SharedPreferences返回一个空字符串

Question

Why does the toast only show an empty string or whatever I input as the "default" value on the getString line

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    SharedPreferences sharedPreferences = this.getSharedPreferences("com.example.stefan.dijeljenepreference", Context.MODE_PRIVATE);
    sharedPreferences.edit().putString("username", "stefan");

    String username = sharedPreferences.getString("username","");
    Toast.makeText(this,"username:" + username, Toast.LENGTH_SHORT).show();
}

Answer 1

您应该使用如下的apply（）方法保存所做的编辑

sharedPreferences.edit().putString("username", "stefan").apply();