android 定时5S更新一次UI，服务器

package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
public class MainActivity extends AppCompatActivity {
    TextView tv;
    Button ks;
    Timer timer = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = (TextView) findViewById(R.id.tv);
        ks = (Button) findViewById(R.id.bt);
        if (null == timer) {
            timer = new Timer();
        }
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                OkHttpClient client = new OkHttpClient();
                Request request = new Request.Builder()
                        .get()
                        .url("http://www.baidu.com")
                        .build();
                Call call = client.newCall(request);
                call.enqueue(new Callback() {
                    @Override
                    public void onFailure(Call call, IOException e) {
                        Toast.makeText(MainActivity.this, "get failed", Toast.LENGTH_SHORT).show();
                    }
                    @Override
                    public void onResponse(Call call, final Response response) throws IOException {
                        final String res = response.body().string();
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                tv.setText(res);
                            }
                        });
                    }
                });
                Log.e("ttt", "ttt");
            }
        }, 5 * 1000, 5 * 1000);
    }
}