Question

我有一个问题，当我单击登录按钮时，Toast make文本不会显示，并且我不知道这是怎么回事，因为

我看不到任何错误，当我将toast.maketext更改为Intent时，应用程序强制关闭。希望有人能帮忙。

MainActivity.java

public class MainActivity extends AppCompatActivity {

    EditText email;
    EditText password;
    Button login;
    Button signup;
    DBHelper db;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        db = new DBHelper(this);
        email = findViewById(R.id.editText_email);
        password = findViewById(R.id.editText_password);
        login = findViewById(R.id.btnlogin);
        signup = findViewById(R.id.btnsignup);


        signup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent signupIntent = new Intent(MainActivity.this, SignUp.class);
                startActivity(signupIntent);

            }

        });

        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                    String user = email.getText().toString();
                    String pass = password.getText().toString();

                    Boolean res = db.checkAcc(user,pass);
                    if(res==true){
                        Toast.makeText(MainActivity.this,"You are logged in",Toast.LENGTH_SHORT);
                    }
                    else{
                        Toast.makeText(MainActivity.this,"Please Enter Again",Toast.LENGTH_SHORT);
                    }


            }
        });

    }
}

DBHelper.java

public class DBHelper extends SQLiteOpenHelper {
    public static final String DATABASE_NAME="register.db";
    public static final String TABLE_NAME="register";
    public static final String COL_1="ID";
    public static final String COL_2="email";
    public static final String COL_3="password";


    public DBHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL("CREATE TABLE register (ID INTEGER PRIMARY KEY AUTOINCREMENT,email TEXT UNIQUE, password TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
        sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(sqLiteDatabase);
    }

    public long AddAcc(String email, String password){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put("email",email);
        contentValues.put("password",password);
        long res = db.insert("register",null,contentValues);
        db.close();
        return res;
    }

    public boolean checkAcc(String username,String password){
       String[] columns = { COL_1 };
       SQLiteDatabase db = getReadableDatabase();
       String selection = COL_2  + "=?" + " and " + COL_3 + "=?";
       String[] selectionArgs = {username,password};
       Cursor cursor = db.query(TABLE_NAME,columns,selection,selectionArgs,null,null,null);
       int count = cursor.getCount();
       cursor.close();
       db.close();

       if(count>0)
           return true;
       else
           return false;
    }
}

Answer 1

您必须在吐司末添加.show()，使其成为visible，所以

使用此：

if(res==true){
   Toast.makeText(MainActivity.this,"You are logged in",Toast.LENGTH_SHORT).show();
     }
    else{
    Toast.makeText(MainActivity.this,"Please Enter Again",Toast.LENGTH_SHORT).show();
 }

代替此：

 if(res==true){
    Toast.makeText(MainActivity.this,"You are logged in",Toast.LENGTH_SHORT);
       }
       else{
     Toast.makeText(MainActivity.this,"Please Enter Again",Toast.LENGTH_SHORT);
 }

Answer 2

使用此：

Toast.makeText(MainActivity.this,"You are logged in",Toast.LENGTH_SHORT).show();

代替：

Toast.makeText(MainActivity.this,"You are logged in",Toast.LENGTH_SHORT);

为什么我的Toast.makeText没有显示任何内容

2 个答案: