如何修复 java.lang.ArrayIndexOutOfBoundsException: length=0;指数=-1

问题描述

我需要帮助.因此，我一直在修改 android studio，每次我使用 onTextChanged 在文本字段中键入内容时，我的应用程序都会崩溃，并且它会在 logcat java.lang.ArrayIndexOutOfBoundsException: length=0; 中打印此错误.指数=-1.我如何解决它?提前致谢.

I need help here. So I've been tinkering with android studio and my app crashes everytime I type something in a textfield using onTextChanged and it prints this error in logcat java.lang.ArrayIndexOutOfBoundsException: length=0; index=-1. How do I fix it? Thanks in advance.

这是我的 NotesFragment.java:

package com.example.reminderapp;

import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import com.google.android.material.floatingactionbutton.FloatingActionButton;

import java.util.ArrayList;

import static android.R.layout.simple_list_item_1;

public class NotesFragment extends Fragment {
    View view;
    static ArrayList<String> notes = new ArrayList<>();
    static ArrayAdapter<String> arrayAdapter;
    FloatingActionButton fabfrNotes;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        if(notes.size()==0)
        {
            view = inflater.inflate(R.layout.fragment_notes_empty, container, false);
            fabfrNotes = view.findViewById(R.id.fabNotes);
            fabfrNotes.setOnClickListener(v -> {
                Intent intent= new Intent(getContext(), NoteEditorActivity.class);
                startActivity(intent);
            });
        }
        else
        {
            view = inflater.inflate(R.layout.fragment_notes, container, false);
            ListView listView = view.findViewById(R.id.notesListView);

            arrayAdapter = new ArrayAdapter<>(view.getContext(), simple_list_item_1, notes);

            listView.setAdapter(arrayAdapter);
            listView.setOnItemClickListener((parent, view, i, id) -> {
                Intent intent = new Intent(getContext(), NoteEditorActivity.class);
                intent.putExtra("noteId", i);
                startActivity(intent);
            });
        }
        return view;
    }

}

这是我的 NoteEditorAcitivity.java:

package com.example.reminderapp;

import android.content.Intent;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;

import androidx.appcompat.app.AppCompatActivity;

public class NoteEditorActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_note_editor);

        EditText editTextTitle = findViewById(R.id.editTextNoteTitle);
        EditText editTextContent = findViewById(R.id.editTextNoteContent);

        Intent intent = getIntent();
        int noteId = intent.getIntExtra("noteId", -1);
        if(noteId!=-1){
            editTextTitle.setText(NotesFragment.notes.get(noteId));
        }

        editTextTitle.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) {
                NotesFragment.notes.set(noteId, String.valueOf(s));
                NotesFragment.arrayAdapter.notifyDataSetChanged();
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });
    }
}

这是我的日志:

java.lang.ArrayIndexOutOfBoundsException: length=0; index=-1
        at java.util.ArrayList.set(ArrayList.java:455)
        at com.example.reminderapp.NoteEditorActivity$1.onTextChanged(NoteEditorActivity.java:36)
        at android.widget.TextView.sendOnTextChanged(TextView.java:10578)
        at android.widget.TextView.handleTextChanged(TextView.java:10685)
        at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:13568)
        at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:1267)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:576)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:507)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:37)
        at android.text.method.QwertyKeyListener.onKeyDown(QwertyKeyListener.java:228)
        at android.text.method.TextKeyListener.onKeyDown(TextKeyListener.java:141)
        at android.widget.TextView.doKeyDown(TextView.java:8466)
        at android.widget.TextView.onKeyDown(TextView.java:8240)
        at android.view.KeyEvent.dispatch(KeyEvent.java:2842)
        at android.view.View.dispatchKeyEvent(View.java:14247)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at com.android.internal.policy.DecorView.superDispatchKeyEvent(DecorView.java:476)
        at com.android.internal.policy.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1861)
        at android.app.Activity.dispatchKeyEvent(Activity.java:4085)
        at androidx.core.app.ComponentActivity.superDispatchKeyEvent(ComponentActivity.java:122)
        at androidx.core.view.KeyEventDispatcher.dispatchKeyEvent(KeyEventDispatcher.java:84)
        at androidx.core.app.ComponentActivity.dispatchKeyEvent(ComponentActivity.java:140)
        at androidx.appcompat.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:569)
        at androidx.appcompat.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:59)
        at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.dispatchKeyEvent(AppCompatDelegateImpl.java:3054)
        at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:390)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:5947)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:5815)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:5310)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:5367)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:5333)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:5485)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:5341)
        at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:5542)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:5314)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:5367)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:5333)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:5341)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:5314)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:5367)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:5333)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:5518)
        at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:5676)
        at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:3179)
        at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:2721)
2021-03-02 15:49:39.538 17484-17484/com.example.reminderapp E/AndroidRuntime:     at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:2712)
        at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:3156)
        at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:143)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:335)
        at android.os.Looper.loop(Looper.java:183)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

推荐答案

当您尝试访问索引处不存在的项目时，您可能会得到异常 ArrayIndexOutOfBoundsException.假设您有 10 个元素的数组，索引从 0 到 9.如果您尝试访问第 11 个或更多索引，您将得到 ArrayIndexOutOfBoundsException.

You can get Exception ArrayIndexOutOfBoundsException when you are trying to access an item at index that doesn't exist. Let's say you have array of 10 elements with indexs from 0 to 9. If you try to access the 11th index or more you will get ArrayIndexOutOfBoundsException.

NotesFragment.notes.set(noteId, String.valueOf(s));NotesFragment.arrayAdapter.notifyDataSetChanged();

上面的第一行试图更新索引 noteId 处的数组中的项目，您收到此错误是因为该索引处没有项目存在.

The first line above is trying to update an item in array at index noteId, you are getting this error because no item exits at that index.

请确保该项目存在于索引noteId，您可以在那里添加断点并检查noteId的值

Please make sure that item exist at index noteId, you can add a break point there and inspect the value of noteId

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