ReviewReview

Review

Concepts

• Comments: definition, example, different types of comments

• Class: definition, example• Object: definition, example• Data type:

– Byte, short, int, long, float, double– Char, boolean– String

Concepts

• Assignment statement• Boolean expressions• Identifiers, constants• Commands:

– If– Switch– Do/While, While, and For

Concepts

• File extension: *.java, *.class• Compile: Textpad: Compile Java and Run

javaDOS: javac and java

Project 1 (Section 01)

• Average: 93.14 (35 students submitted)

Project 1

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100

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Project 1

Project 1 (Section 2)

• Average: 97 (only 28 students submitted)

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101

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Series1

Lab section

Homework 1 (Section 01)

• Avg =84.3. Max = 99.

Section01

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120

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Series1

Homework 1 (Section 02)

• Avg = 88, Max = 100

Section 02

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Series1

Rules for Midterm exam - Student ID is required- Don’t:

- Leave the exam room after the exam is distributed

- Use cell phone or computers (PC)- Talk with each other during the exam

- Limit of questions you can ask teacher during exam time. If you ask more than two questions, you will have some points off taken from your exam.

Answers to Homework 1

1. In general, commands to compile and execute a java program are

a. compile and run b. compile and link c. javac and java d. java and link

This is the only answer accepted if this question is asked in another

exam

Homework 1 - Answer

2. All Java program must have this method to run

a. hello()b. start()c. main()d. method()

Homework 1

• 3. Which of the following is not mandatory in variable declaration

• a. a semicolon • b. an assignment • c. a variable name• d. a data type

Homework1

4. You store java source code files with following extension?

a. .javab. .classc. .srcd. .javadoc

Homework1

5. A single line comment in Java starts with

a. ; b. # c. , d. // e. none of the above

Homework1

6. Java language is case sensitivea. Trueb. False

Homework1

7. As long as a computer has a Java Virtual Machine, the same program written in the Java programming language can run on any computer

a. Trueb. False

Homework1

8. Which of the following is an invalid identifier?

a. oneb. Twoc. _3Fourd. 4Five

Homework1

9. Which of the following is an invalid variable declaration?

a. String inputStr;b. int i=0;c. boolean flag = true;d. double, int, j=0;

Homework110. Assuming the following declarations are

executed in sequence, why are the second and the third declarations invalid?int a,b;double a;double b;

a. Both a and b are invalid identifiers.b. Variable a has been declaredc. Variable b has been declaredd. Both variables a and b have been

declared in the first declaration

Homework1

11. The __new_____operator is used to create a new object

Homework 1

12. Identifiers may not start with a ___number (digit)________ or contain__special/(non-alpha-numeric)_____characters, other than the underscore or the dollar sign

Homework 1

13. char data type represents individual _character______

Homework 1

14. Text data can be stored in _String__objects

Homework 1

15. Constants __can not be (never be, are not)__changed during program execution

Homework 1

16. Boolean expressions are built by use of _relational___operators and _boolean__________operators

Homework 1

17. Every variable that we use in a Java program must be _declared/defined__________

Homework 1

18. A Java program is composed of one or more ___classes__

Homework 1

20. int a== b;== can’t be used in variable

declaration

Homework 121. double monthlyInterestRate;

if (monthlyInterestRate >= 0.08) && (monthlyInterestRate <= 0.5 ); {

System.out.println(“Interest rate is invalid”);System.exit(1);

}1. () is needed or remove )( before and

after &&2. ; should be take out3. No value has been initialized for

monthlyInterestRate

Homework 1

22. char userChoice=’l’;if (userChoice ==’s’) {

System.out.print(“ Drop small cup into position”); (1) Missing ;}else { System.out.println(“ Drop large cup into position”);

}else System.exit(-1);

2. { should be inserted here

Else should be taken out

Homework 1

23. String choice=”5”;switch(choice) {case 4: System.out.println(“ Right branch”); break;default: System.out.println(“ Default branch”); break;}

1. Switch doesn’t support String data type. It must be char or int(bytes,short,int)

Homework 1

24. int sum=0;

for (int i=0, i< 100);{sum+= i;

}1; int i=0, this comma should be semicolon2. Missing post body update (increment or

decrement)3. semicolon after 100) should be taken out

Homework 125. int x,y;

x=-10;y=-20;if ( y>0 && x< y)System.out.println(" The output is "+(x+y));elseSystem.out.println(" The output is "+(x-y));

The output is 10(Because -10-(-20) = -10+20 = 10)

Homework 126. int count=0, sum=0;

while (count < 10) {sum += count;count+=3;

}System.out.println(" Sum ="+ sum);count=0 sum =0count = 3 sum = 0+3=3count = 6 sum = 3+6=9count = 9 sum = 9+9=18

Homework 127. int nextToPrint = 1;

int maximum = 10; while(nextToPrint <= maximum){

if (nextToPrint % 2 != 0) System.out.print(nextToPrint+" ");

nextToPrint = nextToPrint +1; }

System.out.println();

1 3 5 7 9

Homework 128. int sum=0;

int i=0;while (i<5) {

int j=4;while (i!=j) {

sum += j;j=j-1;

}i++;

}System.out.println(" Sum ="+sum);

Sum = 30

Homework 1

• sum=0 i=0• j=4

sum = 0+4 = 4j=3

sum = 4+3 = 7j=2

sum = 7+2 = 9j=1

sum = 9+1=10

Homework 1

• i=1• j=4

sum = 10+4 = 14j=3

sum = 14+3 = 17j=2

sum = 17+2 = 19

Homework 1

• i=2• j=4

sum = 19+4 = 23j=3

sum = 23+3 = 26

Homework 1

• i=3• j=4

sum = 26+4 = 30