一月二十八日 安卓开发七

在java类中 添加逻辑代码

package com.example.myapplication;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {


    private Button btn_query_count;
    private TextView tu_count;

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(@NonNull Message msg) {
            if (msg.what == 0) {
                int count=(Integer)msg.obj;
                tu_count.setText("数据库中的用户数量为："+count);
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {

        btn_query_count = findViewById(R.id.et2);
        tu_count = findViewById(R.id.et3);

        btn_query_count.setOnClickListener(this);

    }

    @Override
    public void onClick(View view) {

        if (view.getId() == R.id.et2) {
            doQueryCount();
        }

    }

    private void doQueryCount() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                int count = data.getUserSize();
                Message msg= Message.obtain();
                msg.what=0;
                msg.obj=count;
                //像主线程发送数据
                handler.sendMessage(msg);
            }
        }).start();
    }


}

 完成操作