Java 在android中退出活动后,如何保留我的listview?
我有一个listview,每当用户单击add按钮时,我都希望在其中存储特定的数据。然而,到目前为止,我在实施方面几乎没有成功。我知道这必须通过使用SharedReferences来完成,并尝试实现SharedReferences的保存状态和恢复状态,但我的listview仍然只添加当前单击的元素Java 在android中退出活动后,如何保留我的listview?,java,android,sharedpreferences,android-sharedpreferences,Java,Android,Sharedpreferences,Android Sharedpreferences,我有一个listview,每当用户单击add按钮时,我都希望在其中存储特定的数据。然而,到目前为止,我在实施方面几乎没有成功。我知道这必须通过使用SharedReferences来完成,并尝试实现SharedReferences的保存状态和恢复状态,但我的listview仍然只添加当前单击的元素 package com.example.daniel.pset3_daniel_jacob; import android.content.SharedPreferences; import
package com.example.daniel.pset3_daniel_jacob;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
public class listview extends AppCompatActivity {
ArrayList<String> dataa;
@Override
protected void onCreate(Bundle savedInstanceState) {
onRestoredPreferences();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_listview);
Bundle extras = getIntent().getExtras();
String dataExtra = extras.getString("key");
dataa = new ArrayList<String>();
dataa.add(dataExtra);
ListView listView = (ListView) findViewById(R.id.listview);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, dataa);
assert listView != null;
listView.setAdapter(adapter);
Savedpreferences(dataa);
}
public void Savedpreferences(List<String> dataa) {
SharedPreferences preferences = this.getSharedPreferences("object", 0);
SharedPreferences.Editor editor = preferences.edit();
List<String> arraylist = new ArrayList<String>(dataa);
Set<String> newset = new HashSet<String>(arraylist);
editor.putStringSet("stringset", newset);
editor.commit();
}
public void onRestoredPreferences()
{
SharedPreferences preferences = getApplicationContext().getSharedPreferences("object", 0);
Set<String> getdataback = preferences.getStringSet("stringset", null);
List <String> arraylist = new ArrayList<String>(getdataback);
}
}
package com.example.daniel.pset3_daniel_jacob;
导入android.content.SharedReferences;
导入android.preference.PreferenceManager;
导入android.support.v7.app.AppActivity;
导入android.os.Bundle;
导入android.widget.ArrayAdapter;
导入android.widget.ListView;
导入java.io.Serializable;
导入java.util.ArrayList;
导入java.util.HashSet;
导入java.util.List;
导入java.util.Set;
公共类listview扩展了AppCompatActivity{
arraylistdataa;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
onRestoredPreferences();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u列表视图);
Bundle extras=getIntent().getExtras();
字符串dataExtra=extras.getString(“key”);
dataa=新的ArrayList();
dataa.add(dataExtra);
ListView ListView=(ListView)findViewById(R.id.ListView);
ArrayAdapter=新的ArrayAdapter(这个,android.R.layout.simple_list_item_1,android.R.id.text1,dataa);
断言listView!=null;
setAdapter(适配器);
保存数据引用(dataa);
}
公共void savedReferences(列表数据A){
SharedReferences首选项=this.getSharedReferences(“对象”,0);
SharedReferences.Editor=首选项.edit();
List arraylist=新的arraylist(dataa);
Set newset=newhashset(arraylist);
编辑器.putStringSet(“stringset”,新闻集);
commit();
}
在RestoredPreferences()上公共无效
{
SharedReferences首选项=getApplicationContext()。GetSharedReferences(“对象”,0);
Set getdataback=preferences.getStringSet(“stringset”,null);
List arraylist=新建arraylist(getdataback);
}
}
我希望有人能帮助我告诉我我做错了什么请尝试下面的代码,如果有任何问题,请告诉我
public class ListviewActivity extends AppCompatActivity {
ArrayList<String> dataa;
List <String> arraylist = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
onRestoredPreferences();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_listview);
Bundle extras = getIntent().getExtras();
String dataExtra = extras.getString("key");
dataa = new ArrayList<String>();
dataa.addAll(arraylist);
dataa.add(dataExtra);
ListView listView = (ListView) findViewById(R.id.listview);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, dataa);
assert listView != null;
listView.setAdapter(adapter);
Savedpreferences(dataa);
}
public void Savedpreferences(List<String> dataa) {
SharedPreferences preferences = this.getSharedPreferences("object", 0);
SharedPreferences.Editor editor = preferences.edit();
List<String> arraylist = new ArrayList<String>(dataa);
Set<String> newset = new HashSet<String>(arraylist);
editor.putStringSet("stringset", newset);
editor.commit();
}
public void onRestoredPreferences()
{
SharedPreferences preferences = getApplicationContext().getSharedPreferences("object", 0);
Set<String> getdataback = preferences.getStringSet("stringset", null);
arraylist.clear();
arraylist.addAll(getdataback);
}
}
公共类ListviewActivity扩展了AppCompatActivity{
arraylistdataa;
List arraylist=新建arraylist();
@凌驾
创建时受保护的void(Bundle savedInstanceState){
onRestoredPreferences();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u列表视图);
Bundle extras=getIntent().getExtras();
字符串dataExtra=extras.getString(“key”);
dataa=新的ArrayList();
dataa.addAll(arraylist);
dataa.add(dataExtra);
ListView ListView=(ListView)findViewById(R.id.ListView);
ArrayAdapter=新的ArrayAdapter(这个,android.R.layout.simple_list_item_1,android.R.id.text1,dataa);
断言listView!=null;
setAdapter(适配器);
保存数据引用(dataa);
}
公共void savedReferences(列表数据A){
SharedReferences首选项=this.getSharedReferences(“对象”,0);
SharedReferences.Editor=首选项.edit();
List arraylist=新的arraylist(dataa);
Set newset=newhashset(arraylist);
编辑器.putStringSet(“stringset”,新闻集);
commit();
}
在RestoredPreferences()上公共无效
{
SharedReferences首选项=getApplicationContext()。GetSharedReferences(“对象”,0);
Set getdataback=preferences.getStringSet(“stringset”,null);
arraylist.clear();
addAll(getdataback);
}
}
尝试下面的代码,如果有任何问题,请告诉我
public class ListviewActivity extends AppCompatActivity {
ArrayList<String> dataa;
List <String> arraylist = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
onRestoredPreferences();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_listview);
Bundle extras = getIntent().getExtras();
String dataExtra = extras.getString("key");
dataa = new ArrayList<String>();
dataa.addAll(arraylist);
dataa.add(dataExtra);
ListView listView = (ListView) findViewById(R.id.listview);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, dataa);
assert listView != null;
listView.setAdapter(adapter);
Savedpreferences(dataa);
}
public void Savedpreferences(List<String> dataa) {
SharedPreferences preferences = this.getSharedPreferences("object", 0);
SharedPreferences.Editor editor = preferences.edit();
List<String> arraylist = new ArrayList<String>(dataa);
Set<String> newset = new HashSet<String>(arraylist);
editor.putStringSet("stringset", newset);
editor.commit();
}
public void onRestoredPreferences()
{
SharedPreferences preferences = getApplicationContext().getSharedPreferences("object", 0);
Set<String> getdataback = preferences.getStringSet("stringset", null);
arraylist.clear();
arraylist.addAll(getdataback);
}
}
公共类ListviewActivity扩展了AppCompatActivity{
arraylistdataa;
List arraylist=新建arraylist();
@凌驾
创建时受保护的void(Bundle savedInstanceState){
onRestoredPreferences();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u列表视图);
Bundle extras=getIntent().getExtras();
字符串dataExtra=extras.getString(“key”);
dataa=新的ArrayList();
dataa.addAll(arraylist);
dataa.add(dataExtra);
ListView ListView=(ListView)findViewById(R.id.ListView);
ArrayAdapter=新的ArrayAdapter(这个,android.R.layout.simple_list_item_1,android.R.id.text1,dataa);
断言listView!=null;
setAdapter(适配器);
保存数据引用(dataa);
}
公共void savedReferences(列表数据A){
SharedReferences首选项=this.getSharedReferences(“对象”,0);
SharedReferences.Editor=首选项.edit();
List arraylist=新的arraylist(dataa);
Set newset=newhashset(arraylist);
编辑器.putStringSet(“stringset”,新闻集);
commit();
}
在RestoredPreferences()上公共无效
{
SharedReferences首选项=getApplicationContext()。GetSharedReferences(“对象”,0);
Set getdataback=preferences.getStringSet(“stringset”,null);
arraylist.clear();
addAll(getdataback);
}
}
如果您想保存以备将来使用,那么最好保存在SharedReference中,或者以换行符的形式写入文件(),如果您想保存以备将来使用,那么最好保存在SharedReference中,或者以换行符的形式写入文件(),您知道,onRestoreInstanceState
和onSaveInstanceState
是实现这一目的的有效方法