Java 如何使用内部存储器存储自定义对象的ArrayList?
我想使用内部存储器存储名为WordList的自定义对象的ArrayList 这是我的密码:Java 如何使用内部存储器存储自定义对象的ArrayList?,java,android,arraylist,internal-storage,Java,Android,Arraylist,Internal Storage,我想使用内部存储器存储名为WordList的自定义对象的ArrayList 这是我的密码: @SuppressWarnings("serial") public class WordList extends MainActivity implements Serializable { public String name; public ArrayList<String> wordarray; public ArrayList<String> definitionarr
@SuppressWarnings("serial")
public class WordList extends MainActivity implements Serializable {
public String name;
public ArrayList<String> wordarray;
public ArrayList<String> definitionarray;
public WordList(String newName)
{
this.name = newName;
this.wordarray = new ArrayList<String>();
this.definitionarray = new ArrayList<String>();
}
public String getName()
{
return name;
}
private void writeObject(ObjectOutputStream out) throws IOException {
out.writeUTF(name);
out.writeObject(wordarray);
out.writeObject(definitionarray);
}
private void readObject(ObjectInputStream in) throws IOException,
ClassNotFoundException {
name = in.readUTF();
wordarray = (ArrayList<String>) in.readObject();
definitionarray = (ArrayList<String>) in.readObject();
}
}
@SuppressWarnings(“串行”)
公共类WordList扩展MainActivity实现可序列化{
公共字符串名称;
公共数组列表字数组;
公共数组列表定义数组;
公共单词列表(字符串newName)
{
this.name=newName;
this.wordarray=new ArrayList();
this.definitionarray=新的ArrayList();
}
公共字符串getName()
{
返回名称;
}
私有void writeObject(ObjectOutputStream out)引发IOException{
out.writeUTF(姓名);
out.writeObject(字数组);
out.writeObject(定义数组);
}
私有void readObject(ObjectInputStream in)引发IOException,
ClassNotFoundException{
name=in.readUTF();
.readObject()中的wordarray=(ArrayList);
.readObject()中的definitionarray=(ArrayList);
}
}
以下是主要活动:
public class MainActivity extends Activity {
private EditText text;
private ArrayList<WordList> lists = new ArrayList<WordList>();
private TextView textview;
FileOutputStream fos;
String filePath;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (EditText) findViewById(R.id.editText1);
textview = (TextView) findViewById(R.id.test);
filePath = getApplicationContext().getFilesDir().getPath().toString() + ".fileName.txt";
}
public void onClick(View view) throws FileNotFoundException {
switch (view.getId()) {
case R.id.addtoarray:
String input = text.getText().toString();
WordList list = new WordList(input);
lists.add(list);
break;
case R.id.save:
try {
File f = new File(filePath);
FileOutputStream fos = new FileOutputStream(f, true);
ObjectOutputStream oos = new ObjectOutputStream(fos);
Toast.makeText(getApplicationContext(), "Wrote " + String.valueOf(lists.size() + "objects to file!"), Toast.LENGTH_LONG).show();
oos.writeInt(lists.size());
for(int i=0; i<lists.size(); i++)
{
oos.writeObject(lists.get(i));
}
oos.close();
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
case R.id.load:
File saveFile = new File(filePath);
if (saveFile.exists())
{
Toast.makeText(getApplicationContext(), "File found!",
Toast.LENGTH_SHORT).show();
try {
FileInputStream fis = new FileInputStream(saveFile);
ObjectInputStream ois = new ObjectInputStream(fis);
int num = ois.readInt();
for(int i = 0; i<num; i++)
{
WordList o = (WordList) ois.readObject();
lists.add(o);
}
fis.close();
ois.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (StreamCorruptedException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
} else {
Toast.makeText(getApplicationContext(), "File not found!",
Toast.LENGTH_SHORT).show();
}
textview.setText(lists.get(0).getName());
break;
}
}
公共类MainActivity扩展活动{
私人编辑文本;
private ArrayList list=new ArrayList();
私有文本视图文本视图;
文件输出流;
字符串文件路径;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text=(EditText)findViewById(R.id.editText1);
textview=(textview)findViewById(R.id.test);
filePath=getApplicationContext().getFilesDir().getPath().toString()+“.fileName.txt”;
}
公共void onClick(视图)引发FileNotFoundException{
开关(view.getId()){
案例R.id.addtoarray:
字符串输入=text.getText().toString();
单词列表=新单词列表(输入);
列表。添加(列表);
打破
案例R.id.save:
试一试{
文件f=新文件(文件路径);
FileOutputStream fos=新的FileOutputStream(f,true);
ObjectOutputStream oos=新的ObjectOutputStream(fos);
Toast.makeText(getApplicationContext(),“writed”+String.valueOf(lists.size()+“objects to file!”),Toast.LENGTH\u LONG.show();
oos.writeInt(lists.size());
对于(int i=0;i您可以分两步执行:
1.您需要能够将WordList对象转换为字符串对象/变量,反之亦然。您可以使用注释中的建议来解决问题。
2.然后,您将能够使用SharedReferences保存字符串对象
在代码中,您将执行以下操作:
1.当需要在内存中保存对象时,可将其转换为字符串:
String my_object = GetStringFromMyObject(object_to_save);
2.然后将其保存在SharedReferences中:
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = prefs.edit();
editor.putString("my_object_key", my_object);
3.最后,您可以随时恢复该值:
MyObject object_to_restore = GetMyObjectFromString(prefs.getString("my_object_key", "default_value));
使用GSON库,将对象转换为字符串对象
,并存储在内部存储器中(共享首选项)