Error at this.this$0

Hi I need help in this code. The code is not mine, I am just trying to understand the logic of it but I'm already out of ideas on how to solve this problem. Please help. Thank you . This is the code:

this.this$0.excel = this.this$0.fc.getSelectedFile();
this.this$0.sheets.setText("");
this.this$0.sheets.setText("Selected script: " + this.this$0.excel.getName() + 
  "");