android - int countervalue = i.getIntExtra ("Count", 0);使应用程序崩溃

Question

    int countervalue = i.getIntExtra("Count", 10);

我在不同的 Activity 中有这行代码，当有人点击按钮时，他们会转到该 Activity 。如果没有这行代码，应用程序将完美运行。

这是 Activity 的完整代码:

  package com.example.navjeevenmann.mytycoon;

  import android.content.Intent;
  import android.os.Bundle;
  import android.support.v7.app.AppCompatActivity;
  import android.view.View;
  import android.widget.AdapterView;
  import android.widget.ArrayAdapter;
  import android.widget.ListView;

public class SecondActivity extends AppCompatActivity {
private ListView listView;
Intent i = getIntent();
int userchoice;
@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);
    int countervalue = i.getIntExtra("Count", 0);
    String[] values = {"Apple($20)-                Generates $40/sec", 
    "Second", "Third"};
    listView = (ListView) findViewById(R.id.List);
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_expandable_list_item_1, android.R.id.text1, values);
    listView.setAdapter(adapter);

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {


        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {


        }

    });


}
}

Answer 1

在 onCreate() 方法中初始化 i = getIntent();

就在 int countervalue = i.getIntExtra("Count", 0); 之前