来自 getExtras() 的 NullPointerException [英] NullPointerException from getExtras()

问题描述

我正在创建将数据从一个活动传输到另一个活动的意图，如下所示:

I'm creating an intent to transfer data from one activity to another like this :

Intent intent = new Intent(this, ActivityHighScore.class);
    intent.putExtra("USERNAME", username);
    intent.putExtra("PLAYERMOVES", playerMoves);

    this.startActivity(intent);

然后我想在活动开始时检查所有这些数据是否存在，因为它可以从其他来源启动而无需设置这些数据.我使用这个语句:

Then i want to check if all of this data exists as the activity starts, as it can be started from other sources without this data being set. Im using this statement:

        Bundle bundle = getIntent().getExtras();

    if (!bundle.getString("USERNAME").equals(null) && bundle.getInt("PLAYERMOVES") != 0){
        String username = bundle.getString("USERNAME");
        int playerMoves = bundle.getInt("PLAYERMOVES");
        addHighScore(username, playerMoves);

    }   

但这会导致空指针异常，我完全确定是如何发生的.我以为我正在掌握字符串和 .equals()，但我认为它...任何帮助将不胜感激.谢谢.

But this causes a null pointerexception and I'm entirely sure how. I thought I was getting to grips with Strings and .equals(), but I think its that... Any help would be greatly appreciated. Thanks.

推荐答案

替换

Bundle bundle = getIntent().getExtras();

    if (!bundle.getString("USERNAME").equals(null) && bundle.getInt("PLAYERMOVES") != 0){
        String username = bundle.getString("USERNAME");
        int playerMoves = bundle.getInt("PLAYERMOVES");
        addHighScore(username, playerMoves);

    } 

与

 if (getIntent().getStringExtra("USERNAME") != null && (getIntent().getIntExtra("PLAYERMOVES", 0) != 0){
        String username = bundle.getString("USERNAME");
        int playerMoves = bundle.getInt("PLAYERMOVES");
        addHighScore(username, playerMoves);

  } 

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