Javase Basic Note Three

Four. Process Control

Branching structure:

1. Condition Judgment:

①IF (conditional expression) {}

②IF (conditional expression) {

//EXECUTE statement 1;

}else{

//EXECUTE statement 2;

}

③IF (conditional expression 1) {

//EXECUTE statement 1;

}else if (conditional expression 2) {

//EXECUTE statement 2;

}...

}else{

//EXECUTE statement;

}

Attention:

1. Once a conditional expression is met, the execution of the statement is executed, execution is completed, and the current condition is determined, and the following conditional structure statements are not executed.

2. If there is a "mutex" relationship between many conditional expressions, multiple structures can be swapped up and down in order

If there is a "containment" relationship between many conditional expressions, it is required that the scope of the conditional expression be small to be written on a large range.

2. Select structure

Switch (variable) {

Case value 1:

Case Value 2:

Break

...

Default

Break

}

Attention:

1. Variables can be of the following data types: byte short int Char enumeration String

2.case can only fill in the value of the variable, cannot write range

3.default; can be omitted, and its position is flexible, but usually placed after the case statement

4. Once a case statement is satisfied, enter to perform its operation until a break is encountered or the program terminates

5. In some cases, to determine if the condition of the statement satisfies the data type of the switch variable, and if the value is not many, it is recommended to select Swith-case, in addition, select If-else

Loop structure

1. Format:

① initialization conditions

② Cycle Conditions

③ Iteration Conditions

④ Loop Body

for (①;②;③) {

④

}

①

while (②) {

④

③

}

①

do{

④

③

}while (②);

Note: 1. Different loops can be converted to each other

The difference between 2.while and Do-while: The Do-while program executes at least once

2. Nested loops: Loops can also be declared in a looping structure. Let the inner Loop Structure Act as the loop body of the outer loop, if the outer loop executes MCI, the inner layer loops n times, and the whole program executes m*n times.

Topic:

for (int i = 0;i<3;i++) {

for (int j = 0;j<6;j++) {

System.out.print ("*");

}

System.out.println ();

}

Outer control number of rows, inner control number of columns

Example: 1.99 multiplication table 2. Prime numbers within 100 of output

3. Infinite loops

for (;;) {

...

if () {

Break

}

}

Or

while (ture)

...

if () {

Break

}

...

}

Often we provide a loop termination condition inside an infinite loop structure, using the break keyword. Otherwise, this loop will be executed indefinitely, resulting in a dead loop, which we want to avoid.

Break & Continue Keywords

Break

Used in swith-case structures or in cyclic structures

In the loop structure, once the break is executed, it jumps out of the current loop

Continue

Used in the loop structure

Once executed to continue, jump out of the loop

for (int i = 1;i <= 10;i++) {

if (i% 4 = = 0) {

Break 123

continue;//123567910

}

System.out.println (i);

}

In nested loops, a tagged break and continue are used.

lable:for (int i = 1;i < 5;i++) {

for (int j = 1;j <= 10;i++) {

if (i% 4 = = 0) {

Break able;

Continue lable;

}

System.out.println (j);

}

System.out.println ();

}

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Javase Basic Note Three