operator
math
+, -, *, /
%(mod), ++(+1), –
auto add and substract
(++a) will do the operation first then expression
(a++) will do the expression first then operation
int a = 3;
int b = ++a;
// b = 4
int c = 3;
int d = --c;
// d = 2
relation operator
==, !=, >, >=
digit operator
apply on every digit of binary
A & B, A | B, A ^ B, ~A
A« 2: move digit to the left by argument
A = 0011 1100;
B = 0000 1101;
A&B = 0000 1100;
logical operator
A&&B, A||B, !A
assignment operator
A += B: A = A + B
…
condition operator
variable x = (expression) ? true-value: false-value;
instanceof
String name = 'James';
boolean result = name instanceof String;
// if name is String, true
loop structure
while
int x = 10;
while( x < 20 ) {
System.out.print("value of x : " + x );
x++;
System.out.print("\n");
}
do while
do{
System.out.print("value of x : " + x );
x++;
System.out.print("\n");
}while( x < 20 );
for
for(int x = 10; x < 20; x = x+1) {
System.out.print("value of x : " + x );
System.out.print("\n");
}
break keyword
for(int x : numbers ) {
if( x == 30 ) {
break;
}
continue keyword
for(int x : numbers ) {
if( x == 30 ) {
continue;
}
enhanced for
int [] numbers = {10, 20, 30, 40, 50};
for(int x : numbers ){
System.out.print( x );
System.out.print(",");
}
//
String [] names ={"James", "Larry", "Tom", "Lacy"};
for( String name : names ) {
System.out.print( name );
System.out.print(",");
}
branch statement
if
int x = 30;
if( x == 10 ){
System.out.print("Value of X is 10");
}else if( x == 20 ){
System.out.print("Value of X is 20");
}else if( x == 30 ){
System.out.print("Value of X is 30");
}else{
System.out.print("This is else ");
}
switch
the variable in switch can be byte, short, int or char
char grade = 'C';
switch(grade)
{
case 'A' :
System.out.println("excellent");
break;
case 'B' :
case 'C' :
System.out.println("good");
break;
case 'D' :
System.out.println("fair");
case 'F' :
System.out.println("keep working");
break;
default :
System.out.println("unknown");
}
System.out.println("your level is " + grade);
