Methods
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Methods in Java
Methods • A method is a piece of java code that does a job • Defined within the curly brackets of a class definition • Two types – 1. Static methods (also called class methods) do a job for a programmer – 2. Instance methods manipulate the data within a class – For now we will talk about static methods
• Methods are sometimes called functions
The parts of a method 1. Visibility • •
2. 3. 4. 5.
Public - any part of the Java program can use it Private - can only be used within the same class
Type of method (static?) Return type (what type of information it returns) Name Parameters - Data given to the method to do its job. 6. Body - The statements that get executed when the method is called.
Parts of a Method 1. Visibility
2. Static3. Return type (void means nothing returned) 4. Method name
public static void main (String[] args) { System.out.print(“Hello world”); }
5. List of parameters 6. Body inside curly brackets
Indenting Methods and Functions • Statements inside the method or function must be indented • Close bracket at end should be indented the same as the definition • Open bracket can be on same line or next line
void myMethod(){ statement1 }
Running a Java method • The body of a method between the curly brackets contain one or more statements • Statements are separated from one another by semicolons • When a method is run, it executes the statements one at a time • When Java is run, it looks for a method called main and runs it • The main method can call other methods, either in the same class or in other classes.
Calling a Java method To call a method, use the class name followed by a . followed by the method name class theClass { public static void main(String[] args) { theClass.theMethod(); } public static void theMethod() { System.out.print(“hello”); } }
In the example, the main method calls on theMethod What does this program print?
Some common statements • System.out.println(“something to print”); – System.out.println prints whatever is inside the parentheses to the console – Moves the console cursor to a new line when it is done.
• System.out.print(“something else”); – Similar to System.out.println, but does not move the cursor to a new line.
Summary • Two kinds of methods – Static methods do work for the programmer – Instance methods manipulate data (we won’t talk about these)
• Method definitions have multiple parts. • The body of a method contains one or more statements. – End with a semicolon – Are executed in order when the method is run
• The main method is run when a Java program starts • System.out.print/println send output to the console
Methods • A method is a piece of java code that does a job • Defined within the curly brackets of a class definition • Two types – 1. Static methods (also called class methods) do a job for a programmer – 2. Instance methods manipulate the data within a class – For now we will talk about static methods
• Methods are sometimes called functions
The parts of a method 1. Visibility • •
2. 3. 4. 5.
Public - any part of the Java program can use it Private - can only be used within the same class
Type of method (static?) Return type (what type of information it returns) Name Parameters - Data given to the method to do its job. 6. Body - The statements that get executed when the method is called.
Parts of a Method 1. Visibility
2. Static3. Return type (void means nothing returned) 4. Method name
public static void main (String[] args) { System.out.print(“Hello world”); }
5. List of parameters 6. Body inside curly brackets
Indenting Methods and Functions • Statements inside the method or function must be indented • Close bracket at end should be indented the same as the definition • Open bracket can be on same line or next line
void myMethod(){ statement1 }
Running a Java method • The body of a method between the curly brackets contain one or more statements • Statements are separated from one another by semicolons • When a method is run, it executes the statements one at a time • When Java is run, it looks for a method called main and runs it • The main method can call other methods, either in the same class or in other classes.
Calling a Java method To call a method, use the class name followed by a . followed by the method name class theClass { public static void main(String[] args) { theClass.theMethod(); } public static void theMethod() { System.out.print(“hello”); } }
In the example, the main method calls on theMethod What does this program print?
Some common statements • System.out.println(“something to print”); – System.out.println prints whatever is inside the parentheses to the console – Moves the console cursor to a new line when it is done.
• System.out.print(“something else”); – Similar to System.out.println, but does not move the cursor to a new line.
Summary • Two kinds of methods – Static methods do work for the programmer – Instance methods manipulate data (we won’t talk about these)
• Method definitions have multiple parts. • The body of a method contains one or more statements. – End with a semicolon – Are executed in order when the method is run
• The main method is run when a Java program starts • System.out.print/println send output to the console
