设置textview使应用程序崩溃

Question

In this onClick method I need this textView to change to one of the random lines from the array, but when I try to use this method, it just shows "Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference" and crashes the app, which is pretty weird because I did it the same way as before and the previous method works perfectly, so I'm pretty lost here.

I've tried everything I found here and in other places online, so I hope you could help me with that.

public void motivation(View v) {



    SK1 = (SeekBar) findViewById(R.id.seekBar);
    SK2 = (SeekBar) findViewById(R.id.seekBar3);
    SK3 = (SeekBar) findViewById(R.id.seekBar4);

    SK1.getProgress();
    SK2.getProgress();
    SK3.getProgress();
    quote = (TextView) findViewById(R.id.quot);

    int randomI = new Random().nextInt(quotes.length);
    String randomQuote = quotes[randomI];


    if (SK1.getProgress()>80 && SK2.getProgress()>80 && 
    SK3.getProgress()>80){

        setContentView(R.layout.motivated);
        quote.setText(randomQuote);

    } else {
        setContentView(R.layout.motivated);

        quote.setText("Keep working on it - me");
    }

}

as well as the xml of the text view

<?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"
android:id="@+id/cl">

<TextView
    android:id="@+id/quot"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    android:layout_marginLeft="8dp"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginRight="8dp"
    android:layout_marginBottom="8dp"
    android:text="@string/text_view"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />
 </android.support.constraint.ConstraintLayout>

and the error I'm getting

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.mojefajne.test, PID: 8516
java.lang.IllegalStateException: Could not execute method for 
android:onClick
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
    at android.view.View.performClick(View.java:6597)
    at android.view.View.performClickInternal(View.java:6574)
    at android.view.View.access$3100(View.java:778)
    at android.view.View$PerformClick.run(View.java:25885)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6669)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
 Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
    at android.view.View.performClick(View.java:6597) 
    at android.view.View.performClickInternal(View.java:6574) 
    at android.view.View.access$3100(View.java:778) 
    at android.view.View$PerformClick.run(View.java:25885) 
    at android.os.Handler.handleCallback(Handler.java:873) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:193) 
    at android.app.ActivityThread.main(ActivityThread.java:6669) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
    at com.example.mojefajne.test.MainActivity.motivation(MainActivity.java:100)
    at java.lang.reflect.Method.invoke(Native Method) 
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
    at android.view.View.performClick(View.java:6597) 
    at android.view.View.performClickInternal(View.java:6574) 
    at android.view.View.access$3100(View.java:778) 
    at android.view.View$PerformClick.run(View.java:25885) 
    at android.os.Handler.handleCallback(Handler.java:873) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:193) 
    at android.app.ActivityThread.main(ActivityThread.java:6669) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

MainActivity.java:100 being of course the setText command.

Thanks for any help!

Answer 1

I think you passed a layout containing a textView to a motivation method. If I am right then you need to find the textView as: quote = (TextView) v.findViewById(R.id.quot);