About some loops in Java

1:switch Statements
(1) format:
switch (expression) {
Case value 1:
statement body 1;
Break ;
Case value 2:
Statement body 2;
Break ;
...
Default:
statement body n+1;
Break ;
}

Description of format explanation:
switch: Indicates that this is a switch statement.
expression: can be Byte,short,int,char
JDK5 can be enumerated later
JDK7 can be a string later
Case : The value that follows is the value to compare to the expression
break: Indicates that the program is interrupted here, jumping out of the switch statement
Default: If all cases do not match, execute here, equivalent to the else in the IF statement
(2) face test
can a switch statement be an expression of byte ? Can it be a long? Can it be a string?
Yes , no, JDK7 can be later.
(3) execution process:
A: Calculate the value of an expression first
B: Match each case, and if there is one, execute the corresponding statement body and see the break end.
C: If there is no match, execute the default statement body n+1.
(4) Precautions:
A:case can only be constants, cannot be variables, and values after multiple case cannot appear the same
can b:default be omitted ?
it can be omitted, but it is not recommended, because it is used to prompt for incorrect conditions.
Special Cases:
Case , you can fix the value.
a,b,c,d
can c:break be omitted ?
can be omitted, but the result may not be what we want.
There is a phenomenon: case penetrating.
The final recommendation is not to omit
D:default must be at the end?
No, it can be anywhere. But the suggestion at the end.
the end condition of the E:switch statement
A: It's over when you hit the break.
B: Execution ends at the end.

(6) If statement and switch statement respective scene
A:If
for Boolean-type judgments
for a range of judgments
Judging for a few constants
B:switch
Judging for a few constants

2: Loop statement
(1) There are three kinds: for,while,do...while
(2) for Loop statement
A: Format
For (initialize statement; Judge conditional statement; Control condition statement) {
loop body statement;
}

Execution Process:
A: Execute initialization statement
B: Execute judgment condition statement
If this is true, continue
If this is false, the loop will end.
C: Execute loop body Statement
d: Execute control condition Statement
e: Back to B
B: precautions
A: Judging conditional statements whether simple or complex, the result is a Boolean type
B: Loop body statement If it is one, you can omit the curly brace, but it is not recommended
C: There is a semicolon there is no left curly brace, there is no semicolon on the left curly brace

Case:
g: Number of daffodils printed on the console

(3) while loop
A: Basic Format
While (judging condition statement) {
loop body statement;
}

Extended Format:
initialization statements;
While (judging condition statement) {
loop body statement;
control condition statement;
}
B:while's Practice
use while to improve the For statement practice
the difference between c:for and while
A: The difference in use
The control condition variable for the For statement cannot be used at the end of the loop.
while the while can continue to be used.
B: The difference in understanding
for a range of judgments
the while is suitable for ambiguous times
(4) Do...while cycle
A: Basic Format
Do {
loop body statement;
}while (Judgment condition statement);

Extended Format:
initialization statements;
Do {
loop body statement;
control condition statement;
}while (Judgment condition statement);

by looking at the format, we can see that in fact, the format of the three loops can be unified.
B: The difference between three cycles
A:do...while Loop performs at least one loop body
The b:for and while must first determine if the condition is true before deciding whether to execute the loop body
(5) Precautions for circular use (dead cycle)
A: Must pay attention to modify the control conditions, otherwise prone to die cycle.
B: The simplest form of dead loop
A:while (True) {...}

b:for (;;) {}

3: Control jump Statement
(1) Break: Meaning of the Interruption
A: It is meaningless to leave this scenario in the loop and switch statements.
B: Role
A: Jump out of single-layer loops
B: Jump out of multi-layer loop, need the match of label statement
(2) Continue: Continue
A: It is meaningless to leave this scenario in the loop.
B: Role
A: Jump out of the single-layer loop once, you can continue the next time
C: Blank question
for (int x=1; x<=10; x + +) {
if (x%3 = = 0) {
//Code completion
}
System.out.println ("Java Basic class");
}
How to make the console output 2 times: Java Basic class
How to make the console output 7 times: Java Basic class
How to make the console output 13 times: Java Basic class
(3) return: Back
A: Used to end the method, the following will continue to explain and use.
B: Once a return has been encountered, the program will not continue to execute in the future.

About some loops in Java