shuffle numbers in an Arraylist - arraylist

Question

#SuppressLint("SetTextI18n")
public void kocokAjah (View view) {
TextView textViewCard = findViewById(R.id.textViewCard);
relativeLayoutGone.setVisibility(View.INVISIBLE);
textViewCard.setVisibility(View.VISIBLE);
int MyFirstNumber = Integer.parseInt(editNumBegin.getText().toString());
int MyLastNumber = Integer.parseInt(editNumEnd.getText().toString());
ArrayList<String> kocok = new ArrayList<>();
for (int i = MyFirstNumber; i <= MyLastNumber; i++) {
kocok.add(Integer.toString(i));
Collections.shuffle(kocok);
textViewCard.setText((CharSequence) kocok);
}
}
}
This is my code to shuffle numbers in an ArrayList thean sen it to a TextView.
but whenever i the code is executed the app crash.
log :
FATAL EXCEPTION: main
Process: com.theinmark.fernando.kocoktestmainactivity, PID: 6506
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:4020)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4015)
at android.view.View.performClick(View.java:4780) 
at android.view.View$PerformClick.run(View.java:19866) 
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
Caused by: java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.CharSequence
at com.theinmark.fernando.kocoktestmainactivity.MainActivity.kocokAjah(MainActivity.java:91)
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at android.view.View$1.onClick(View.java:4015) 
at android.view.View.performClick(View.java:4780) 
at android.view.View$PerformClick.run(View.java:19866) 
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
01-27 16:21:27.520 6506-6506/? I/Process: Sending signal. PID: 6506 SIG: 9
Any advice?
Thanks

Answer 1

In the middle of that long error message you will find this:
Caused by: java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.CharSequence
The problem is an ArrayList (regadless of what it contains) is not a CharSequence. If I remember correctly, Strings implement CharSequence, so maybe you'll want to build a string instead of a list of strings.
The quick and dirty way is to just "add" the strings together.
String kocok="";
for(...) {
kocok += Integer.toString(i);
}
The better way is to use a StringBuilder. But it's only really necessary if you add a lot of strings together.
Also note that you are calling setText on the text view inside the loop. You would typically to that after the loop.
If you want to shuffle the numbers before appending them to the string, I would recommend that you first add the numbers to an array, then after that loop shuffle once, then another loop to convert to a string, then after that set text on text field.
/* Pseudocode.*/
for (int i; ...) {
array.add(i);
}
Collections.shuffle(array);
String str=""
for (int i: array) { /* for each int i in array. */
str+=i;
}
textview.setText(str);