Question

我正在尝试在按下edittext上的回车键时简单地向列表视图添加内容。我还在一个按钮上有一个onclick监听器，它将调用相同的函数将该单词添加到listview。按钮工作正常，直到我添加了textwatcher。现在，如果我正在调用的函数在监听器中，如果我按Enter键或按下按钮，整个应用程序崩溃。如果我从textwatcher中删除该类，那么如果我按下Enter键，应用程序不会崩溃，但如果我按下按钮，它就会崩溃。有任何想法吗？我没有永远做过android，所以我完全卡住了。

XML

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/myEditText"
    android:hint="Enter a new item"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_toLeftOf="@+id/myDoneButton"
    android:layout_toStartOf="@+id/myDoneButton"
    android:layout_above="@+id/myListView"/>

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Add Item"
    android:id="@+id/myDoneButton"
    android:layout_alignParentTop="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:onClick="onAddItem"
    />

JAVA

//On enter listener for mEditText (within oncreate)
mEditText.addTextChangedListener(new TextWatcher() {
   @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {

        }

        @Override
        public void afterTextChanged(Editable s) {
            if (s.charAt(s.length() - 1) == '\n') { 
                onAddItem(mListView);
                Log.d("TEST RESPONSE", "Enter was pressed");
            }
        }
    });

//Outside of oncreate
public void onAddItem(View v) {
    String itemText = mEditText.getText().toString();
    itemsAdapter.add(itemText);
    mEditText.setText("");
    writeItems();
}

以下是Logcat的相关信息

04-11 16:26:23.619 13377-13377/com.ivieinc.groceryapp E/AndroidRuntime:
FATAL EXCEPTION: main Process: com.ivieinc.groceryapp, PID: 13377                          java.lang.IllegalStateException: Could not execute method for android:onClick 
... (removed for clarity)                                                                 
Caused by: java.lang.reflect.InvocationTargetException 
... (removed for clarity)
Caused by: java.lang.IndexOutOfBoundsException: charAt: -1 < 0                                                                       
at android.text.SpannableStringBuilder.charAt(SpannableStringBuilder.java:117)
at com.ivieinc.groceryapp.MainActivity$1.afterTextChanged(MainActivity.java:69)
at android.widget.TextView.sendAfterTextChanged(TextView.java:8007)
at android.widget.TextView.setText(TextView.java:4351)
at android.widget.TextView.setText(TextView.java:4199)
at android.widget.EditText.setText(EditText.java:84)
at android.widget.TextView.setText(TextView.java:4174)
at com.ivieinc.groceryapp.MainActivity.onAddItem(MainActivity.java:108)
... (removed for clarity)

Answer 1

您的错误在这里：

if (s.charAt(s.length() - 1) == '\n') {

由于s为空，s.length为零，并且您试图在索引-1处获取char ...

您必须验证可修改的

编辑文本的Android textlistener崩溃程序

1 个答案: