我正在尝试制作一个Android应用程序，它会在按钮点击时显示Toast。 Toast包含用户在edittext字段中输入的数字。问题是我输入文本到edittext（数字）字段，按钮点击，Toast没有显示我输入的文本。吐司完全是空白的。这是我的代码： -
activity.Java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class login extends AppCompatActivity {
String username, password;
Button payNGO, payGO;
EditText usernameField, passwordField;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
setContentView(R.layout.activity_login);
payNGO = (Button) findViewById(R.id.payngo);
payGO = (Button) findViewById(R.id.paygo);
usernameField = (EditText) findViewById(R.id.forno);
passwordField = (EditText) findViewById(R.id.dob);
username = usernameField.getText().toString();
password = passwordField.getText().toString();
payNGO.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(login.this, username, Toast.LENGTH_LONG).show();
}
});
}
}
Activity.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".login"
android:background="@drawable/back">
<ImageView
android:id="@+id/imageView"
android:layout_width="150dip"
android:layout_height="150dip"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toTopOf="@+id/forno"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.438"
app:srcCompat="@drawable/ico" />
<EditText
android:id="@+id/forno"
android:layout_width="match_parent"
android:layout_height="40dip"
android:layout_marginBottom="20dp"
android:layout_marginEnd="30dip"
android:layout_marginStart="30dip"
android:background="@drawable/rect_back"
android:ems="10"
android:hint="Number"
android:inputType="number"
android:paddingEnd="10dp"
android:paddingStart="10dp"
app:layout_constraintBottom_toTopOf="@+id/dob"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.562"
app:layout_constraintStart_toStartOf="parent" />
<EditText
android:id="@+id/dob"
android:layout_width="match_parent"
android:layout_height="40dip"
android:layout_marginBottom="124dp"
android:layout_marginEnd="30dip"
android:layout_marginStart="30dip"
android:background="@drawable/rect_back"
android:ems="10"
android:hint="Date of Birth"
android:inputType="numberPassword"
android:paddingEnd="10dp"
android:paddingStart="10dp"
app:layout_constraintBottom_toTopOf="@+id/linearLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.562"
app:layout_constraintStart_toStartOf="parent" />
<LinearLayout
android:id="@+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="92dp"
android:orientation="horizontal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="@+id/payngo"
android:layout_width="wrap_content"
android:layout_height="40dip"
android:layout_marginEnd="20dip"
android:layout_marginStart="15dip"
android:layout_weight="1"
android:background="@drawable/rect_back_button"
android:text="Pay (NGO)"
tools:layout_editor_absoluteX="204dp"
tools:layout_editor_absoluteY="440dp" />
<Button
android:id="@+id/paygo"
android:layout_width="wrap_content"
android:layout_height="40dip"
android:layout_marginEnd="15dip"
android:layout_marginStart="20dip"
android:layout_weight="1"
android:background="@drawable/rect_back_button"
android:text="Pay (GO)"
tools:layout_editor_absoluteX="92dp"
tools:layout_editor_absoluteY="440dp" />
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:background="@drawable/rect_back_text"
android:orientation="horizontal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="50dip"
android:layout_weight="1"
android:text="@string/linef"
android:textAlignment="textEnd"
android:textColor="#fff"
android:textSize="20sp"
tools:layout_editor_absoluteX="30dp"
tools:layout_editor_absoluteY="505dp" />
<ImageView
android:id="@+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:scaleType="fitCenter"
app:srcCompat="@drawable/heart"
tools:ignore="VectorDrawableCompat" />
<TextView
android:id="@+id/textView5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="50dip"
android:layout_weight="1"
android:text="@string/linee"
android:textColor="#fff"
android:textSize="20sp"
tools:layout_editor_absoluteX="171dp"
tools:layout_editor_absoluteY="505dp" />
</LinearLayout>
</android.support.constraint.ConstraintLayout>
由于您获得了onCreate中的值，即使在输入任何内容之前也会执行该值，您的Toast会显示空白数据。
将getText()方法移动到onClick以达到预期结果，如下所示：
payNGO.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
username = usernameField.getText().toString();
password = passwordField.getText().toString();
Toast.makeText(login.this, username, Toast.LENGTH_LONG).show();
}
});
Toast.makeText(login.this, usernameField.getText().toString(), Toast.LENGTH_LONG).show();
你可以使用这个代码它肯定工作..