0
试图通过Android培训学习编码android应用程序。我想调整一下把东西保存到sharedPreferences中。保存和读取共享偏好不起作用
我有一个活动,当你按下一个按钮,运行这段代码
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();
}
,并在显示时运行该代码的另一项活动。
public String getMessage(){
SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);
String message = sharedPref.getString("message","default");
return message;
}
这两个方法应该保存/读取一些数据。我真的不知道我做错了什么。
类的整个代码:
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;
}
}
尝试代替使用'SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(本);' –