java-based day4

04.01_Java language basis (using the format and structure of the cycle and for an overview statement)

• A: Classification of the cyclic structure

  • for,while,do...while

• B: cyclic structure format for statement:

• for (initialization expression; conditional expression; expression after cyclic operation) {loop body;}

• C execution process:

  • a: perform the initialization statement

  • b: performing determination conditional statements, see the return value is true or false

    • If it is true, execution continues

    • If it is false, it is the end of the cycle

  • c: perform loop statement;

  • After the execution cycle operation expression: d

  • e: B back to continue.

• D: Case presentation

  • Output 10 "helloworld" in the console

04.02_Java Language Infrastructure (loop structure for the Exercise of the statement of acquiring data)

• A: Case presentation

  • Required: Please console output data 1-10

  • Required: Please output data 10-1 in the console

• B: Notes

  • a: to determine whether simple or complex conditional statement is the result of type boolean.

  • b: If the statement is a loop statement, the braces can be omitted; if multiple statements, the braces can be omitted. We recommend that you never omitted.

  • c: In general: There will be no opening brace semicolon, the semicolon there will be no opening brace

04.03_Java language basis (sum idea of ​​circular structure for the Exercise of the statement)

• A: Case presentation

  • Requirements: The data obtained between 1-10 and

• B: Students practice

  • Demand: find and even-numbered 1-100

  • Demand: find the odd and 1-100

04.04_Java language foundation (practice of daffodils loop structure for statement)

• A: Case presentation

  • Demand: the output of all the "narcissistic number" in the console

  • Called a three-digit number daffodils means that the digits of the cube and is equal to the number itself.

  • Example: 153 is a number daffodils.

  • 153 = 111 + 555 + 333 = 1 + 125 + 27 = 153

04.05_Java language basis (statistical idea of ​​circular structure for the Exercise of the statement)

• A: Case presentation

  • Requirements: Statistics, "the number of Narcissus" total number of

04.06_Java language foundation (basic format and structure while using a loop statement)

• Format A: cyclic structure while statement: The basic format of the while loop: while (judgment condition statement) {loop statement;}

  Full format: initialization statement; the while (judgment condition statement) {      loop statement;      controlling conditional statement; }
  
  
  
  
  
  

• B: execution process:

  • a: perform the initialization statement

  • b: performing determination conditional statements, see the return value is true or false

    • If it is true, execution continues

    • If it is false, it is the end of the cycle

  • c: perform loop statement;

  • d: execution control conditional statements

  • e: B back to continue.

• C: Case presentation

  • Required: Please console output data 1-10

04.07_Java language basis (exercise cycle structure while statement)

• A: sum thinking

  • Seeking 1-100 sum

• B: Statistical Thinking

  • Statistics "number of Narcissus" total number of

04.08_Java Language Infrastructure (looping structures do ... basic format and use while statements)

• A: looping structures do ... while statement format:

• loop do {statement;} while (judgment condition statement);

  
  Full format; 
  initialization statement; 
  do { 
      loop statement; 
      controlling conditional statement; 
  } the while (judgment condition statement);

• B: execution process:

  • a: perform the initialization statement

  • b: performing loop statement;

  • c: execution control conditional statements

  • d: judging the conditional statement execution, see the return value is true or false

    • If it is true, execution continues

    • If it is false, it is the end of the cycle

  • e: b back to continue.

• C: Case presentation

  • Required: Please console output data 1-10

04.09_Java language basis (difference between the loop structure three loop statements)

• A: Case presentation

  • Three loop difference statement:

  • do ... while loop executes loop body at least once.

  • And for, while loops must first determine whether the conditions established, and then decide whether to execute the loop body statement.

• B: Case presentation

  • for and while loops difference:

    • A: If you want to at the end of the cycle, continue to use that variable controlled conditions, using a while loop, or else use the for loop. I do not know who will use a for loop. Because the variable early disappeared from memory, you can improve memory usage efficiency.

04.10_Java language basis (infinite loop cycle considerations of structure)

• A: Be sure to pay attention to control problems that variable control of conditional statements, do not lose it, otherwise it is easy endless loop.

• B: The two most simple infinite loop format

  • while(true){...}

  • for(;;){...}

04.11_Java Language Infrastructure (cyclic structure nested loop output stars 4 rows and five columns)

• A: Case presentation

  • Required: Please outputs a 4 row 5 stars (*) in the pattern.

  • Figure: * * * *

    
    Note: 
        System.out.println ( "*"); and System.out.print ( "*"); the difference

• B: Conclusion:

  • An outer loop controlling the number of lines, number of columns within the control loop

04.12_Java Language Infrastructure (output loop nest cyclic structure equilateral triangle)

• A: Case presentation

• Required: Please output the following form * ** *** *

04.13_Java Language Infrastructure (cyclic structure multiplication table)

• A: Case presentation

  • Demand: the output of the multiplication table in the console.

• B: Code Optimization

• Note: '\ x' x denotes any, \ is the escape symbol, a practice known as transfer characters.

  
  '\ t' position of the tab key 
  '\ r' Enter 
  '\ n' new line 
  '\ "' 
  '\' '

04.14_Java language basis (control jump statements break statement)

• A: break usage scenarios

  • And the cycle can only switch

04.15_Java language basis (control jumps statement continue statement)

• A: continue usage scenarios

  • Only in the loop

04.16_Java language basis (control jumps statement label)

• Label: mark a cycle of its control

• Label composition rules: in fact valid identifier

• ​

  class Demo3_Mark {// mark marker

  
  static void main public (String [] args) {         / * Outer: for (int I =. 1; I <= 10; I ++) {// A numeral is, as long as the legal identifier to             System.out. the println ( "I =" + I);             Inner: for (int. 1 = J; J <= 10; J ++) {                 System.out.println ( "J =" + J);                 BREAK Outer;             }         *} /     System.out.println ( "Hello everybody");     http://www.heima.com     System.out.println ( "is really good"); }
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  }

04.17_Java language basis (control adjustment statement Exercise)

• A: Exercises

• for (int x = 1; x <= 10; x ++) {if (x% 3 == 0) {// Fill the code here} System.out.println ( "Java base classes");

  
  I want to output two times in the console: "Java foundation classes" 
  I want to output seven times in the console: "Java foundation classes" 
  I think 13 times the output in the console: "Java foundation classes"

04.18_Java language basis (control jumps statement return statement)

• A: The role of return

  • return

  • In fact, its role is not the end of the cycle, but the end of the method.

• B: Case presentation

  • The difference between the return and break and continue?

  • return is the end of the process

  • break is out of the loop

  • continue is to terminate this cycle continues for the next cycle

04.19_Java language base (method overview and formatting instructions)

• A: Why should Method

  • Improve the reusability of code

• B: What is the method

  • Completion of a particular function block.

• Method format: C

• Modifier return type method name (parameter type parameter name 1, parameter type parameter name 2 ...) {statements method body; return return value;}

• D: Method Format Description

  • Modifiers: Currently on the use of public static. We'll explain in detail later in other modifiers.

  • Return Value Type: Results of that data type.

  • Method name: conform to the naming rules. The convenience of our call.

  • parameter:

    • The actual parameters: that is actually involved in operations.

    • Formal parameters; the method is defined for receiving the actual parameter.

  • Parameter type: it is the data type of the parameter

  • Parameter name: variable name is

  • Method body statement: is the complete code for the function.

  • return: the end of the process.

  • Returns: is the result of the function, the return gives the caller.

04.20_Java language basis (summation of the case and its method call)

• A: How to write a method

  • 1, a clear return type

  • 2, clear the argument list

• B: Case presentation

  • Demand: Demand and the data of the two cases

• C: graphic method calls

04.21_Java language basis (Note Method)

• A: Method Invocation (specific return value)

  • a: a separate call, generally does not make sense, it is not recommended.

  • b: output calls, but not good enough. Because we may need further action on the results.

  • c: Assignment call recommendations.

• B: Case presentation

  • a: method does not call does not perform

  • b: same level method and the relationship is not nested definitions

  • c: the time between the method parameter defined, separated by commas

  • d: method is invoked in transmitting the data types do not

  • e: If the method has a clear return value must be a return value back

04.22_Java language basis (exercise method)

• A: Case presentation

  • Demand: two keyboard input data and returns the larger of two numbers

• B: Case presentation

  • Requirements: two keyboard input data, compare two numbers are equal

  • ​

    import java.util.Scanner;

    
    Test1_Method {class     public static void main (String [] args) {         Scanner Scanner new new SC = (the System.in); // Create Object keyboard input         System.out.println ( "Enter first integer:") ;         int x = sc.nextInt (); // x will be an integer in the keyboard input storage         System.out.println ( "Please enter the second integer:");         int sc.nextInt Y = (); // the keyboard input integer stored in y     // int max = getMax (X, y);     //System.out.println(max);     Boolean isEquals = B (X, y);     the System.out. the println (B); } / * return value greater even integers 1, return type int clear 2 clear parameter list int a, int b
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    * / 
    Public static int getMax (int a, int b) { 
        return A> B A:? B; 
    } / * determines two integers are equal 1, return type Boolean clear 2 clear parameter list int a, int b * / public static Boolean isEquals (A int, int B) {// if equal isEquals     return A == B; } }
    
    
    
    
    
    
    
    
    
    

    ​

04.23_Java language foundation (method of outputting a star and call)

• A: Case presentation

  • Requirements: keyboard entry of the number of rows and columns, a star in the console output

• B: Method Invocation :( no return value, void)

  • A separate call

  • Output call (error)

  • Assignment call (error)

04.24_Java language basis (exercise method)

• A: Case presentation

  • Demand: The keyboard input data corresponding to the output of the multiplication table

04.25_Java language base (method overloading overview and basic use)

• A: Overview of method overloading

  • Summing Case

    • 2 integer

    • 3 integer

    • 4 integer

• B: Method overloading:

  • In the same class, the same method name, a list of different parameters. It has nothing to do with the return value type.

  • A list of different parameters:

    • A: number of different parameters

    • B: Different types of parameters

    • C: sequence of the different parameters (operator overloading, but not in development)

04.26_Java language basis (whether comparative data method overload exercise equal)

• A: Case presentation

  • Requirements: Compare two data are equal.

  • Are two parameters of type int type, two double type, and tested in the main method

04.27_day04 summary

The summary of today's knowledge points again.