bai giang java co ban - java cơ bản - bai 2
DESCRIPTION
bài giảng java cơ bản, bài 2/5. Nơi giảng: VTC academy Người giảng: Hoàng Văn HậuTRANSCRIPT
Introduction toJava Programming
Y. Daniel LiangEdited by Hoàng Văn Hậu – VTC Academy – THSoft co.,ltd
https://play.google.com/store/apps/developer?id=THSoft+Co.,Ltd
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Introduction
Course Objectives Organization of the Book
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Course Objectives Upon completing the course, you will understand
– Create, compile, and run Java programs
– Primitive data types
– Java control flow
– Methods– Arrays (for teaching Java in two semesters, this could be the end)
– Object-oriented programming
– Core Java classes (Swing, exception, internationalization, multithreading, multimedia, I/O, networking, Java Collections Framework)
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Course Objectives, cont.
You will be able to – Develop programs using Eclipse IDE– Write simple programs using primitive data
types, control statements, methods, and arrays.– Create and use methods– Write interesting projects
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Session 02: Control statement
Swith Case statement While, do while statement For statement Continue, break, return Array in Java String in Java Exception and debuging
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switch Statementsswitch (year) { case 7: annualInterestRate = 7.25; break; case 15: annualInterestRate = 8.50; break; case 30: annualInterestRate = 9.0; break; default: System.out.println( "Wrong number of years, enter 7, 15, or 30");}
Eclipse shortcut key:S + Ctrl + Space
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switch Statement Flow Chart
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switch Statement RulesThe switch-expression must yield a value of char, byte, short, or int type and must always be enclosed in parentheses.
The value1, ..., and valueN must have the same data type as the value of the switch-expression. The resulting statements in the case statement are executed when the value in the case statement matches the value of the switch-expression. (The case statements are executed in sequential order.)
The keyword break is optional, but it should be used at the end of each case in order to terminate the remainder of the switch statement. If the break statement is not present, the next case statement will be executed.
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switch Statement Rules, cont.
The default case, which is optional, can be used to perform actions when none of the specified cases is true. The order of the cases (including the default case) does not matter. However, it is a good programming style to follow the logical sequence of the cases and place the default case at the end.
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Actions on Eclipse
Open Eclipse IDE– Create project: Session2Ex– Create java class: Ex2WithSwitch.java
RunRunSourceSource
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Repetitions
while Loops
do-while Loops for Loops
break and continue
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while Loop Flow Chartwhile (continuation-condition) {
// loop-body;
}
Eclipse shortcut key:w + Ctrl + Space
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while Loop Flow Chart, cont.
int i = 0;while (i < 100) { System.out.println( "Welcome to Java!"); i++;}
false
true
System.out.println("Welcoem to Java!"); i++;
Next Statement
(i < 100)
i = 0;
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do-while Loop
false
true
Statement(s)
NextStatement
Continue condition?
do {
// Loop body;
} while (continue-condition);
Eclipse shortcut key:d + Ctrl + Space
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for Loopsfor (initial-action; loop-continuation-condition;
action-after-each-iteration) { //loop body;}
int i = 0;while (i < 100) { System.out.println("Welcome to Java! ” + i); i++; }
Example:
int i;for (i = 0; i < 100; i++) { System.out.println("Welcome to Java! ” + i); }
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for Loop Flow Chartfor (initial-action; loop-continuation-condition; action-after-each-iteration) { //loop body;}
Eclipse shortcut key:f + Ctrl + Space
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Actions on Eclipse Open Eclipse IDE
– Create project: Session2Ex– Create java class: Ex2WithWhile.java– Change the rule of games.– Exception input– Example debug project
RunRunSourceSource
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Arrays
int[] sourceArray = {2, 3, 1, 5, 10};
int[] targetArray = new int[sourceArray.length];
float[] f = new float[20];
Set data to array:
for (int i = 0; i < sourceArrays.length; i++)
targetArray[i] = sourceArray[i];
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Multidimensional ArraysDeclaring Variables of Multidimensional Arrays and Creating Multidimensional Arrays
int[][] matrix = new int[10][10]; orint matrix[][] = new int[10][10];matrix[0][0] = 3;
for (int i=0; i<matrix.length; i++) for (int j=0; j<matrix[i].length; j++) { matrix[i][j] = (int)(Math.random()*1000); }double[][] x;
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Multidimensional Array Illustration
0 1 2 3 4
0
7
0 1 2 3 4
1 2 3 4
0 1 2 3 4 matrix[2][1] = 7;
matrix = new int[5][5];
3
7
0 1 2
0 1 2
int[][] array = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9}, {10, 11, 12} };
1
2
3
4
5
6
8
9
10
11
12
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Declaring, Creating, and Initializing Using Shorthand Notations
You can also use a shorthand notation to declare, create and initialize a two-dimensional array. For example,
int[][] array = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9},
{10, 11, 12}
};
This is equivalent to the following statements: int[][] array = new int[4][3];
array[0][0] = 1; array[0][1] = 2; array[0][2] = 3;
array[1][0] = 4; array[1][1] = 5; array[1][2] = 6;
array[2][0] = 7; array[2][1] = 8; array[2][2] = 9;
array[3][0] = 10; array[3][1] = 11; array[3][2] = 12;
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Lengths of Multidimensional Arrays
int[][] array = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9}, {10, 11, 12}};array.lengtharray[0].lengtharray[1].lengtharray[2].length
Illustration on code
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Actions on Eclipse
Open Eclipse IDE– Create project: Session2Ex– Create java class: Ex2WithArray.java– Add String type– Change rule of games
RunRunSourceSource
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Action on EclipseExample 2.1
Adding and Multiplying Two Matrices
Objective: Use two-dimensional arrays to create two matrices, and then add and multiply the two matrices.
TestMatrixOperationTestMatrixOperation RunRun
55555454535352525151
45454444434342424141
35353434333332323131
25252424232322222121
15151414131312121111
5554535251
4544434241
3534333231
2524232221
1514131211
5554535251
4544434241
3534333231
2524232221
1514131211
bababababa
bababababa
bababababa
bababababa
bababababa
bbbbb
bbbbb
bbbbb
bbbbb
bbbbb
aaaaa
aaaaa
aaaaa
aaaaa
aaaaa
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Example 2.2 (cont) Adding and Multiplying Two Matrices
5554535251
4544434241
3534333231
2524232221
1514131211
5554535251
4544434241
3534333231
2524232221
1514131211
5554535251
4544434241
3534333231
2524232221
1514131211
ccccc
ccccc
ccccc
ccccc
ccccc
bbbbb
bbbbb
bbbbb
bbbbb
bbbbb
aaaaa
aaaaa
aaaaa
aaaaa
aaaaa
cij = ai1b1j+ai2b2j+ai3b3j+ai4b4j+ai5b5j
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Action on class
Teacher – [email protected]– 0984380003– https://play.google.com/store/search?q=thsoft+co&c=apps
Captions Members