Meet_you/MainActivity.java

package com.example.meetyou;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);//xml文件和java文件一一对应9,
        Button button1 = (Button)findViewById(R.id.register);
        button1.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view)
            {
                Intent intent = new Intent(MainActivity.this,register.class);
                startActivity(intent);
            }
        });
        Button button2 = (Button)findViewById(R.id.login);
        button2.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view)
            {
                Intent intent = new Intent(MainActivity.this,login.class);
                startActivity(intent);
            }
        });
    }
}