Error while removing Object from Arraylist

Question

When I try to remove a int of arrayList he simply of error.

Code:

ArrayList<Integer> colors = new ArrayList<>();
colors.add(Color.rgb(119, 103, 141)); colors.add(Color.rgb(33, 10, 208)); colors.add(Color.rgb(203, 100 ,180));
colors.add(Color.rgb(249, 0 ,193)); colors.add(Color.rgb(74, 169, 94)); colors.add(Color.rgb(25, 236, 70));
colors.add(Color.rgb(235, 213, 92)); colors.add(Color.rgb(242, 206, 9)); colors.add(Color.rgb(68, 243, 220));

int teste = colors.get(3);
colors.remove(teste);

Error:

Process: lordlokon.contarapp, PID: 1840
    java.lang.RuntimeException: Unable to start activity ComponentInfo{lordlokon.contarapp/lordlokon.contarapp.MainActivity}: java.lang.ArrayIndexOutOfBoundsException: length=12; index=-458559
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2426)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2490)
        at android.app.ActivityThread.-wrap11(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1354)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5443)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
    Caused by: java.lang.ArrayIndexOutOfBoundsException: length=12; index=-458559
        at java.util.ArrayList.remove(ArrayList.java:405)
        at lordlokon.contarapp.MainActivity.randomizar(MainActivity.java:63)
        at lordlokon.contarapp.MainActivity.onCreate(MainActivity.java:52)
        at android.app.Activity.performCreate(Activity.java:6245)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1130)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2490) 
        at android.app.ActivityThread.-wrap11(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1354) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5443) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 

Answer 1

The problem is in that method remove() is overloaded:

• E remove(int index) - that removes the index-based item.

• Boolean remove(Object o) - that removes the saved object based item

The method get() returns the object(Integer in this case) stored in the indicated position.
How this object is converted to int(int teste) the method remove() to be used is one expecting an index.

Notice this line of error:

Caused by: java.lang.Arrayindexoutofboundsexception: length=12; index=-458559

You are trying to remove the index -458559, which is the value that the Arraylist has at position 3.(Color.rgb(249, 0 ,193))

One possible way to solve it will be like this:

Integer teste = colors.get(3);
colors.remove(teste);

or

int teste = colors.get(3);
colors.remove(colors.indexOf(teste));