android - 不能在 Activity 之间调用静态方法

Question

我正在尝试从另一个 Activity 中调用静态方法来查找分数的整数:

public class HighscoreActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.highscore);

        TextView txtGuess = (TextView) findViewById(R.id.txtScore);
        int temp = MastermindGameActivity.getScore();
        String score = Integer.toString(temp);
        txtGuess.setText(score);

    }
}

通过调用这个方法:

public static int getScore()
{
    return score;
}

为什么这行不通？我不断得到

01-14 21:28:54.347: ERROR/AndroidRuntime(1485): FATAL EXCEPTION: main 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): java.lang.RuntimeException: Unable to start activity ComponentInfo{sam.android.mastermind/sam.android.mastermind.HighscoreActivity}: java.lang.NullPointerException 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.os.Handler.dispatchMessage(Handler.java:99) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.os.Looper.loop(Looper.java:123) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.app.ActivityThread.main(ActivityThread.java:3683) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at java.lang.reflect.Method.invokeNative(Native Method) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at java.lang.reflect.Method.invoke(Method.java:507) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at dalvik.system.NativeStart.main(Native Method) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): Caused by: java.lang.NullPointerException 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at sam.android.mastermind.HighscoreActivity.blah(HighscoreActivity.java:27) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at sam.android.mastermind.HighscoreActivity.onCreate(HighscoreActivity.java:13) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 01-14 21:28:54.347: ERROR/AndroidRuntime(1485):
... 11 more

Activity 在 list 中定义。

Answer 1

试试这个..

MastermindGameActivity masterActivity = new MastermindGameActivity();

masterActivity.getScore();

您也可以尝试按照我的建议将其作为 Intent 传递。

 Intent intent=new Intent(this,Activity2.class);
 intent.putIntExtra("Score" score);

并在接收activity中拉出

 Intent sender=getIntent();
     int score = sender.getExtras().getInt("Score");