CODEWITHSUNDEEP
javainstance
Stefan
Stefan

Reputation: 1

How do I make an instance of a class availabile in different methods?

I have created an instance of the class DownloadManager in a method (private void jButton2ActionPerformed) and need to access it in another method?

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
    //need to access the instance dman here
}                                        

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    DownloadManager dman = new DownloadManager();
    dman.actionAdd("http://dev.x-plane.com/download/tools/wed_mac_141r1.zip");
    dman.actionAdd("http://dev.x-plane.com/download/tools/wed_mac_141r1.zip");
    dman.setVisible(true); 
}

Upvotes: 0

Views: 39

Answers (1)

Sweeper
Sweeper

Reputation: 272370

"If you want to be able to access a variable from two different methods, define the variable in the enclosing scope of the method." -Sweeper

Which basically means you should "drag" the variable outside of the methods:

DownloadManager dman = new DownloadManager(); //Should put the variable here!
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
    //need to access the instance dman here
}                                        

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    //DownloadManager dman = new DownloadManager(); I moved this line to above!
    dman.actionAdd("http://dev.x-plane.com/download/tools/wed_mac_141r1.zip");
    dman.actionAdd("http://dev.x-plane.com/download/tools/wed_mac_141r1.zip");
    dman.setVisible(true); 
}

That's very simple isn't it?

Alternatively, you can create a class for getting the download manager:

public final class DownloadManagerUtility {
    private DownloadManagerUtility () { // private constructor so that people don't accidentally instantiate this

    }

    private DownloadManager dman = new DownloadManager();
    public static void getDownloadManager() { return dman; }
}

The advantage of this is that you can add more methods that are related to download manager in a separate class, which increases maintainability.

Upvotes: 1

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