I extended the class called Frotz, and the compiler is giving me an error message “No constructor Frotz()” in the child class. Why?
When you define a constructor for a class, the compiler inserts a call to the superclass’ parameterless constructor unless you explicitly call the superclass’ constructor at the start of your constructor. If the superclass doesn’t *have* a parameterless constructor, the compiler emits a message to that effect. The solution is usually to call the superclass’ constructor at the start of your constructor.
• A. When you define a constructor for a class, unless you explicitly call the superclass’ constructor at the start, a call to the superclass’ parameterless constructor is implicitly inserted. The problem you’re seeing is what happens when the superclass doesn’t *have* a parameterless constructor. The solution is usually to call the correct version of the superclass’ constructor with the right parameters.
When you define a constructor for a class, the compiler inserts a call to the superclass’ parameterless constructor unless you explicitly call the superclass’ constructor at the start of your constructor, or you call another constructor in the same class with this(). So if the superclass doesn’t *have* a parameterless constructor, the compiler emits a message to that effect. The solution is usually to call the superclass’ constructor at the start of your constructor. • (Sect. 5) No constructor matching MyCheckbox(myApplet) MyApplet.java:11: No constructor matching MyCheckbox(myApplet) found in class MyCheckbox. bp1 = new MyCheckbox(this); ^ If a compiler isn’t finding a constructor you thought you created, check whether you gave a return value to the method (remember, constructors have no return value). E.g., public void MyCheckbox( Container parent ) If you did, the compiler will think it is an ordinary method, not a constructor. This is a common mistake and hard to spot. • (Sect. 5)
When you define a constructor for a class, the compiler inserts a call to the superclass’ parameterless constructor unless you explicitly call the superclass’ constructor at the start of your constructor. If the superclass doesn’t *have* a parameterless constructor, the compiler emits a message to that effect. The solution is usually to call the superclass’ constructor at the start of your constructor. • (Sect. 5) No constructor matching MyCheckbox(myApplet) MyApplet.java:11: No constructor matching MyCheckbox(myApplet) found in class MyCheckbox. bp1 = new MyCheckbox(this); ^ If a compiler isn’t finding a constructor you thought you created, check whether you gave a return value to the method (remember, constructors have no return value). E.g., public void MyCheckbox( Container parent ) If you did, the compiler will think it is an ordinary method, not a constructor. This is a common mistake and hard to spot. • (Sect. 5) Type expected {public method variable} public static void main(Str
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