将选定的值传递给另一个类 Android

Question

我正在尝试将从微调器中选择的值传递给另一个类，但它传递了 null。

protected int secondsToUse;

final String titles[] = {
  "1 Second","2 Seconds", "3 Seconds","4 Seconds",
  "5 Seconds","6 Seconds","7 Seconds","8 Seconds","9 Seconds","10 Seconds"
};

mSeconds = (Spinner) view.findViewById(R.id.secondsSpinner);

 ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_spinner_item, titles);
        arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    mSeconds.setAdapter(arrayAdapter);
mSeconds.setOnItemSelectedListener(
    new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
            // secondsToUse is declared a as int variable above
            secondsToUse = position + 1;
        }



// passing the value to another class.// PASSES AS NULL
Intent recipientsIntent = new Intent(getActivity(), RecipientsActivity.class);
                    recipientsIntent.putExtra("key1", secondsToUse);
                    startActivity(recipientsIntent);

// retrieving the value //retrieves as null
String Seconds = getIntent().getStringExtra("key1");
byte[] secs = Seconds.getBytes();

我正在尝试获取用户在微调器上选择的位置，以便我可以将其传递给计时器以使图像自毁。此刻我为空

Answer 1

编辑：我忘了考虑 getIntExtra() 在我的第一个答案中采用 两个 参数。它需要一个识别“键”和一个默认值。

要检索RecipientsActivity 中选定行的位置，请保持您的代码不变。然后，在onCreate() 的RecipientsActivity 中：

int seconds = getIntent().getIntExtra("key1", -1);

---

Answer 2

你为什么使用getStringExtra()？

你传递一个整数，所以接收一个整数

// retrieving the value
int seconds = getIntent().getIntExtra("key1");

如果你需要它作为字符串使用

String secondsAsString = String.valueOf(seconds);

Answer 3

在 OnItemSelectListner 中使用 Explicit Intent 调用您的下一个 Activity 试试这个

mSeconds.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

@Override

public void onItemSelected(AdapterView parentView, View selectedItemView, int

位置，长 id) {

               secondToUse = String.valueOf(position + 1);
               Intent intent = new Intent(CurrentClass.this,NewClass.Class);
               putInentExtra("Key1","secondTouse");
               startActivity(intent);

        }

然后在你的下一个活动中获得 Intent By-

意图 i= getIntent();

String getPosition= i.getStringExtra("Key1");

享受:)

Answer 4

将getStringExtra() 替换为getIntExtra()

int default = -1;
String val = getIntent().getIntExtra("key1",default);
if(val == default){
  //Log, exception, no value etc.
}
String Seconds = String.valueOf(val);
byte[] secs = Seconds.getBytes();

当从ListView中选择元素时调用开始Activity

mSeconds.setOnItemSelectedListener(
    new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
            // secondsToUse is declared a as int variable above
            secondsToUse = position + 1;
            // passing the value to another class.// PASSES AS NULL
            Intent recipientsIntent = new Intent(getActivity(),     RecipientsActivity.class);
            recipientsIntent.putExtra("key1", secondsToUse);
            startActivity(recipientsIntent);
        }

Answer 5

只需将getStringExtra() 替换为getIntExtra()

int defaultSecond = -1;
int seconds = getIntent().getIntExtra("key1",defaultSecond);

原因：因为您在putExtra("key1", secondsToUse); 中放入了int 而不是String

另外，在命名变量时使用驼峰式大小写。使用秒而不是秒。 我希望这会有所帮助！