package com.example.lenovo.myapplication;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
EditText E1,E2;
syq my;
SQLiteDatabase mydb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
E1=findViewById(R.id.e1);
E2=findViewById(R.id.e2);
}
public void dl(View view) {
String name=E1.getText().toString();
String pwd=E2.getText().toString();
my=new syq (MainActivity.this,"userdb.db",null,1);
mydb=my.getWritableDatabase();
Cursor c=mydb.query("users",new String[]{"userid"},"userid=? and password=?",new String[]{name,pwd},null,null,null);//1111111111111111
if (c.moveToFirst()){
startActivity(new Intent(MainActivity.this,Main2Activity.class));
}
else{
Toast.makeText(MainActivity.this,"登录失败！",Toast.LENGTH_LONG).show();
}
}
public void zc(View view) {
String name=E1.getText().toString();
String pwd=E2.getText().toString();
my=new syq(MainActivity.this,"userdb.db",null,1);
mydb=my.getWritableDatabase();
ContentValues CV=new ContentValues();
CV.put("userid",name);
CV.put("password",pwd);
mydb.insert("users",null,CV);
Toast.makeText(MainActivity.this,"注册完成！",Toast.LENGTH_LONG).show();
}
}

楼主牛逼

package com.example.lenovo.myapplication;
import android.app.AppComponentFactory;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class syq extends SQLiteOpenHelper {
private static String a="create table users(id integer primary key autoincrement,userid text,password text)";
public syq( Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(a);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}

11111

java1
package com.example.lenovo.myapplication;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
EditText E1,E2;
MySqlite my;
SQLiteDatabase mydb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
E1=findViewById(R.id.e1);
E2=findViewById(R.id.e2);
}
public void dl(View view) {
String name=E1.getText().toString();
String pwd=E2.getText().toString();
my=new MySqlite(MainActivity.this,"userdb.db",null,1);
mydb=my.getWritableDatabase();
Cursor c=mydb.query("users",new String[]{"userid"},"userid=? and password=?",new String[]{name,pwd},null,null,null);
if (c.moveToFirst()){
startActivity(new Intent(MainActivity.this,Main2Activity.class));
}
else{
Toast.makeText(MainActivity.this,"登录失败！",Toast.LENGTH_LONG).show();
}
}
public void zc(View view) {
String name=E1.getText().toString();
String pwd=E2.getText().toString();
my=new MySqlite(MainActivity.this,"userdb.db",null,1);
mydb=my.getWritableDatabase();
ContentValues CV=new ContentValues();
CV.put("userid",name);
CV.put("password",pwd);
mydb.insert("users",null,CV);
Toast.makeText(MainActivity.this,"注册完成！",Toast.LENGTH_LONG).show();
}
}

java 2
package com.example.lenovo.myapplication;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class Main2Activity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
findViewById(R.id.bt1).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent(Main2Activity.this,MainActivity.class);
startActivity(intent);
}
});
}
}

MySqlite
package com.example.lenovo.myapplication;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MySqlite extends SQLiteOpenHelper {
private static String a="create table users(id integer primary key autoincrement,userid text,password text)";
public MySqlite( Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(a);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}