java - Android Java - 共享首选项编辑器问题

Question

我正在尝试将 3 个不同字符串的值永久存储到共享首选项中。这些字符串肯定包含我通过在 textView 中设置字符串来测试它们的值。

public class verified extends Activity{

    SharedPreferences sharedpreferences;
    TextView textView100;
     String MyPREFERENCES = "MyPreferences" ;

        String NString;
        String MString;
        String EAString;

           public static final String MVerified = "";
           public static final String NVerified = "";
           public static final String EAVerified = "";



    public void onCreate(Bundle savedInstanceState)

     {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.verified);

  sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);

         Bundle bundle = getIntent().getExtras();
         NString = bundle.getString("NString");
     MString = bundle.getString("MString");
     EAString = bundle.getString("EAString");

      textView100 = (TextView) findViewById(R.id.textView100);

    textView100.setText(MString + " , " + NString + " , " + EAString);


        Button VCompleteButton = (Button) findViewById(R.id.VCompleteButton);

        VCompleteButton.setOnClickListener(new View.OnClickListener()

        {
           public void onClick(View view) 
           {    



             Editor editor = sharedpreferences.edit();
             editor.putString(MVerified, MString);
             editor.putString(NVerified, NString);
             editor.putString(EAVerified, EAString);
             editor.commit(); 


           }



           });


 }



}

但是现在的问题是 EAString 将其值存储在所有三个中。共享首选项。当我在主要 Activity 上执行此操作时。它向我显示了 EAStrin 3 次。

textView2.setText((sharedpreferences.getString(MobileVerified, "")) + " , "+ (sharedpreferences.getString(NameVerified, "")) +  " , "+ (sharedpreferences.getString(EmailAddressVerified, "")));

Answer 1

您从未启动sharedpreferences:

SharedPreferences sharedpreferences;

这就是你在这里得到 NullPointerException 的原因:

Editor editor = sharedpreferences.edit();

在使用 SharedPreferences 之前，在 onCreate 方法中添加类似的内容:

sharedpreferences = this.getSharedPreferences(
  "com.example.app", Context.MODE_PRIVATE);

这是你的 key :

public static final String MVerified = "";
           public static final String NVerified = "";
           public static final String EAVerified = "";

每个键都是一个空字符串。您必须为 SharedPreferences 中的每个条目定义一个键:

public static final String MVerified = "key1";
           public static final String NVerified = "key2";
           public static final String EAVerified = "key3";

否则您将用下一个条目覆盖每个条目...