Classes and Objects - Beginning Java 8 Fundamentals - page 254

Table 6-6. Examples of Classes for Which a Default Constructor Is Added by the Java Compiler

Source Code for Your Class Compiled Version of Your Class Comments

public class Test {
}

public class Test {
public Test() {
}
}

The compiler adds a default constructor with
public access level.

class Test {
}

class Test {
Test() {
}
}

The compiler adds a default construct with
package-level access.

public class Test {
Test() {
}
}

public class Test {
Test() {
}
}

The Test class already had a constructor. The
compiler does not add any constructor.

public class Test {
public Test(int x) {
}
}

public class Test {
public Test(int x) {
}
}

The Test class already had a constructor. The
compiler does not add any constructor.

public class Test {
private class Inner {
}
}

public class Test {
public Test() {
}
private class Inner {
private Inner(){
}
}
}

Test is a public top-level class and Inner is
a private inner class. The compiler adds a
public default constructor for the Test class
and a private default constructor for the
Inner class.

■ It is good programming practice to add a constructor explicitly to all your classes rather than letting the compiler
add a default constructor for your classes. the story of constructors is not over yet. You will revisit constructors in the
chapter on inheritance.

Tip

A static Constructor
Constructors are used in the context of the creating a new object; hence, it is consider part of the object context, not
the class context. You cannot declare a constructor static . The keyword this , which is a reference to the current
object, is available inside the body of a constructor as it is available inside the body of an instance method.