intent.getIntent（）.getExtras（）中的nullpoInterException（）

发布于 2025-02-13 04:09:16 字数 1469 浏览 2 评论 0原文

我正在使用意图将名称（arrayList）从一个活动传递到另一个活动。
我在第二个活动的ongreate（）方法中称为getIntent（）方法。
是否想在我自己的函数中使用传递的名称（arrayList），但它是


   protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           Intent intent = getIntent();
   
           Bundle bundle = intent.getExtras();
           ArrayList<String> namesList = bundle.getStringArrayList("names");
   }

是否想在此中使用名称：


    public class game_main extends AppCompatActivity {
        TextView playerNameHolder;
        .........................
        .........................
        .........................
        Intent intent = getIntent();
        Bundle bundle = intent.getExtras();
        ArrayList<String> namesList = bundle.getStringArrayList("names");
        ........................
        ........................
        ........................
        public void gameReset(View view) {
        ........................
        ........................
        TextView playerNameHolder = (TextView) findViewById(R.id.turn_status);
        playerNameHolder.setText(namesList.get(0) + "'s turn");
        }
    }

nameList.get（0）不包括捆绑行代码，但是当包括时，它给出了null指针异常

java.lang.nullpointerexception：尝试调用虚拟方法'android.os.bundle android.content.intent.getExtras（）'null对象引用

原文

I am using Intent to pass names(ArrayList) from one activity to another.
I called the getIntent() method in the second activity's onCreate() method.
want to use passed names(ArrayList) inside my own functions but it is out of scope


   protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           Intent intent = getIntent();
   
           Bundle bundle = intent.getExtras();
           ArrayList<String> namesList = bundle.getStringArrayList("names");
   }

Want to use names in this:


    public class game_main extends AppCompatActivity {
        TextView playerNameHolder;
        .........................
        .........................
        .........................
        Intent intent = getIntent();
        Bundle bundle = intent.getExtras();
        ArrayList<String> namesList = bundle.getStringArrayList("names");
        ........................
        ........................
        ........................
        public void gameReset(View view) {
        ........................
        ........................
        TextView playerNameHolder = (TextView) findViewById(R.id.turn_status);
        playerNameHolder.setText(namesList.get(0) + "'s turn");
        }
    }

namesList.get(0) is out of scope when Bundle line code is not included, but when included it gives NULL POINTER EXCEPTION

java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null object reference

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风筝在阴天搁浅。 2025-02-20 04:09:16

请勿在AppCompatactivity上调用方法（或超级类），例如您在第二个代码shippet中使用intent = getIntent（）; 。

您需要将两种方法组合在一起：将名称清单作为字段，并在increate（）中初始化它：

public class game_main extends AppCompatActivity {
   ArrayList<String> namesList;

   protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           Intent intent = getIntent();
   
           Bundle bundle = intent.getExtras();
           
           namesList = bundle.getStringArrayList("names");
   }
}

Do not call methods on AppCompatActivity (or superclasses) from field initializers, such as you are doing with Intent intent = getIntent(); in your second code snippet.

You need to combine your two approaches: putting namesList as a field and initializing it in onCreate():

public class game_main extends AppCompatActivity {
   ArrayList<String> namesList;

   protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           Intent intent = getIntent();
   
           Bundle bundle = intent.getExtras();
           
           namesList = bundle.getStringArrayList("names");
   }
}

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