java - Issue with getting text from a text field with .getText() -

i building application verifies logins amazon web service s3 file, can verify login fine, issue arises when try text entered user in textfield.

this section of code builds ui :

public class userinterface extends jframe implements actionlistener {  jlayeredpane pane; jframe f; jtextfield usernamelogin; jtextfield passwordlogin; userinterface ui; jbutton loginbutton; static string loggedinas = null; static amazons3       s3; static boolean trytologin = false;   public userinterface() {      jlayeredpane pane = new jlayeredpane();      jtextfield usernamelogin = new jtextfield("username...",20);     usernamelogin.setlocation(650,200);     usernamelogin.setsize(500, 30);     usernamelogin.setvisible(true);     pane.add(usernamelogin, 1, 0);      jtextfield passwordlogin = new jtextfield("password...",20);     passwordlogin.setlocation(650,240);     passwordlogin.setsize(500, 30);     passwordlogin.setvisible(true);     pane.add(passwordlogin, 1, 0);      jbutton loginbutton = new jbutton("login");     loginbutton.setlocation(650,290);     loginbutton.setsize(75, 20);     loginbutton.addactionlistener(this);     loginbutton.setvisible(true);     pane.add(loginbutton, 1, 0);       this.add(pane);  } 

i dont think problom comes there, wrong. next part of program logic processor works server verify login amazon s3. in main().

        int infinite = 1;     try {         system.out.println("downloading object");         s3object object = s3.getobject(new getobjectrequest("saucymmo", "logins.txt"));         system.out.println("content-type: "  + object.getobjectmetadata().getcontenttype());          while (infinite == 1) {             system.out.println("ran");             if (trytologin == true) {                 system.out.println("ran2");                 infinite = 0;              bufferedreader br = new bufferedreader(new inputstreamreader(object.getobjectcontent()));              string linevalue = null;              while((linevalue = br.readline()) != null && loggedinas == null){                  string splitresult[] = linevalue.split(",");                  boolean retval = splitresult[0].equals(ui.usernamelogin.gettext());                  boolean retval2 = splitresult[1].equals(ui.passwordlogin.gettext());                if (retval == true && retval2 == true) {                 loggedinas = splitresult[0];                 system.out.println("logged in : " + loggedinas);                }                else {                     system.out.println("split 0 : " + splitresult[0]);                     system.out.println("split 1 : " + splitresult[1]);                }              }              }         }     } catch (amazonserviceexception ase) {      } catch (amazonclientexception ace) {      } catch (ioexception e) {         e.printstacktrace();     }  

i null pointer exception when call "ui.usernamelogin.gettext()" or "ui.passwordlogin.gettext()".

specifically,

java.lang.nullpointerexception @ userinterface.main(userinterface.java:102) 

you defining local variable here in constructor

jtextfield usernamelogin = new jtextfield("username...",20);

that different jtextfield usernamelogin; declaration never initialized , null that's why have nullpointerexception.

change

public class userinterface extends jframe implements actionlistener {   jlayeredpane pane;   jframe f;   jtextfield usernamelogin;   jtextfield passwordlogin;   userinterface ui;   jbutton loginbutton;        public userinterface() {     layeredpane pane = new jlayeredpane();      jtextfield usernamelogin = new jtextfield("username...",20);     usernamelogin.setlocation(650,200);     usernamelogin.setsize(500, 30);     usernamelogin.setvisible(true);     pane.add(usernamelogin, 1, 0);      jtextfield passwordlogin = new jtextfield("password...",20);     passwordlogin.setlocation(650,240);     passwordlogin.setsize(500, 30);     passwordlogin.setvisible(true);     pane.add(passwordlogin, 1, 0);      jbutton loginbutton = new jbutton("login");     loginbutton.setlocation(650,290);     loginbutton.setsize(75, 20);     loginbutton.addactionlistener(this);     loginbutton.setvisible(true);     pane.add(loginbutton, 1, 0);       this.add(pane); } 

to

public class userinterface {     private jlayeredpane pane;     private jtextfield usernamelogin;     private jtextfield passwordlogin;     private jbutton loginbutton;      private jtextfield usernamelogin;      private jframe frame;      public userinterface() {     usernamelogin = new jtextfield("username...",20);     usernamelogin.setlocation(650,200);     usernamelogin.setsize(500, 30);     usernamelogin.setvisible(true);     pane.add(usernamelogin, 1, 0);      passwordlogin = new jtextfield("password...",20);     passwordlogin.setlocation(650,240);     passwordlogin.setsize(500, 30);     passwordlogin.setvisible(true);     pane.add(passwordlogin, 1, 0);      loginbutton = new jbutton("login");     loginbutton.setlocation(650,290);     loginbutton.setsize(75, 20);     loginbutton.addactionlistener(this);     loginbutton.setvisible(true);     pane.add(loginbutton, 1, 0);      frame= new jframe();     //configure jframe      frame.add(pane);     frame.pack();//size frame     frame.setvisible(boolean.true);     }        //you have added component       private class myactionlistener implements actionlistener{              @override              public void actionperformed(actionevent evt){                     //code here              }       }  } 

a few advices :

don't extends jframe have reference instead (composition on inheritance) , don't implement in top classes actionlistener instead use anonymous class or inner classes

some coding :

(retval == true && retval2 == true) change (retval && retval2)

manage exceptions , never blank catches

} catch (amazonserviceexception ase) {      }