Q 1 : What is the output?
[code lang=”java”]
import java.util.*;
public class Test1{
public static void main(String a[]){
Set s = new TreeSet();
s.add(new Person(20));
s.add(new Person(10));
System.out.println(s);
}
}
class Person{
Person(int i){}
}
[/code]
Choose the one below:
- 10 20
- ClassCastException
- Compiler Error
- Compiler Error
Q 2 : What is the output?
[code lang=”java”]
import java.util.*;
public class Test2{
public static void main(String a[]){
Map s = new Hashtable();
s.put(null,null);
System.out.println(s);
}
}
[/code]
Choose the one below:
- [null = null]
- NullPointerException
- null
- []
Q 3 : What is the output?
[code lang=”java”]
import java.util.*;
public class Test3{
public static void main(String a[]){
Map s = new WeakHashMap(10);
s.put(null,null);
System.out.println(s);
}
}
[/code]
Choose the one below:
- [null = null]
- NullPointerException
- null
- []
Q 4 : What is the output?
[code lang=”java”]
import java.util.*;
public class Test4{
public static void main(String a[]){
Map s = new LinkedHashMap();
s.put("1","one");
s.put("3","three");
s.put("2","two");
System.out.println(s);
}
}
[/code]
Choose the one below:
- [1=one,3=three,2=two]
- NullPointerException
- [1=one,2=two,3=three]
- []
Q 5 : What is the output?
[code lang=”java”]
import java.util.*;
public class Test5{
public static void main(String a[]){
Map s = new HashMap();
s.put("1","one");
s.put("3","three");
s.put("2","two");
System.out.println(s);
}
}
[/code]
Choose the one below:
- [1=one,3=three,2=two]
- [3=three,2=two,1=one]
- cannot predict the order
- []
Q 6 : What is the output?
[code lang=”java”]
public class Test6{
public static void method(float f){
System.out.println("Float");
}
public static void method(double f){
System.out.println("Double");
}
public static void main(String a[]){
float f1 = 2.0f;
float f2 = 2.0f;
method(1.0);
method(1.0f);
method(1.0f*2.0f);
method(1.0f*2.0);
method(f1*f2);
}
}
[/code]
Choose the one below:
- Double Double Double Double Double
- Float Float Float Float Float
- Double Float Float Double Float
- Double Float Float Double Double
Q 7 : What is the output?
[code lang=”java”]
public class Test7{
public static void method(byte b){
System.out.println("Byte");
}
public static void method(int i){
System.out.println("Int");
}
public static void main(String a[]){
byte b = 1;
method(1);
method(128);
method((byte)128);
method(b);
}
}
[/code]
Choose the one below:
- Byte Int Int Byte
- Byte Int Int Byte
- Byte Int Byte Byte
- Int Int Byte Byte
Q 8 : Which of the following are correct?
[code lang=”java”]
public class Test8{
public static void main(String a[]){
byte b = 1;
char c = 2;
short s = 3;
int i = 4;
c = b; // 1
s = b; // 2
i = b; //3
s = c * b; //4
}
}
[/code]
Choose the one below:
- Error at mark 1
- Error at mark 2
- Error at mark 3
- Error at mark 4
Q 9 : Which of the following are correct?
[code lang=”java”]
public class Test9{
public static void main(String a[]){
final byte b = 1;
char c = 2;
short s = 3;
int i = 4;
c = b; // 1
s = b; // 2
i = b; //3
s = c * b; //4
}
}
[/code]
Choose the one below:
- Error at mark 1
- Error at mark 2
- Error at mark 3
- Error at mark 4
Q 10 : What is output?
[code lang=”java”]
public class Test10{
public static void main(String a[]){
String s1 = "Sun";
String s2 = "Java";
s1.concat(s2);
System.out.println(s1);
}
}
[/code]
Choose the one below:
- Sun
- Java
- SunJava
- JavaSun
Q 11 : What is output?
[code lang=”java”]
public class Test11{
public static void main(String a[]){
Integer i1 = new Integer(127);
Integer i2 = new Integer(127);
Long l = new Long(127);
System.out.println(i1 == i2);
System.out.println(i1.equals(i2));
System.out.println(i1.equals(l));
}
}
[/code]
Choose the one below:
- false true true
- true true true
- false true false
- Compiler Error
Q 12 : What is output?
[code lang=”java”]
public class Test12{
public static void main(String a[]){
byte b = 100;
Byte b1= new Byte(100);
Byte b2 = new Byte(b);
System.out.println(b1 == b2);
System.out.println(b1.equals(b2));
}
}
[/code]
Choose the one below:
- false true
- true false
- true true
- Compiler Error
Q 13 : What is output?
[code lang=”java”]
public class Test13{
public static void method(String s){
System.out.println("String Version");
}
public static void method(StringBuffer sb){
System.out.println("String Buffer Version");
}
public static void main(String a[]){
method(null);
}
}
[/code]
Choose the one below:
- String Version
- String Buffer Version
- Runtime Exception
- Compiler Error
Q 14 : What is output?
[code lang=”java”]
public class Test14{
static String s ="Instance";
public static void method(String s){
s+="Add";
}
public static void main(String a[]){
Test14 t = new Test14();
s = "New Instance";
String s = "Local";
method(s);
System.out.println(s);
System.out.println(t.s);
}
}
[/code]
Choose the one below:
- Local Instance
- Local New Instance
- Local Add New Instance
- Compiler Error
Q 15 : What is output?
[code lang=”java”]
public class Test15{
public static void method(StringBuffer sb){
sb.append(" Added");
sb = new StringBuffer("Hai");
}
public static void main(String a[]){
StringBuffer sb = new StringBuffer("String Buffer");
method(sb);
System.out.println(sb);
}
}
[/code]
Choose the one below:
- String Buffer
- String Buffer Added
- Hai
- Compiler Error
Q 16 : What is output?
[code lang=”java”]
public class Test16{
public static void method(StringBuffer sb){
sb = new StringBuffer("Hai");
sb.append(" Added");
}
public static void main(String a[]){
StringBuffer sb = new StringBuffer("String Buffer");
method(sb);
System.out.println(sb);
}
}
[/code]
Choose the one below:
- String Buffer
- String Buffer Added
- Hai
- Compiler Error
Q 17 : What is output?
[code lang=”java”]
import java.util.*;
public class Test17{
public static void main(String a[]){
Map m = new Hashtable(10,0.75f);
System.out.println(m.size());
}
}
[/code]
Choose the one below:
- 10
- 7
- cOMPILER eRROR
Q 18 : What is the default capacity of java.util.Hashtable?
- 10
- 16
- 11
- 20
Q 19 : What is the default capacity of java.util.HashMap?
- 10
- 16
- 11
- 20
Q 20 : Which of the following classes has synchronized methods?
- ArrayList
- Vector
- HashTable
- WeakHashMap
Q 21 : What is output?
[code lang=”java”]
public class Test21{
public static void main(String a[]){
String s1 = new String("Hai");
String s2 = "Hai";
String s3 = new String("Hai").intern();
System.out.println(s1 == s2);
System.out.println(s1 == s3);
System.out.println(s2 == s3);
}
}
[/code]
Choose the one below:
- false false true
- true false true
- false false false
- false true true
Q 22 : What is output?
[code lang=”java”]
public class Test22{
public static void main(String a[]){
String s1 = "SunMicroSystems";
System.out.println(s1.substring(0));
System.out.println(s1.substring(1,4));
System.out.println(s1.substring(8));
}
}
[/code]
Choose the one below:
- SunMicrosystems sun oSystem
- SunMicrosystems unM Systems
- StringIndexOutOfBoundsException
- None Of the above
Q 23 : What is output?
[code lang=”java”]
public class Test23{
public static void main(String a[]){
String s1 = "Sun";
System.out.println(s1.substring(5));
}
}
[/code]
Choose the one below:
- -1
- 0
- StringIndexOutOfBoundsException
- ArrayIndexOutOfBoundsException
Q 24 : Which of the following are static methods in java.lang.String class?
- valueOf
- length
- indexOf
- All the above.
Q 25 : What is output?
[code lang=”java”]
public class Test25{
public static void main(String a[]){
StringBuffer sb = new StringBuffer(8);
sb.append("TestString");
System.out.println(sb.capacity());
System.out.println(sb.length());
}
}
[/code]
Choose the one below:
- 8 10
- 10 10
- 18 10
- 18 18
Answers
Q 1 : 2 is correct. ClassCastException.
Q 2 : 2 is correct. NullPointerException.
Q 3 : 1 is correct. [null = null].
Q 4 : 1 is correct. [1=one,3=three,2=two].
Q 5 : 3 is correct. cannot predict the order.
Q 6 : 3 is correct. Double Float Float Double Float.
Q 7 : 4 is correct. Int Int Byte Byte.
Q 8 : 1 is correct. Error at mark 1.
4 is correct. Error at mark 4.
Q 9 : 4 is correct. Error at mark 4.
Q 10 : 1 is correct. Sun.
Q 11 : 3 is correct. false true false.
Q 12 : 4 is correct. Compiler Error.
Q 13 : 4 is correct. Compiler Error.
Q 14 : 2 is correct. Local New Instance.
Q 15 : 2 is correct. String Buffer Added.
Q 16 : 1 is correct. String Buffer.
Q 17 : 1 is correct. 0.
Q 18 : 3 is correct. 11.
Q 19 : 2 is correct. 16.
Q 20 : 2 is correct. Vector.
3 is correct. HashTable.
Q 21 : 1 is correct. false false true.
Q 22 : 2 is correct. SunMicrosystems unM Systems.
Q 23 : 3 is correct. StringIndexOutOfBoundsException.
Q 24 : 1 is correct. valueOf.
Q 25 : 3 is correct. 18 10.
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