我有一个ListView包含创建的项目
val values = ArrayList<String>().toMutableList()
val adapter = ArrayAdapter(this, R.layout.listview_text_color, values)
adapter.add(title_editText.text!!.toString() + " - " + content_editText.text!!.toString())
我需要保存那些ListView项目,并在使用SharedPreferences(不是DB)重新打开应用程序时再次重新加载它们
这是我关于SP的实际代码:
fun saveData(values: Set<String>) {
val sharedPref = this.getPreferences(Context.MODE_PRIVATE) ?: return
with(sharedPref.edit()) {
putStringSet("test", values)
putString("title", title_editText.text!!.toString())
putString("content", content_editText.text!!.toString())
apply()
}
}
fun getData() {
val sharedPref = this.getPreferences(Context.MODE_PRIVATE) ?: return
val titleData = sharedPref.getString("title", "")
val contentData = sharedPref.getString("content", "")
Toast.makeText(this, "$titleData $contentData", Toast.LENGTH_LONG).show()
}
经过整天的研究,我找到了解决方案:
在MainActivity.kt中,将ArrayList变量创建为全局变量:
class MainActivity : AppCompatActivity() {
private var values = ArrayList<String>()
... //the rest of your code
}
然后添加这两个功能:
private fun saveData() {
val sharedPreferences = getSharedPreferences("shared preferences", MODE_PRIVATE)
val editor = sharedPreferences.edit()
val gson = Gson()
val json = gson.toJson(values)
editor.putString("task list", json)
editor.apply()
}
private fun loadData() {
val sharedPreferences = getSharedPreferences("shared preferences", MODE_PRIVATE)
val gson = Gson()
val json = sharedPreferences.getString("task list", "")
val type = object: TypeToken<ArrayList<String>>() {
}.type
if(json == null)
values = ArrayList()
else
values = gson.fromJson(json, type)
}
values
您的ArrayList 在哪里
要保存数据:
done_fab.setOnClickListener {
values.add("put your string here")
adapter.notifyDataSetChanged() //your array adapter
saveData()
}
要加载数据,只需在MainActivity中调用该函数:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
loadData()
val adapter = ArrayAdapter(this, R.layout.listview_text_color, values) //your custom arrayAdapter for the listView
... //the rest of your code
}
经过整天的研究,我找到了解决方案:
在MainActivity.kt中,将ArrayList变量创建为全局变量:
class MainActivity : AppCompatActivity() {
private var values = ArrayList<String>()
... //the rest of your code
}
然后添加这两个功能:
private fun saveData() {
val sharedPreferences = getSharedPreferences("shared preferences", MODE_PRIVATE)
val editor = sharedPreferences.edit()
val gson = Gson()
val json = gson.toJson(values)
editor.putString("task list", json)
editor.apply()
}
private fun loadData() {
val sharedPreferences = getSharedPreferences("shared preferences", MODE_PRIVATE)
val gson = Gson()
val json = sharedPreferences.getString("task list", "")
val type = object: TypeToken<ArrayList<String>>() {
}.type
if(json == null)
values = ArrayList()
else
values = gson.fromJson(json, type)
}
values
您的ArrayList 在哪里
要保存数据:
done_fab.setOnClickListener {
values.add("put your string here")
adapter.notifyDataSetChanged() //your array adapter
saveData()
}
要加载数据,只需在MainActivity中调用该函数:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
loadData()
val adapter = ArrayAdapter(this, R.layout.listview_text_color, values) //your custom arrayAdapter for the listView
... //the rest of your code
}
所有这些都是因为SharedPreferences
不支持ArrayList<String>
存储,因此最好使用JSON传递它们