Java Learning notes 03--judgment and looping statements

Structure of the program

In general, the structure of the program contains the following three kinds:

• Sequential structure

• Select structure

• Loop structure

When you use switch to make an expression, you can use only numbers or characters in an expression.

PublicClassT{To complete a arithmetic functionPublicStaticvoidMain(StringArgs[]){IntX=3;IntY=6;CharOper=+;Switch(Oper){Case+:{Perform an addition operationSystem.Out.println("x + y ="+(X+Y));Break;}Case‘-‘:{Perform a subtraction operationSystem.Out.println("X-y ="+(X-Y));Break;}Case‘*‘:{Perform multiplication operationsSystem.Out.println("x * y ="+(X*Y));Break;}Case '/' :{//perform division operation system.out. ( "x/y =" +  (x /y break } default:{system. Out. ( "Unknown operation! ") break } } } }        /span>                

In the above operation, there will be a break after each statement, which means exiting the entire switch () statement,

If this statement is not written, all operations will be output after the first satisfy the condition until a break is encountered

PublicClassT{To complete a arithmetic functionPublicStaticvoidMain(StringArgs[]){IntX=1int sum = 0 //Save cumulative results while (x<= 10sum += x //to accumulate operations x++ //Modify loop condition } system.. ( "1--and 10 cumulative result:" + sum ) } }             /span>                

PublicClassT{PublicStaticvoidMain(StringArgs[]){IntX=1;int sum = 0 //Save cumulative results do{sum += x //perform the cumulative operation x++ }while (x<= 10 system.. ( "1--and 10 cumulative result:" + sum ) } }             /span>                

PublicClassT{PublicStaticvoidMain(StringArgs[]){int sum = 0 //Save cumulative results for (int x =1; X<=10; X++) {sum += x } system.. ( "1--and 10 cumulative result:" + sum ) } }             /span>                

Interrupt statement

PublicClassT{PublicStaticvoidMain(Stringargs[]) { for(int i=0;  I<ten;  I+ +) { If(i= =3) {break ; } System.  Out.  println("i =" + i) ; } } }< /c21> 

Output results

i = 0  i = 1  

Using continue is to interrupt the execution of one cycle

PublicClassT{PublicStaticvoidMain(Stringargs[]) { for(int i=0;  I<ten;  I+ +) { If(i= =3) { continue; } System.  Out.  println("i =" + i) ; } } }< /c21> 

Output results

i = 0  i = 1  i = 2  i = 4  i = 5  i = 6  i = 7  i = 8  i = 9

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Java Learning notes 03--judgment and looping statements