Question

过去几天我一直在尝试保存并加载ArrayList个字符串，而我似乎无法让它工作。没有错误，但它甚至不再向ListView添加项目。我也不认为它也在拯救。请帮忙？

package com.evolvr.productivityapp;

import android.app.ListActivity;

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;

import android.view.MotionEvent;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;

import java.io.*;


import java.util.ArrayList;

public class toDoList extends ListActivity {
    private Button done;
    private ListView theList;
    private EditText listItem;
    private ArrayList<String> listOfList = new ArrayList<String>();
    private ArrayAdapter<String> adapter;


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

        done = (Button) findViewById(R.id.doneBtn);
        theList = (ListView) findViewById(android.R.id.list);
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, listOfList);

        FileInputStream fis;
        ObjectInputStream ois;

        done.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                listItem = (EditText) findViewById(R.id.taskTextView);
                if (listItem.getText().toString() == "") {

                } else { //adding items to the listview
                    listOfList.add(listItem.getText().toString());
                    listItem.setText("");
                    adapter.notifyDataSetChanged();
                }
            }
        });
        setListAdapter(adapter);
        try{
            fis = openFileInput("ToDo");
            ois = new ObjectInputStream(fis);
            listOfList = (ArrayList<String>) ois.readObject();
        }catch(IOException e){
            Log.e("ToDoInput", "Can't import todo");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }


    }

    @Override
    protected void onPause(){
        super.onPause();
        FileOutputStream fos;
        ObjectOutputStream ous = null;

        try{
            fos = openFileOutput("ToDo", Activity.MODE_PRIVATE);
            ous = new ObjectOutputStream(fos);
            ous.writeObject(listOfList);
        }catch(IOException e){
            Log.e("ToDo", "Something wrong with output?");
        }finally {
            try{
                if(ous != null) {
                    ous.close();
                }
            }catch(IOException e){
                e.printStackTrace();
            }
        }


    }

Answer 1

您可以在传递

之前检查列表项是否为空或为空

done.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
    listItem = (EditText) findViewById(R.id.taskTextView);
    if (isEditTextNotNull(listItem)) {
        //adding items to the listview
        listOfList.add(listItem.getText().toString());
        listItem.setText("");
        adapter.notifyDataSetChanged();
    }
}
});

private boolean isEditTextNotNull(EditText listItem) {
  return listItem.getText().toString()!=null && !listItem.getText().toString().isEmpty();
}

Answer 2

尝试从此示例中采用相同的概念：

private ArrayList<String> listOfList = new ArrayList<String>();
private ListView LView;
String someText = "This is some text that will be added";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_to_do_list);
listOfList.add(someText);

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, listOfList);
    LView.setAdapter(adapter); //Adds to the List View
}

保存并检索ArrayList，然后将其添加到ListView

2 个答案: