JAVA基礎之表達式,語句,和塊
表達式(expression)
- 表達式是遵循java語法的基礎上,由變量(variable),運算符(operators),方法調用(method invocations)並返回單個值的組合 eg:
int cadence = 0; //int cadence = 0
anArray[0] = 100; // anArray[0] = 100
System.out.println("Element 1 at index 0: " + anArray[0]);
int result = 1 + 2; // result is now 3
if (value1 == value2)
System.out.println("value1 == value2");
- 複合表達式(compound expression)
1 * 2 * 3
- 運算符的優先級
提倡清楚明確的括號
x + y / 100; //ambiguous
x + (y / 100) // unambiguous, recommended
Statements(語句)
- 賦值語句(Assignment expressions)
- 自增自減語句(Inrement statements ,any use of ++ or –)
- 方法執行語句(Method invocation)
- 對象創建語句(object creation expression)
- 聲明語句(declaration statements)
- 控制語句(control flow statemets)
// assignment statement
aValue = 8933.234;
// increment statement
aValue++;
// method invocation statement
System.out.println("Hello World!");
// object creation statement
Bicycle myBike = new Bicycle();
blocks (塊)
即大括號包含的語句
class BlockDemo {
public static void main(String[] args) {
boolean condition = true;
if (condition) { // begin block 1
System.out.println("Condition is true.");
} // end block one
else { // begin block 2
System.out.println("Condition is false.");
} // end block 2
}
}
靜態代碼塊的使用