OnItemClickListener 没有触发

我正在制作一个应用程序，该应用程序在 ListView 中显示了要执行的练习列表。我试图让用户从列表中选择一个项目来启动一个新活动，但我的 OnItemClickListener 没有触发。这是我的活动，（不是 listActivity，它是 appCompatActivity）：

ArrayList<Exercise> myExercises = new ArrayList<>();
AlertDialog.Builder alertDialogBuilder;
ArrayAdapter<Exercise> arrayAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list);
    refreshList();
    Button newExButton = (Button) findViewById(R.id.newExButton);

    arrayAdapter = new ArrayAdapter<Exercise>(
            this,
            android.R.layout.simple_list_item_1,
            myExercises );

    ListView lv = (ListView) findViewById(R.id.actList);
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            System.out.println("listener heard");
            // selected item
            int selection = position;
            startExercise(selection);
        }
    });

    lv.setAdapter(arrayAdapter);
}

public void refreshList(){
    setContentView(R.layout.activity_list);
    ListView lv = (ListView) findViewById(R.id.actList);

    lv.setChoiceMode(AbsListView.CHOICE_MODE_SINGLE);
    lv.setAdapter(arrayAdapter);
}

public void startExercise(int selection){

    Intent exIntent = new Intent(this, CommenceExercise.class);
    Exercise chosenEx = myExercises.get(selection);
    Bundle info = new Bundle();
    info.putLong("duration", chosenEx.getTime());
    info.putString("name", chosenEx.getName());
    info.putString("description", chosenEx.getDescription());
    exIntent.putExtras(info);
    startActivity(exIntent);
}

该列表最初是空的，但用户通过按下按钮添加项目。该按钮通过以下代码创建一个 alertDialog：

public void addNewActivity(View view) {
    //get prompts.xml view
    LayoutInflater li = LayoutInflater.from(context);
    View promptsView = li.inflate(R.layout.custom, null);

    alertDialogBuilder = new AlertDialog.Builder(
            context);

    // set prompts.xml to alertdialog builder
    alertDialogBuilder.setView(promptsView);

    final EditText userInput = (EditText) promptsView
            .findViewById(R.id.exNameInput);
    final EditText durInput = (EditText) promptsView
            .findViewById(R.id.exDurInput);

    // set dialog message
    alertDialogBuilder
            .setCancelable(false)
            .setPositiveButton("OK",
                    new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,int id) {
                                    long duration = 0;
                                    String exName;
                                    exName = userInput.getText().toString();
                                    duration = Integer.valueOf(durInput.getText().toString());
                                    myExercises.add(new Exercise(exName, duration));
                                   // create new exercise with user input
                                    refreshList();
                                }
                            })
                    .setNegativeButton("Cancel",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,int id) {
                                    dialog.cancel();
                                }
                            });
            // create alert dialog
            AlertDialog alertDialog = alertDialogBuilder.create();
            // show it
            alertDialog.show();
}

}

这是我的 xml：

<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:descendantFocusability="blocksDescendants"
tools:context="com.example.mytimer.ListActivity">

<TextView
    android:id="@+id/textView2"
    android:layout_width="146dp"
    android:layout_height="30dp"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginTop="16dp"
    android:text="Activities"
    android:textAlignment="center"
    android:textSize="24sp"
    app:layout_constraintHorizontal_bias="0.502"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    android:layout_marginStart="16dp"
    android:clickable="false"
    android:layout_marginEnd="16dp" />

<Button
    android:id="@+id/newExButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginEnd="16dp"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginStart="16dp"
    android:layout_marginTop="87dp"
    android:onClick="addNewActivity"
    android:text="New Exercise"
    android:textSize="18sp"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView2" />

<ListView
    android:id="@+id/actList"
    android:layout_width="328dp"
    android:layout_height="301dp"
    android:layout_marginBottom="16dp"
    android:layout_marginEnd="16dp"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginStart="16dp"
    android:layout_marginTop="16dp"
    android:descendantFocusability="blocksDescendants"
    android:focusable="false"
    android:clickable="false"
    android:focusableInTouchMode="false"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/newExButton"
    app:layout_constraintVertical_bias="1.0">
<requestFocus/>
</ListView>

<TextView
    android:id="@+id/debugText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="36dp"
    android:text="TextView"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    android:clickable="false"
    app:layout_constraintTop_toBottomOf="@+id/textView2" />

</android.support.constraint.ConstraintLayout>

当我点击已添加到列表中的项目时，没有任何反应。我可以说 OnItemClickListener 没有被触发，因为 System.out 行从未打印过。我不知道为什么我不能让它工作。任何帮助将不胜感激。提前致谢。