Android Eclipse Lint API检查

Question

Thanks PT for what looks like the correct answer to question Building multi-SDK Android apps in Eclipse without losing compile-time checks . However, when I try to use the @TargetApi() annotation as recommended, it generates syntax errors.

@TargetApi(11)    // location 1
public class DisplayMessageActivity extends Activity {

    @Override
    @TargetApi(11)    // location 2
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            @TargetApi(11)    // location 3
            getActionBar().setDisplayHomeAsUpEnabled(true); }

generates two syntax errors on the @TargetApi line when it is in the middle of the code as shown at location 3:

x Syntax error, insert "enum Identifier" to complete EnumHeaderName
x Syntax error, insert "enumBody" to complete BlockStatements

The errors exist whether I have the @TargetApi line before the if statement or after it as shown. Are there any prerequisites (imports) or other considerations not mentioned in the Lint API Check article http://tools.android.com/recent/lintapicheck to get @TargetApi() working correctly?

--- Edit 9/3/2012 ---

If I move the @TargetApi annotation to before the class definition (shown as location 1) or before the method definition (shown as location 2, either before or after the @Override annotation), I get different errors:

x TargetApi cannot be resolved to a type
x The attribute value is undefined for the annotation type TargetApi

--- Edit 9/4/2012 ---

Here is the full source code:

package com.example.my.first.app;

import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class DisplayMessageActivity extends Activity {

    @TargetApi(11)
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // ActionBar introduced in Android 3.0 Honeycomb API 11
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            getActionBar().setDisplayHomeAsUpEnabled(true); }   // Up Navigation

        // Get the message from the intent
        Intent intent = getIntent();
        String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

        // Create the text view
        TextView textView = new TextView(this);
        textView.setTextSize(40);
        textView.setText(message);

        // Set the text view as the activity layout
        setContentView(textView);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_display_message, menu);
        return true;
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                NavUtils.navigateUpFromSameTask(this);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

Answer 1

FizzBuzz provided the answer to this in How do you version code in Android without compiler warnings? .

In addition to the @TargetApi(nn) annotation in the code, you also need to import the definition of that annotation:

import android.annotation.TargetApi;

For some unknown reason, an import is not required to use the @Override annotation. It would be helpful if the ADT documentation http://tools.android.com/recent/lintapicheck were fixed to eliminate the bogus code example and mention the required import.

Answer 2

The example on the website using the annotation in the middle of the code is simply wrong (or maybe outdated). The declaration of the annotation itself shows that it is only allowed for types, methods and constructors :

/** Indicates that Lint should treat this type as targeting a given API level, no matter what the
    project target is. */
@Target({TYPE, METHOD, CONSTRUCTOR})
@Retention(RetentionPolicy.CLASS)
public @interface TargetApi {
    /**
     * This sets the target api level for the type..
     */
    int value();
}

Answer 3

在覆盖注释的上方插入目标API注释