Question

i designed java desktop application
in that application when i press a button
another Jframe is shown that draws a tree
but when i close the Jframe whole operation is close
but i only want to close that Jfarme what should i do?
here is the jframe codes:

public  class DrawTree extends JFrame{
 public int XDIM, YDIM;
public Graphics display;

@Override
public void paint(Graphics g) {} // override method

// constructor sets window dimensions
public DrawTree(int x, int y)
{
XDIM = x;  YDIM = y;
this.setBounds(0,0,XDIM,YDIM);
this.setVisible(false); 
    this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
display = this.getGraphics();
// draw static background as a black rectangle
display.setColor(Color.black);
display.fillRect(0,0,x,y);
    display.setColor(Color.red);
try{Thread.sleep(500);} catch(Exception e) {} // Synch with system
}  // drawingwindow


public static int depth(BinaryNode N)  // find max depth of tree
{
if (N==null) return 0;
    int l = depth(N.left);
    int r = depth(N.right);
    if (l>r) return l+1; else return r+1;
}

// internal vars used by drawtree routines:
private int bheight = 50; // branch height
private int yoff = 30;  // static y-offset

// l is level, lb,rb are the bounds (position of left and right child)
private void drawnode(BinaryNode N,int l, int lb, int rb)
{
if (N==null) return;
try{Thread.sleep(100);} catch(Exception e) {} // slow down
    display.setColor(Color.green);
display.fillOval(((lb+rb)/2)-10,yoff+(l*bheight),20,20);
display.setColor(Color.red);
display.drawString(N.element+"",((lb+rb)/2)-5,yoff+15+(l*bheight));
display.setColor(Color.blue); // draw branches
    if (N.left!=null)
    {
       display.drawLine((lb+rb)/2,yoff+10+(l*bheight),((3*lb+rb)/4),yoff+(l*bheight+bheight));
           drawnode(N.left,l+1,lb,(lb+rb)/2);
    }
    if (N.right!=null)
    {
           display.drawLine((lb+rb)/2,yoff+10+(l*bheight),((3*rb+lb)/4),yoff+(l*bheight+bheight));
           drawnode(N.right,l+1,(lb+rb)/2,rb);
    }
} // drawnode

public void drawtree(BinaryNode T)
{
    if (T==null) return;
int d = depth(T);
bheight = (YDIM/d);
display.setColor(Color.white);
display.fillRect(0,0,XDIM,YDIM);  // clear background
    drawnode(T,0,0,XDIM);
}}

and another question

when i new a object from my tree class,i want to access that object in all my button codes
so where i should define that or better to say , how i should define that object that can access in all my codes??

Answer 1

You can simply hide the JFrame.

this.hide();

Edit: For the above: Youssef G’s answer is better.

For the 2nd part of the question. Create your tree class and pass the object around in your program so it is the same tree object. Don’t create a new one.

For example:

Class A {
     B b;    //B object inside class A
     Tree t;  //Tree object inside class A
}
Class B {
     Tree t;    //Tree object inside class B
}

Now you have a tree object in both classes. You can create a new tree which is class b’s tree while code is running in Class A. Then say this.t = b.t;

Hope this helps.