0
試圖通過Android培訓學習編碼android應用程序。我想調整一下把東西保存到sharedPreferences中。保存和讀取共享偏好不起作用
我有一個活動,當你按下一個按鈕,運行這段代碼
public void saveMessage(String message){
//Save message local
SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("message",message);
editor.commit();
}
,並在顯示時運行該代碼的另一項活動。
public String getMessage(){
SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);
String message = sharedPref.getString("message","default");
return message;
}
這兩個方法應該保存/讀取一些數據。我真的不知道我做錯了什麼。
類的整個代碼:
MainActivity.java
package com.example.myfirstapp;
import ...;
public class MainActivity extends AppCompatActivity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
/** Called when the User clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
saveMessage(message);
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
public void saveMessage(String message){
//Save message local
SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("message",message);
editor.commit();
}
}
DisplayMessageActivity.java
package com.example.myfirstapp;
import ...;
public class DisplayMessageActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
message = getMessage();
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
ViewGroup layout = (ViewGroup) findViewById(R.id.activity_display_message);
layout.addView(textView);
}
public String getMessage(){
SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);
String message = sharedPref.getString("message","default");
return message;
}
}
嘗試代替使用'SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(本);' –