public Boolean isUserinfo(String name,String pass) { String nameString=name; String passString=pass; databaseHelper=new DatebaseHelper(Login.this,DATABASE_NAME,null,DATABASE_VERSION); db = databaseHelper.getReadableDatabase(); try{ Cursor cursor=db.query(TABLE_NAME, new String[]{"name","password"},"name=?",new String[]{nameString},null,null,"password"); while(cursor.moveToNext()) { @SuppressLint("Range") String password=cursor.getString(cursor.getColumnIndex("password")); if(passString.equals(password)) { new AlertDialog.Builder(Login.this).setTitle("正确") .setMessage("成功登录").setPositiveButton("确定", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub Intent intent = new Intent(Login.this,MainActivity.class); startActivity(intent); } }).show(); break; } else { Toast.makeText(this, "用户名密码不正确",Toast.LENGTH_LONG).show(); break; } } }catch(SQLiteException e){ CreatTable(); } return false; }代码解释

这段代码是用来验证用户输入的用户名和密码是否匹配的方法。该方法首先获取数据库操作对象db，然后使用query方法查询数据库中是否存在该用户的记录。如果存在，就遍历该用户的记录，获取该用户的密码，然后将用户输入的密码与数据库中的密码进行比较，如果匹配，则弹出一个对话框提示用户登录成功，并且跳转到主页面；否则，弹出一个Toast提示用户名或密码不正确。

在代码中，如果查询数据库出现异常，会调用CreatTable方法重新创建表格。最后，该方法返回false，但实际上该返回值没有被使用。

相关问题

public Animal(String name, int age) { this.name = name; this.age = age; }这不是提供了吗

是的，你说得对，我之前的回答有些模糊。在这个例子中，父类 `Animal` 已经提供了带有参数的构造函数 `Animal(String name, int age)` 来初始化属性，因此在子类 `Cat` 和 `Dog` 中可以使用 `super(name, age)` 来调用父类的构造函数，以初始化继承自父类的属性 `name` 和 `age`。

在这种情况下，子类的构造函数中可以不写 `super(name, age)`，编译器会自动调用父类的带有参数的构造函数，但是建议在子类的构造函数中显式地调用父类的构造函数，以提高代码的可读性和可维护性。

因此，以下是更新后的代码示例：

public class Animal {
    private String name;
    private int age;

    public Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public void eat() {
        System.out.println("The animal is eating.");
    }
    
    public void sleep() {
        System.out.println("The animal is sleeping.");
    }
}

public class Cat extends Animal {
    private boolean isIndoor;

    public Cat(String name, int age, boolean isIndoor) {
        super(name, age);
        this.isIndoor = isIndoor;
    }

    public void meow() {
        System.out.println("The cat is meowing.");
    }

    @Override
    public void eat() {
        System.out.println("The cat is eating fish.");
    }
}

public class Dog extends Animal {
    private String breed;

    public Dog(String name, int age, String breed) {
        super(name, age);
        this.breed = breed;
    }

    public void bark() {
        System.out.println("The dog is barking.");
    }

    @Override
    public void eat() {
        System.out.println("The dog is eating meat.");
    }
}

public static Map<String, Boolean> SG = new HashMap<>();

As an AI language model, I don't have any context or information about what this code is trying to accomplish. However, I can explain what the code is doing in general.

This line of code initializes a new HashMap called "SG" with a key type of String and a value type of Boolean. HashMap is a data structure in Java that allows for efficient key-value mapping and retrieval. The purpose of this specific HashMap is not clear without any additional context.