[英]Shared Preferences Android Studio
對於下面的代碼,我試圖檢索共享首選項,我認為它保存正確,但是當我返回登錄屏幕時,所有數據都消失了。 當我回到這個屏幕時,我需要它保留下來。 所以我在個人資料頁面上的三個單獨的行中輸入姓名、年齡和 ID。 然后我按下保存按鈕然后按下操作欄上的返回到之前的頁面。 當我回到個人資料頁面時,我的信息應該仍然存在,但沒有任何幫助?
package com.example.myprofile;
import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import java.sql.Savepoint;
public class Profile extends AppCompatActivity {
protected EditText NameEditText;
protected EditText AgeEditText;
protected EditText IDEditText;
protected Button saveButton;
protected Button settings_id;
String name;
String age;
String id;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profile);
EditText mEdit = (EditText) findViewById(R.id.NameEditText);
mEdit.setEnabled(false);
EditText mEdit1 = (EditText) findViewById(R.id.AgeEditText);
mEdit1.setEnabled(false);
EditText mEdit2 = (EditText) findViewById(R.id.IDEditText);
mEdit2.setEnabled(false);
NameEditText = (EditText) findViewById(R.id.NameEditText);
AgeEditText = (EditText) findViewById(R.id.AgeEditText);
IDEditText = (EditText) findViewById(R.id.IDEditText);
settings_id = (Button) findViewById(R.id.settings_id);
saveButton = (Button) findViewById(R.id.SaveButton);
SharedPreferences prefs = getSharedPreferences(getString(R.string.ProfileName), Context.MODE_PRIVATE);
name = prefs.getString("userName", "");
age = prefs.getString("userAge", "");
id = prefs.getString("userID", "");
saveButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String name = NameEditText.getText().toString();
String age = AgeEditText.getText().toString();
String id = IDEditText.getText().toString();
SharedPreferences sharedPreferences = getSharedPreferences(getString(R.string.ProfileName), Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString(getString(R.string.ProfileName), name);
editor.putString(getString(R.string.ProfileAge), age);
editor.putString(getString(R.string.ProfileID), id);
editor.apply();
if (Integer.parseInt(age) < 18)
{
Toast toast1 = Toast.makeText(getApplicationContext(), "Invalid Age", Toast.LENGTH_LONG);
toast1.show();
}
else if (!name.isEmpty() && !age.isEmpty() && !id.isEmpty())
{
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
Toast toast = Toast.makeText(getApplicationContext(), "Name Saved!", Toast.LENGTH_LONG);
toast.show();
}
else
{
Toast toast2 = Toast.makeText(getApplicationContext(), "Incomplete Info", Toast.LENGTH_LONG);
toast2.show();
}
}
});
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.settings_id:
{
EditText mEdit = (EditText) findViewById(R.id.NameEditText);
mEdit.setEnabled(true);
EditText mEdit1 = (EditText) findViewById(R.id.AgeEditText);
mEdit1.setEnabled(true);
EditText mEdit2 = (EditText) findViewById(R.id.IDEditText);
mEdit2.setEnabled(true);
saveButton.setEnabled(Boolean.parseBoolean("True"));
}
default:
return super.onOptionsItemSelected(item);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu, menu);
return true;
}
}
要保存數據,請使用以下代碼示例
name = NameEditText.getText().toString();
age = AgeEditText.getText().toString();
id = IDEditText.getText().toString();
SharedPreferences prefs = getSharedPreferences(
"com.example.myprofile", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = prefs.edit();
editor.putString("userName", name);
editor.putString("userAge", age);
editor.putString("userID", id);
editor.apply();
要檢索數據,請使用以下代碼示例
SharedPreferences prefs = getSharedPreferences(
"com.example.myprofile", Context.MODE_PRIVATE);
name = prefs.getString("userName", "");
age = prefs.getString("userAge", "");
id = prefs.getString("userID", "");
在onCreate
方法之前
String name;
String age;
String id;
解釋:
getSharedPreferences
的第一個參數是你的包名,基本上是你代碼中的第一行。SharedPreferences
實例,一個就夠了SharedPreferences.Editor
實例,一個也足夠了。key
,例如用於保存數據的用戶名,因為您隨后需要通過意圖將密鑰傳遞給其他活動,如果您打算這樣做,為什么不發送用戶名而不是鑰匙?editor.apply()
而不是editor.commit()
onPause()
保存數據並在onResume()
檢索它是很常見的,因此將它們聲明為全局是有用的,以避免編寫額外的代碼行。嘗試(在行尾應用()):
editor.putString(getString(R.string.ProfileName), name).apply();
editor1.putString(getString(R.string.ProfileAge), age).apply();
editor2.putString(getString(R.string.ProfileID), id).apply();
您正在使用特定字符串( getString(R.string.ProfileAge) ....)通過使用 commit() 或 apply() 在私有模式下將數據保存在共享首選項中:-
SharedPreferences sharedPreferences1 = getSharedPreferences(getString(R.string.ProfileAge), Context.MODE_PRIVATE);
SharedPreferences sharedPreferences2 = getSharedPreferences(getString(R.string.ProfileID), Context.MODE_PRIVATE);
但是您並不是要在必須使用的私有模式下使用這些字符串來獲取該數據:-
SharedPreferences sharedPref = getSharedPreferences(getString(R.string.ProfileAge), Context.MODE_PRIVATE);
String name = sharedPref.getString("key", "defaultValue");
為了保存
SharedPreferences pref = getSharedPreferences("Name", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putBoolean("keyname",true);
editor.putString("keyname","string value");
editor.putInt("keyname","int value");
editor.putFloat("keyname","float value");
editor.putLong("keyname","long value");
editor.commit();
忘記
SharedPreferences pref = getSharedPreferences("Name", Context.MODE_PRIVATE);
pref.getString("keyname",null);
pref.getInt("keyname",0);
pref.getFloat("keyname",0);
pref.getBoolean("keyname",true);
pref.getLong("keyname",0);
對於單個刪除
SharedPreferences pref = getSharedPreferences("Name", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.remove("keyname");
editor.commit();
對於所有刪除
SharedPreferences pref = getSharedPreferences("Name", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.clear();
editor.commit();
您可以像這樣使用共享偏好
優先保存數據
SharedPreferences share = getSharedPreferences("Data", Context.MODE_PRIVATE);
SharedPreferences.Editor edit = share.edit();
edit.putLong("user_id", 1);
edit.putString("token","1243434sfdfsf");
edit.commit();
從偏好中獲取數據
SharedPreferences share = getSharedPreferences("Data", Context.MODE_PRIVATE);
share.getLong("user_id", 0);
share.getString("token", "");
您可以嘗試此鏈接以獲取更多詳細信息: Android 中的共享首選項
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