Android activity does not run. Here's the code -
while try start activity, not run.
logcat shows following error :
07-25 12:10:46.813: e/androidruntime(797): fatal exception: main 07-25 12:10:46.813: e/androidruntime(797): java.lang.runtimeexception: unable instantiate activity componentinfo{com.example.testingandroid/com.example.testingandroid.dosums}: java.lang.nullpointerexception
my code :
public class dosums extends activity implements onclicklistener { public radiobutton r1 = (radiobutton) findviewbyid(r.id.doradiobutton1); public radiobutton r2 = (radiobutton) findviewbyid(r.id.doradiobutton2); public radiobutton r3 = (radiobutton) findviewbyid(r.id.doradiobutton3); public radiobutton r4 = (radiobutton) findviewbyid(r.id.doradiobutton4); public edittext et = (edittext) findviewbyid(r.id.doedittext1); //button btnnextscreen = (button) findviewbyid(r.id.button1); timeanddistancem pen = new timeanddistancem(); public string q, a, finalvalue, scale; public double fv; @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_do_sums); objcreator(); //btnnextscreen.setonclicklistener(this); r1.setonclicklistener(this); r2.setonclicklistener(this); r3.setonclicklistener(this); r4.setonclicklistener(this); } @override public boolean oncreateoptionsmenu(menu menu) { // inflate menu; adds items action bar if present. getmenuinflater().inflate(r.menu.do_sums, menu); return true; } public void objcreator() { pen.timeanddistancem(); // setting question string q = pen.q; et.settext("question" + q); // setting options // 1. getting options options ops = new options(); ops.optionscreator(pen.fv, pen.scale); // 2.assigning options r1.settext(ops.jradiobutton1); r2.settext(ops.jradiobutton2); r3.settext(ops.jradiobutton3); r4.settext(ops.jradiobutton4); } public void radiobuttonaction(radiobutton testradio) { if (testradio.gettext().tostring().equals(pen.finalvalue)) { objcreator(); } } @override public void onclick(view arg0) { switch (arg0.getid()) { /*case r.id.doradiobutton1: pen.timeanddistancem(); string q = pen.q; et.settext("question" + q); break;*/ case r.id.doradiobutton1: radiobuttonaction(r1); break; case r.id.doradiobutton2: radiobuttonaction(r2); break; case r.id.doradiobutton3: radiobuttonaction(r3); break; case r.id.doradiobutton4: radiobuttonaction(r4); break; } } }
you should find views after setting content view activity
:
public radiobutton r1; public radiobutton r2; public radiobutton r3; public radiobutton r4; public edittext et; protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_do_sums); //here should retreive views ids r1 = (radiobutton) findviewbyid(r.id.doradiobutton1); r2 = (radiobutton) findviewbyid(r.id.doradiobutton2); r3 = (radiobutton) findviewbyid(r.id.doradiobutton3); r4 = (radiobutton) findviewbyid(r.id.doradiobutton4); et = (edittext) findviewbyid(r.id.doedittext1);
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