单击按钮后不显示文本视图-Android

Question

我在Android Studio中遇到“文本视图”和“按钮”的问题。 我想在单击按钮时更新文本视图，但是它不起作用。 这是我的代码：

activity_distance_to_run.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=".MainActivity"
tools:layout_editor_absoluteY="25dp">


<TextView
    android:id="@+id/Distancerun2"
    android:layout_width="126dp"
    android:layout_height="50dp"
    android:layout_marginTop="50dp"
    android:text="Distance to ....."
    android:textSize="14sp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<Button
    android:id="@+id/distancetorun"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginEnd="10dp"
    android:layout_marginRight="10dp"
    android:text="run"
    app:layout_constraintBaseline_toBaselineOf="@+id/distancetoride"
    app:layout_constraintEnd_toStartOf="@+id/distancetoride"
    app:layout_constraintStart_toStartOf="parent" />

<Button
    android:id="@+id/distancetoride"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginEnd="9dp"
    android:layout_marginRight="9dp"
    android:layout_marginTop="32dp"
    android:text="ride a bicycle"
    app:layout_constraintEnd_toStartOf="@+id/distancetoswim"
    app:layout_constraintStart_toEndOf="@+id/distancetorun"
    app:layout_constraintTop_toBottomOf="@+id/Distancerun2" />

<Button
    android:id="@+id/distancetoswim"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="swim"
    app:layout_constraintBaseline_toBaselineOf="@+id/distancetoride"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toEndOf="@+id/distancetoride" />

<Button
    android:id="@+id/yes"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="32dp"
    android:layout_marginStart="32dp"
    android:text="I did it !!"
    app:layout_constraintBaseline_toBaselineOf="@+id/no"
    app:layout_constraintStart_toStartOf="parent" />

<Button
    android:id="@+id/no"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="116dp"
    android:layout_marginEnd="16dp"
    android:layout_marginRight="16dp"
    android:text="I don't want to do it !!"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView1" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:layout_marginBottom="23dp"
    android:layout_marginEnd="25dp"
    android:layout_marginLeft="25dp"
    android:layout_marginRight="25dp"
    android:layout_marginStart="25dp"
    android:layout_marginTop="221dp"
    android:autoText="true"
    android:clickable="true"
    android:enabled="false"
    android:freezesText="false"
    android:text="Elo ziomek"
    android:textSize="24sp"
    app:layout_constraintBottom_toTopOf="@+id/no"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

distancetorun.java

package pl.agcode.sqliteexample;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class distance_to_run extends Activity {
Button distancetorun;
TextView txtView;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_distance_to_run);
    distancetorun = (Button) findViewById(R.id.distancetorun);
    txtView = (TextView) findViewById(R.id.textView1);
    distancetorun.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            txtView.setText("NewText");
        }
        });
    }
}

感谢您的帮助，我将尝试修复它，但不知道如何。 这对我来说很重要。 :)

Answer 1

看起来一切都很好，除了textview1颜色。

在布局xml中为textview1添加以下行

 <TextView
    android:id="@+id/textView1"
    android:textColor="@android:color/black"

启动应用程序后

单击运行按钮后