programming java basics picture question?

Question

when compiling, im getting the error "cannot find symbol - constructor Picture(java.lang.String)"

public class Picture
{
public void show()
{
String fileName;
fileName = FileChooser.pickAFile();

Picture picture1;
picture1 = new Picture();
picture1.show();

Picture picture2;
picture2 = new Picture(fileName);
picture2.show();
}
}

Answer 1

This is a problem with your Picture class. You are creating 2 variables called picture1 and picture2. When you instantiate the second variable (picture2) you are passing a string into the constructor. The picture class you are showing us only has a show() public method and no constructor that takes a String.



To fix this you will need to do 1 of 2 things:

1. Remove the filename from the constructor when you instantiate the Picture class. Example: Picture picture2 = new Picture();



2. Add a constructor to the class that will accept a String but you will need to move your FileChooser step into this constructor and make the fileName string global within the class.



Hope this helps.

Answer 2

Basically your class does not have constructor(s). A constructor is a method that allocate memory and build the class instance.



The ways you called your class

1. picture1 = new Picture();

2. picture2 = new Picture(fileName);

require 2 constructors. However, Java compiler is able to generate "default constructor" is none is give. So for #1 -- Java generates it.



But the compiler does not know how to create constructor for #2 since it has to accept a parameter. Here you have to create this constructor yourself.

Answer 3

The JVM is complaining because of the constructor. The class does not define a constructor in your code so the JVM makes a default constructor. Your code is like this to the Java Runtime:



public class Picture {



public Picture() {

// this is the default constructor

// either loads some vars

// or call a method

}



public Picture( String fname ) {

// here is your custom constructor

// and this is polymorphism at work

// you have two constructors, java

// looks for the constructor that will "fit"

String fileName = fname;

File file = new File( fileName );

}



// then some methods

private void method1() {

// do something

}



} // end of class



To make this a standalone, executable class, you need a main method. So, you have a few more things to consider for what you are trying to do.

Answer 4

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