Android：初始化变量为已设偏好时遇非静态方法静态上下文引用错误求助

Hey there! Let's break down this error and get your code working right away.

What the Error Means #

That error message is telling you two key things:

1. You're trying to call a non-static method (a method that belongs to an instance of a class, not the class itself)
2. You're doing this from a static context (like a static variable declaration, static method, or static initializer block)

Static code belongs to the class as a whole, not to any specific object instance of that class. Non-static methods need an actual object instance to run—so you can't call them without first creating or accessing that instance.

Why Your Code Is Triggering This #

Your line private int mShuffleMode = SharedPreferences.getInt("shufflemode"); has two issues:

1. getInt() is not a static method of the SharedPreferences class. It's a method that belongs to a specific instance of SharedPreferences (you have to create or retrieve that instance first).
2. If you're declaring mShuffleMode as a static variable (or initializing it in a static block), you're working in a static context where you can't access non-static methods like the instance-based getInt().

Step-by-Step Fix #

Here's how to fix this properly:

1. First, Get a SharedPreferences Instance #

You can't call getInt() directly on the SharedPreferences class. Instead, you need to retrieve an instance using your app's Context:

• In an Activity or Fragment: Use getSharedPreferences() (specify your preferences file name and mode)
• In other classes: Pass a Context (use the Application Context to avoid memory leaks)

2. Initialize Your Variable in a Non-Static Context #

Avoid initializing variables that depend on Context (like SharedPreferences) in static declarations. Instead, initialize them in a lifecycle method (like onCreate() for Activities) or an instance method.

Example Working Code #

Here's how it should look in an Activity:

// Declare your variable (non-static, unless you have a specific reason to make it static)
private int mShuffleMode;

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

    // Get the SharedPreferences instance
    SharedPreferences prefs = getSharedPreferences("your_preferences_file_name", MODE_PRIVATE);
    
    // Retrieve the value—note the second parameter is a default value (required!)
    mShuffleMode = prefs.getInt("shufflemode", 0); // Use 0 or your preferred default mode
}

If You Need Static Access (Use Carefully!) #

If you absolutely need to get this value from a static method, pass a Context (use Application Context to prevent leaks):

public static int getShuffleMode(Context context) {
    SharedPreferences prefs = context.getApplicationContext()
        .getSharedPreferences("your_preferences_file_name", MODE_PRIVATE);
    return prefs.getInt("shufflemode", 0);
}

Key Notes #

• Always include a default value in getInt()—this ensures your app doesn't crash if the "shufflemode" key doesn't exist yet.
• Avoid storing Context references in static fields—it's a common cause of memory leaks. Use the Application Context if you need static access.

内容的提问来源于stack exchange，提问作者Brandon Nolet