Does the android sub-thread really fail to update the ui? The android thread updates the ui.

Does the android sub-thread really fail to update the ui? The android thread updates the ui.

In actual development, the sub-thread cannot update the ui, but in the test code, we can update the ui in the sub-thread, for example: A textview performs findviewbyid in the oncreate lifecycle method.

Then, write a thread and perform settext on the textview directly in the thread. Then you will find that the miracle actually happened, And the ui was actually updated, and the app didn't actually get cresh, suddenly stunned

Then try to update the ui of the sub-thread in the onstart onresume method separately. You can update all the sub-threads, but note that, when the onresume life cycle method of our program is executed, an error will be reported when the ui is updated in the Child thread. For example, update the ui in a button click event, at this time, onresume must have been executed, and an error will be reported at this time. the reason is in the first oncreate onstart onresume life method. activity rootviewimpl has not been created yet. there is no problem in updating the ui at this time. however, after rootviewimpl is created, the ui cannot be updated in the Child thread. therefore, the method of updating the ui in the Child thread is completely unavailable in actual development. at the crucial moment, we should use the thread hanler method to update the ui.

The following is an example program:

Activity:

package com.example.testchildthreadgootheractivity;import android.app.Activity;import android.content.Context;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;public class MainActivity extends Activity {private Context context;private TextView tv_result;private Button btn_refresh;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);context = this;initVeiw();Log.e("test", "main thread,name:" + Thread.currentThread().getName()+ ",id:" + Thread.currentThread().getId());new Thread(new Runnable() {@Overridepublic void run() {Log.e("test", "child thread,name:" + Thread.currentThread().getName()+ ",id:" + Thread.currentThread().getId());tv_result.setText("oncreate refresh textview");}}).start();}@Overrideprotected void onStart() {super.onStart();new Thread(new Runnable() {@Overridepublic void run() {Log.e("test", "child thread,name:" + Thread.currentThread().getName()+ ",id:" + Thread.currentThread().getId());tv_result.setText("onstart refresh textview");}}).start();}@Overrideprotected void onResume() {super.onResume();new Thread(new Runnable() {@Overridepublic void run() {Log.e("test", "child thread,name:" + Thread.currentThread().getName()+ ",id:" + Thread.currentThread().getId());tv_result.setText("onresume refresh textview");}}).start();}private void initVeiw() {tv_result = (TextView) findViewById(R.id.tv_result);btn_refresh = (Button) findViewById(R.id.btn_refresh);btn_refresh.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {new Thread(new Runnable() {@Overridepublic void run() {Log.e("test", "child thread,name:" + Thread.currentThread().getName()+ ",id:" + Thread.currentThread().getId());tv_result.setText("onresume refresh textview");}}).start();}});}@Overrideprotected void onPause() {super.onPause();Log.e("test", "onPause");}@Overrideprotected void onStop() {super.onStop();Log.e("test", "onStop");}@Overrideprotected void onDestroy() {super.onDestroy();Log.e("test", "onDestroy");}@Overrideprotected void onRestart() {super.onRestart();Log.e("test", "onRestart");}}

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