怎样从一个类中获取整型值并在另一个类中使用它

huangapple
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英文:

how to take int value from a class and use it in another one

问题

  1. public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
  2.     switch (position) {
  3.         case 0:
  4.             Intent i = new Intent(MainActivity.this, TabActivity.class);
  5.             startActivity(i);
  6.             Position = 0;
  7.             break;
  8.         case 1:
  9.             i = new Intent(MainActivity.this, TabActivity.class);
  10.             startActivity(i);
  11.             Position = 1;
  12.             break;
  13.         case 2:
  14.             i = new Intent(MainActivity.this, TabActivity.class);
  15.             startActivity(i);
  16.             Position = 2;
  17.             break;
  18.         case 3:
  19.             i = new Intent(MainActivity.this, TabActivity.class);
  20.             startActivity(i);
  21.             Position = 3;
  22.             break;
  23.         case 4:
  24.             i = new Intent(MainActivity.this, TabActivity.class);
  25.             startActivity(i);
  26.             Position = 4;
  27.             break;
  28.     }
  29. }
  30. });
  32. and use it in a different Fragment class in a switch loop
  34. @Override
  35. public View onCreateView(LayoutInflater inflater, ViewGroup container,
  36.                          Bundle savedInstanceState) {
  38.     View rootView = inflater.inflate(R.layout.activity_city, container, false);
  40.     int position = new MainActivity().Position;
  42.     ArrayList<CityScreenItem> city = new ArrayList<>();
  44.     switch (position) {
  45.         case 0:
  46.             city.add(new CityScreenItem("Giza", "Giza is good",
  47.                     R.drawable.dubai));
  48.             break;
  49.         case 1:
  50.             city.add(new CityScreenItem("Dubai", "Dubai is good",
  51.                     R.drawable.egypt));
  52.             break;
  53.     }
  55.     CityScreenAdapter adapter = new CityScreenAdapter(getActivity(), city);
  56.     ListView listView = rootView.findViewById(R.id.list);
  57.     listView.setAdapter(adapter);
  59.     return rootView;
  60. }

但是每次都显示第一个 case，经过检查发现是由于 int position = new MainActivity().Position; 这行代码导致的，但我找不到答案。
注意
我在类开始时确实声明了一个名为 Position 的 public int 变量。

英文:

I need to get the position of the grid view in the onItemClick

  1. public void onItemClick(AdapterView&lt;?&gt; parent, View v,
  2. int position, long id) {
  3. switch (position) {
  4. case 0:
  5. Intent i = new Intent(MainActivity.this, TabActivity.class);
  6. startActivity(i);
  7. Position = 0;
  8. break;
  9. case 1:
  10. i = new Intent(MainActivity.this, TabActivity.class);
  11. startActivity(i);
  12. Position = 1;
  13. break;
  14. case 2:
  15. i = new Intent(MainActivity.this, TabActivity.class);
  16. startActivity(i);
  17. Position = 2;
  18. break;
  19. case 3:
  20. i = new Intent(MainActivity.this, TabActivity.class);
  21. startActivity(i);
  22. Position = 3;
  23. break;
  24. case 4:
  25. i = new Intent(MainActivity.this, TabActivity.class);
  26. startActivity(i);
  27. Position = 4;
  28. break;
  29. }
  30. }
  31. });

and use it in a different Fragment class in a switch loop

  1.   @Override
  2. public View onCreateView(LayoutInflater inflater, ViewGroup container,
  3. Bundle savedInstanceState) {
  4. View rootView = inflater.inflate(R.layout.activity_city, container, false);
  5. int position = new MainActivity().Position;
  6. ArrayList&lt;CityScreenItem&gt; city = new ArrayList&lt;&gt;();
  7. switch (position) {
  8. case 0:
  9. city.add(new CityScreenItem(&quot;Giza&quot;, &quot;Giza is good&quot;,
  10. R.drawable.dubai));
  11. break;
  12. case 1:
  13. city.add(new CityScreenItem(&quot;Dubai&quot;, &quot;Dubai is good&quot;,
  14. R.drawable.egypt));
  15. break;
  16. }
  17. CityScreenAdapter adapter = new CityScreenAdapter(getActivity(), city);
  18. ListView listView = rootView.findViewById(R.id.list);
  19. listView.setAdapter(adapter);
  20. return rootView;
  21. }

but it always displays the first case when I check this was due to the int position = new MainActivity().Position;code but I could not find the answer.
Note
I did make a public int for Position at the beginning of the class

答案1

得分: 0

你每次都在创建一个新的对象：

  1. int position = new MainActivity().Position;

这将会将位置重置为你所设置的值。将Position设置为静态。

  1. public static int POSITION = 0;

这应该能解决你的问题。像下面这样访问它：

  1. int position = MainActivity.POSITION;
英文:

You are creating a new object every time:

  1. int position = new MainActivity().Position;

This will reset the position to what you are setting it to. Make Position static.

  1. public static int POSITION = 0;

This should fix your problem. Access it like below:

  1. int position = MainActivity.POSITION;

huangapple
  • 本文由 发表于 2020年7月26日 09:52:09
  • 转载请务必保留本文链接：https://go.coder-hub.com/63095349.html
  • android
  • class
  • gridview
  • java
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