我刚刚在java和mysql之间建立了连接。我只想实现sql语句。所以请帮助我如何才能做到这一点。下面是我的mysql连接代码。
数据库连接.java

package com.example.test;
import java.sql.*;
public class DB_Connect {
    Connection conn = null;
    public void DB_Connect() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/streamx", "root", "root");
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

这里我要实现sql语句。
登录.java

package com.example.test;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
import android.view.View;
import java.sql.*;

public class login extends AppCompatActivity {
    TextView signup;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        DB_Connect connect = new DB_Connect();
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        signup = (TextView)findViewById(R.id.signup);
        signup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openSignup();
            }
        });
    }
    public void openSignup(){
        Intent signup = new Intent(this, signup.class);
        startActivity(signup);
    }
}