java - boolean method canPaste() does not return false even when the condition is satisfied -


when string cpbtxt null, method should return false not return anything.please help. there no errors. i've tried "cpbtxt.equals()" still no luck. please tell me going wrong? here complete code:

import java.util.*; import java.io.*; import java.awt.*; import java.awt.event.*; import java.awt.datatransfer.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.undo.*; import javax.swing.text.*;  class sample extends jframe implements menulistener { jmenubar mb; jmenu em; jmenuitem paste; jtextarea t; public sample() {     setlayout(new borderlayout());     setsize(400,400);     setdefaultcloseoperation(exit_on_close);      mb = new jmenubar();     em = new jmenu("edit");     paste = new jmenuitem("paste");      add(mb,borderlayout.north);     mb.add(em);     em.add(paste);     em.addmenulistener(this);      t = new jtextarea();     add(t,borderlayout.center); }  public boolean canpaste() throws exception {     clipboard cpb = toolkit.getdefaulttoolkit().getsystemclipboard();     string cpbtxt = (string)cpb.getdata(dataflavor.stringflavor);     if(cpbtxt == null)         return false;     else         return true; }  public void menuselected(menuevent me) {     if(me.getsource() == em)     {         try {         paste.setenabled(canpaste());         } catch(exception e) { system.out.println(e); }     } } public void menudeselected(menuevent me)   {   } public void menucanceled(menuevent me)   {   } }  class samplemain { public static void main(string[]args)    {     sample s1 = new sample();     s1.setvisible(true);    } }

change menuselected method this:

public void menuselected(menuevent me) {     if(me.getsource() == em) {         boolean canpasteresult = false;         try {             canpasteresult = canpaste();         } catch(exception e) { system.out.println(e); }         paste.setenabled(canpasteresult);     } }

with code method didn't change enabled state of menuitem if canpaste method throwed exception example if have selected file in clipboard.
code situation result in disabled state.


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