main(String [] args ) { int result = 0; ObjComp oc = new ObjComp(); Object o = oc; if (o == oc) result = 1; if (o != oc) result = result + 10; if (o.equals(oc) ) result = result + 100; if (oc.equals(o) ) result = result + 1000; System.out.println("result = " + result); } }

Options

A : 1

B : 10

C : 101

D : 1101

5. What will be the output of the program? public class Example { public static void main(String [] args) { double values[] = {-2.3, -1.0, 0.25, 4}; int cnt = 0; for (int x=0; x < values.length; x++) { if (Math.round(values[x] + .5) == Math.ceil(values[x])) { ++cnt; } } System.out.println("same results " + cnt + " time(s)"); } }

Options

A : same results 0 time(s)

B : same results 2 time(s)

C : same results 4 time(s)

D : Compilation fails.

6. What will be the output of the program? class Tree { } class Pine extends Tree { } class Oak extends Tree { } public class Forest1 { public static void main (String [] args) { Tree tree = new Pine(); if( tree instanceof Pine ) System.out.println ("Pine"); else if( tree instanceof Tree ) System.out.println ("Tree"); else if( tree instanceof Oak ) System.out.println ( "Oak" ); else System.out.println ("Oops "); } }

Options

A : Pine

B : Tree

C : Forest

D : Oops

7. What will be the output of the program? public class WrapTest { public static void main(String [] args) { int result = 0; short s = 42; Long x = new Long("42"); Long y = new Long(42); Short z = new Short("42"); Short x2 = new Short(s); Integer y2 = new Integer("42"); Integer z2 = new Integer(42); if (x == y) /* Line 13 */ result = 1; if (x.equals(y) ) /* Line 15 */ result = result + 10; if (x.equals(z) ) /* Line 17 */ result = result + 100; if (x.equals(x2) ) /* Line 19 */ result = result + 1000; if (x.equals(z2) ) /* Line 21 */ result = result + 10000; System.out.println("result = " + result); } }

Options

A : result = 1

B : result = 10

C : result = 11

D : result = 11010

8. What will be the output of the program? String x = "xyz"; x.toUpperCase(); /* Line 2 */ String y = x.replace('Y', 'y'); y = y + "abc"; System.out.println(y);

Options

A : abcXyZ

B : abcxyz

C : xyzabc

D : XyZabc

9. What will be the output of the program? public class StringRef { public static void main(String [] args) { String s1 = "abc"; String s2 = "def"; String s3 = s2; /* Line 7 */ s2 = "ghi"; System.out.println(s1 + s2 + s3); } }

Options

A : abcdefghi

B : abcdefdef

C : abcghidef

D : abcghighi

10. What will be the output of the program? int i = (int) Math.random();

Options

A : i = 0

B : i = 1

C : value of i is undetermined

D : Statement causes a compile error

1. What will be the output of the program? int i = 1, j = 10; do { if(i++ > --j) /* Line 4 */ { continue; } } while (i < 5); System.out.println("i = " + i + "and j = " + j); /* Line 9 */

Options

A : i = 6 and j = 5

B : i = 5 and j = 5

C : i = 6 and j = 6

D : i = 5 and j = 6

2. What will be the output of the program? String d = "bookkeeper"; d.substring(1,7); d = "w" + d; d.append("woo"); /* Line 4 */ System.out.println(d);

Options

A : wookkeewoo

B : wbookkeeper

C : wbookkeewoo

D : Compilation fails.

3. What will be the output of the program? System.out.println(Math.sqrt(-4D));

Options

A : -2

B : NaN

C : Compile Error

D : Runtime Exception

4. What will be the output of the program? public class NFE { public static void main(String [] args) { String s = "42"; try { s = s.concat(".5"); /* Line 8 */ double d = Double.parseDouble(s); s = Double.toString(d); int x = (int) Math.ceil(Double.valueOf(s).doubleValue()); System.out.println(x); } catch (NumberFormatException e) { System.out.println("bad number"); } } }

Options

A : 42

B : 42.5

C : 43

D : bad number

5. What will be the output of the program? String s = "ABC"; s.toLowerCase(); s += "def"; System.out.println(s);

Options

A : ABC

B : abc

C : ABCdef

D : Compile Error

6. What will be the output of the program? public class ExamQuestion6 { static int x; boolean catch() { x++; return true; } public static void main(String[] args) { x=0; if ((catch() | catch()) || catch()) x++; System.out.println(x); } }

Options

A : 1

B : 2

C : 3

D : Compilation Fails

7. What will be the output of the program? try { Float f1 = new Float("3.0"); int x = f1.intValue(); byte b = f1.byteValue(); double d = f1.doubleValue(); System.out.println(x + b + d); } catch (NumberFormatException e) /* Line 9 */ { System.out.println("bad number"); /* Line 11 */ }

Options

A : 9.0

B : bad number

C : Compilation fails on line 9.

D : Compilation fails on line 11.

1. What will be the output of the program? class A { public A(int x){} } class B extends A { } public class test { public static void main (String args []) { A a = new B(); System.out.println("complete"); } }

Options

A : It compiles and runs printing nothing

B : Compiles but fails at runtime

C : Compile Error

D : Prints "complete"

2. What will be the output of the program? public class Test138 { public static void stringReplace (String text) { text = text.replace ('j' , 'c'); /* Line 5 */ } public static void bufferReplace (StringBuffer text) { text = text.append ("c"); /* Line 9 */ } public static void main (String args[]) { String textString = new String ("java"); StringBuffer textBuffer = new StringBuffer ("java"); /* Line 14 */ stringReplace(textString); bufferReplace(textBuffer); System.out.println (textString + textBuffer); } }

Options

A : java

B : javac

C : javajavac

D : Compile error

3. What will be the output of the program? public class Test178 { public static void main(String[] args) { String s = "foo"; Object o = (Object)s; if (s.equals(o)) { System.out.print("AAA"); } else { System.out.print("BBB"); } if (o.equals(s)) { System.out.print("CCC"); } else { System.out.print("DDD"); } } }

Options

A : AAACCC

B : AAADDD

C : BBBCCC

D : BBBDDD

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