android - XML 显示白屏

Question

我正在尝试在 Kotlin 中为我的应用程序登录并创建帐户页面。问题是我在 AndroidManifest 上添加了创建帐户页面作为打开应用程序时的第一页，它只显示白屏。我注意到在 Android Studio 中有一个设计选项卡，页面显示完全符合我的要求。你能帮助我吗？

这是我的 XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/gradient_background">

<TextView
    android:id="@+id/register"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="@string/create_account"
    android:textSize="30sp"
    android:textColor="@color/white"
    android:gravity="center"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.498"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.132" />


<androidx.cardview.widget.CardView
    android:id="@+id/myCardView"
    android:layout_width="393dp"
    android:layout_height="451dp"
    android:layout_gravity="center"
    android:layout_margin="4dp"
    app:cardBackgroundColor="@color/cardsColor"
    app:cardCornerRadius="12dp"
    app:cardElevation="0dp"
    app:cardUseCompatPadding="true"
    app:contentPadding="12sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <LinearLayout
        android:layout_width="361dp"
        android:layout_height="426dp"
        android:orientation="vertical"
        android:padding="16dp"
        android:paddingStart="16dp"
        android:paddingLeft="16dp"
        android:paddingTop="16dp"
        android:paddingEnd="16dp"
        android:paddingRight="16dp"
        android:paddingBottom="16dp"
        android:weightSum="5.5">


        <EditText
            android:id="@+id/email"
            android:layout_width="match_parent"
            android:layout_height="70dp"
            android:layout_marginBottom="10dp"
            android:background="@drawable/edit_text_stroke"
            android:gravity="center"
            android:hint="@string/email"
            android:minLines="2"

            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.213"
            android:importantForAutofill="no" />

        <EditText
            android:id="@+id/password"
            android:layout_width="match_parent"
            android:layout_height="70dp"
            android:layout_marginBottom="10dp"
            android:background="@drawable/edit_text_stroke"
            android:gravity="center"
            android:hint="@string/password"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.3"
            android:importantForAutofill="no" />



    </LinearLayout>
</androidx.cardview.widget.CardView>

<Button
    android:id="@+id/register_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:background="@drawable/button_round_corners"
    android:gravity="center"
    android:padding="12dp"
    android:text="@string/create_account"
    android:textColor="@color/white"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.164"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/myCardView"
    app:layout_constraintVertical_bias="0.535" />

<Button
    android:id="@+id/login_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/button_round_corners"
    android:padding="12dp"
    android:text="@string/login"
    android:textColor="@color/white"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.81"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/myCardView"
    app:layout_constraintVertical_bias="0.535" />

</androidx.constraintlayout.widget.ConstraintLayout>

和我的科特林课

package projeto.a43796.dashboard

import android.content.Intent
import android.os.Bundle
import android.os.PersistableBundle
import android.text.TextUtils
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseUser
import kotlinx.android.synthetic.main.activity_create_account.*

class CreateAccount : AppCompatActivity() {

lateinit var registerButton: Button
lateinit var email: EditText
lateinit var password: EditText

override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
    super.onCreate(savedInstanceState, persistentState)
    setContentView(R.layout.activity_create_account)

    registerButton = findViewById(R.id.register_button)
    email = findViewById(R.id.email)
    password = findViewById(R.id.password)


    registerButton.setOnClickListener(){
        when{
            TextUtils.isEmpty(email.text.toString().trim{it <= ' '}) -> {
                Toast.makeText(
                    this@CreateAccount,
                    "Please enter your e-mail",
                    Toast.LENGTH_SHORT
                ).show()
            }

            TextUtils.isEmpty(password.text.toString().trim{it <= ' '}) -> {
                Toast.makeText(
                    this@CreateAccount,
                    "Please enter your password",
                    Toast.LENGTH_SHORT
                ).show()
            }

            else -> {
                val email: String = email.text.toString().trim{it <= ' '}
                val passord: String = password.text.toString().trim{it <= ' '}

                FirebaseAuth.getInstance().createUserWithEmailAndPassword(email, passord)
                    .addOnCompleteListener { task ->
                        if (task.isSuccessful) {
                            val firebaseUser: FirebaseUser = task.result!!.user!!

                            Toast.makeText(
                                this@CreateAccount,
                                "Account Created",
                                Toast.LENGTH_SHORT
                            ).show()

                            val intent =
                                Intent(this@CreateAccount, Dashboard::class.java)
                            intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
                            intent.putExtra("user_id", firebaseUser.uid)
                            intent.putExtra("email_user", email)
                            startActivity(intent)
                            finish()
                        }
                        else{
                            Toast.makeText(
                                this@CreateAccount,
                                task.exception!!.message.toString(),
                                Toast.LENGTH_SHORT
                            ).show()
                        }
                    }

            }
        }
    }
} 

}

标签： androidxmlkotlinandroid-emulator