To update the UI in a child thread, use only handler

 Packagecom.pingyijinren.test;ImportAndroid.os.Handler;ImportAndroid.os.Message;Importandroid.support.v7.app.AppCompatActivity;ImportAndroid.os.Bundle;ImportAndroid.view.View;ImportAndroid.widget.Button;ImportAndroid.widget.TextView; Public classMainactivityextendsappcompatactivity{ Public Static Final intUpdate_text=1; PrivateTextView TextView; Privatebutton button; PrivateHandler handler=NewHandler () { Public voidhandlemessage (Message msg) {Switch(msg.what) { CaseUPDATE_TEXT:textView.setText ("HelloWorld");  Break; default:                   Break;    }      }    }; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); TextView=(TextView) Findviewbyid (R.id.textview); Button=(Button) Findviewbyid (R.id.button); Button.setonclicklistener (NewView.onclicklistener () {@Override Public voidOnClick (View v) {NewThread (NewRunnable () {@Override Public voidrun () {Message message=NewMessage (); Message.what=Update_text;                    Handler.sendmessage (message);            }}). Start ();    }        }); }}

To update the UI in a child thread, use only handler