How do you exit sub in Java

[xxarmoxx]

In vb you can say

if filename = "" then exit sub

and that will stop the function from executing more code, how can I do the same in java?

Here is what I got so far but its not compiling

    private void jToggleButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                               

 
        
        String filename=jTextArea1.getText();
        
        if filename = "" then return;
        
        
    }

What do i have to put instead of 'return'?