CSE 174 Exam 3

whats higher in precedence &&/|| or !?

!

How do you get the last digit of a number?

%10

write and expression that returns a random integer between 50 and 99, bot inclusive

(int) (Math.random () *50) + 50

the file produced by the java compiler has what extension?

.class

what method should you use to compare strings ?

.equals()

int x=1; (x>==1) || (x++>1) whats the value of x after the evaluation of the expression

1 because if the 1st one is true it doesn't even read the second part

How to use Math.random() to produce from 1 to 9?

1+(int) (Math.random()*9)

what is the value after the code is executed? int num=5, ans=1; num=ans++; num=? ans=?

1,2

int num1= 10; if(num1==10){ int num2=11; system.out.println(num1+" " +num2); } int num2=12; System.out.println(num1+ " " + num2);

10,11 10,12

int 101-1/10=?

101

what is the size of a char data type in java

16 bits

what is the output? for x=2 System.out.print("A"); if(x==2){ System.out.print("B"); } if(x==3){ System.out.print("C"); } else{ System.out.print("D"); } System.out.print("E);

ABDE

which of the following is a valid initialization of a Boolean variable? A) boolean flag=0; B) boolean flag=true; C)boolean flag=no; D) boolean flag= "true";

B

what does the following code snippet print? int a=10, b=20, c; c=b/a if(c>0){ int ab; ab =a*b+c; } System.out.print(ab);

Error: cant find symbol; variable ab

what is the output of the code boolean isStudying = false; if("true") is studying=true;

Error: incompatible types

What is a runtime error also known as?

Exception

T or F in java 1/3+1/3+1/3 = (1+1+1)/3

False

what is the boolean expression in java of (0.1+0.1+0.1==0.3)

False

java's predefined classes are grouped into what?

Packages

what does %s do in print f

String Capital S will uppercase all the letters in a string

What is variable?

a named storage location in the computers memory. ( ie System.out.print(value);)

What is literal?

a value that is written into the code of a program

int x=11; int y=14; if(x>10){ System.out.println("a"); if(x>10){ System.out.println("b"); } } else if(y>10){ if(x==1) System.out.println("c"); }

a,b

double x=2.0; if(x==2.0) System.out.println("a"); if(x==3.0) System.out.println("b"); else System.out.println("c");

a,c

what data type is returned by equals() method of the String class?

boolean

what do you need in a switch statement in order to stop it from going through all the lines of code?

break;

What are the 8 primitive data types?

byte short int long float double boolean char

what does \" do?

causes a double quotation mark to be printed

what does \' do?

causes a single quotation mark to be printed

what does \\ do ?

causes one backslash to be printed

what does compareTo() method do?

compare lexicology of the words

what does equalsIgnoreCase() do?

compares the string ignoring the case of it

What is Logic Errors?

compilers and runs, but with unexpected results

what is Runtime Errors?

compiles, but then crash/ not discovered by the compiler

what does %d do in printf

decimal integer

what does declaring a variable do?

declaring gives the data type and name of the variable

what does void in a method do?

doesnt return anything, usually prints something

What is the order of java program development ?

editor to source code(.java) to java compiler to Byte code(.class) to JVM to program execution

what is compiler Errors?

error that prevents the program from compiling

int num=10; if(num%2==0){ String result="even"; } else{ String result="odd"; } System.out.println(result);

error, because result wasn't declared before the if statement

what is the default initialization of a boolean variable?

false

what does %f do in printf

floating-point number

Byte Code

generated by the compiler(.class file)

what does str.charAt() do?

gives the character at the position inputted

what does str.length() do?

gives the length of the string

what doe substring() do?

gives the substring of the specific word. From the first number to the position before the last number

compiler

identifies syntax Errors and a program that converts a program in one language to another language

How do you import the Scanner class in Java?

import java.util.Scanner;

Java Virtual Machine

interprets the Byte code

What is an IDE ?

it combines an editor, compiler, and interpreter into one package

what does initializing a variable do ?

it gives the variable a value

what is narrow casting ?

its casting that requires explicit type casting because the target type is smaller than the source type

identifiers may only contain

letters a-z or A-Z, the digits 0-9, underscores(_) or $, the first character cant be a digit, no space, and are case sensitive

Are all java reserved words in uppercase or lowercase

lowercase

what does %n do in printf

newline

void test1 (int x){ System.out.println(x); } wil int a=test1(2); work? if so whats the answer?

no because a cant equal a print statement

double test3 (double y){ return y+2; } will int d= test3(4.5); work?

no because d is an int and it returns a double

String test2(int x){ return "Java " + x; } will String s= test2(10.0) work?

no because you cant have a double when the parameters are int

void test1 (int x){ System.out.println(x); } wil System.out.println(test1(3)); work? if so whats the answer?

no because you cant print a print

String test2(int x){ return "Java " + x; } will int c = test2(40); work?

no, you cant have something equal to a word and number

how would you get 'g' from the following definition? String str ="strings";

str.charAt(str.length()-2);

what does str.indexOf() return ?

the 1st index of the input inside of (). If it cant find it it returns -1

what is Scope?

the parts of the program where the variable is visible

what does a method use to call the value back to the calling method

the return statement

what is the output of the code int num=0; System.out.println(num>=0 || 10/num>=0);

true

int x=1; System.out.println((x!=1) == !(x==1)); System.out.println((X>0) || (x<0)); System.out.println((x>0) && (x<0));

true,true,false

what does the Datatype.parseDatatype() do?

turns the inputted string in () to whatever data type is being used

block level variables

variables declared inside a block

local variables

variables declared inside a method

what is the return type of this method? public static void main (String[] args);

void

what is lifetime?

when a variable is born and when it dies

what is widening casting?

widening conversions are automatic type casting

double test4( int x, int y){ return x+y; } will System.out.print(test4(5,6)); work?

yes, 11.0

double test4( int x, int y){ return x+y; } will int g= (int)test4(1,2); work?

yes, 3

double test3 (double y){ return y+2; } will double e = test3(5); work?

yes, 7.0

double test4( int x, int y){ return x+y; } will double g= test4(3,4); work?

yes, 7.0

double test3 (double y){ return y+2; } will double f = test3(6.5);; work?

yes, 8.5

void test1 (int x){ System.out.println(x); } wil test(1); work? if so whats the answer?

yes,1

Applets

small applications that require the use of a java enabled web browser

what would a.compareTo(b) be?

<0 because a is before b

int x=1; (x>==1) && (x++>1) whats the value of x after the evaluation of the expression

2

what is the output? a=10 b=2 c=3 d=4 e=5 a=a>b?c>d?1:e<d?2:3:4;

2

what value of c belongs in the blank line int x=10; int c= ___; // line 2 switch(c){ case1: x+=2; case2: x+=2; defult: x+=1; } System.out.println(x); //prints 13

2

what are the values printed after the snippet is executed? int val1=2; double val2=++vall * 10 +2.0; val1=? val2=?

3,32.0

what is the value of '1'?

49

what does %c do in printf

Character Capital C will uppercase the letter

What is the interpreter in java and what does it do?

JVM it converts one line of code from one language to another than executes the the instructions

String test2(int x){ return "Java " + x; } will System.out.println(test2(10)); work?

Java 10

write an expression to check if the double values a and b are very close together

Math.abs(a-b)<.0001

what Math method will produce an answer that is closest in value to a double d, while not being greater than d in int floor

Math.floor

what does contains() do?

sees if a string contains the other string in it

an if statement must have a boolean expression and that boolean expression must be enclosed in parentheses ?

True

What are the rules for naming a class?

Uppercase letter to start it, no spaces

how do you create a method?

public static (return type) (method name)(argument type & argument variable){ }

How do you create a Constant?

put final at the beginning then the data type then uppercase name separated by an underscore

write a method that returns 0 if the boolean argument boobs is false, 1 otherwise

return (boobs==true)?1:0;

write a return method that returns the int sum of the arguments int num1 and double num2

return (int) (num1+num2);

write a return method that returns the length of the longest string of S1 and S2

return s1.length()>s2.length?s1.length():s2.length();

write a method that returns only the first letters of the two string arguments str1 and str2

return str1.substring(0,1)+str2.substring(0,1);

write a method that returns if at least one of the arguments num1 and num2 is greater than but not equal to 50 and the sum of the two numbers is even and returns false otherwise

return(num1>50 ||num2>50) && ( (num1+num2) %2==0);