Check out example codes for "create jframe java". It will help you in understanding the concepts better.

Code Example 1

public JFrame frame = new JFrame();//creating jframe

Class main(){
public static void main(String[] args){
  frame.setSize(200,200); //setting size
  frame.setVisable(true); //sets visability 
  frame.setDefaultCloseOperation.(JFrame.EXIT_ON_CLOSE); //allow jframe to close when clicked

}
  }

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