Statements are complete units of execution in a Java application, and to use the same analogy as the Oracle documentation, they resemble sentences in natural languages.
Statements can be grouped in blocks of zero or more statements inside braces ({ … }), as we’ve seen in the examples of method declarations in Chapter 1. We’ll be using more examples of blocks of code in the next sections related to Control Flow statements.
Types of Statements
Declaration Statements
We’ve used them multiple times before and are the statements we use to declare a variable, for example:
int number;
Door door;As mentioned in a previous section, we can mix a declaration and an assignment statement in a single line for simplicity, for example, we could do the following:
int number = 1;Expression Statements
As mentioned in the previous section, different types of expressions can be converted into statements by adding a semi-colon at the end, for example:
// object creation statement
door = new Door();
// method invocation statements
door.lockDoor();
System.out.println("Is door locked? " + door.locked);
// assignment statement
number = 1;
// decrement statement
number--;
// increment statement
number++;Control Flow Statements
In general, the statements will be executed in the order they are written in the Java code. However, there will be occasions where we need to decide whether a certain block of code needs to be executed or not, or where we need to repeat a block of code several times.
Control flow statements allow us to do this and will be covered in the following sections.
| So far in this course, we haven’t used control flow statements. |