Android Spinner:在初始化期间避免onItemSelected调用

Question

我用a Spinner和a 创建了Android应用程序TextView.我的任务是在TextView的Spinner下拉列表中显示所选项目.我在onCreate方法中实现了Spinner,所以当我运行程序时,它会显示一个值TextView(在从下拉列表中选择一个项目之前).

我只想在从下拉列表中选择一个项目后才在TextView中显示该值.我该怎么做呢？

这是我的代码:

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;

public class GPACal01Activity extends Activity implements OnItemSelectedListener {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Spinner spinner = (Spinner) findViewById(R.id.noOfSubjects);

        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,R.array.noofsubjects_array, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);
    }

    public void onItemSelected(AdapterView<?> parent, View arg1, int pos,long id) {
        TextView textView = (TextView) findViewById(R.id.textView1);
        String str = (String) parent.getItemAtPosition(pos);
        textView.setText(str);
    }

    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }
}

Answer 1

spinner.setOnItemSelectedListener(this); // Will call onItemSelected() Listener.

所以第一次用任何Integer值处理它

示例:最初采取 int check = 0;

public void onItemSelected(AdapterView<?> parent, View arg1, int pos,long id) {
   if(++check > 1) {
      TextView textView = (TextView) findViewById(R.id.textView1);
      String str = (String) parent.getItemAtPosition(pos);
      textView.setText(str);
   }
}

您可以使用布尔值以及检查当前位置和先前位置来执行此操作.看这里

Answer 2

只需在设置OnItemSelectedListener之前放置此行

spinner.setSelection(0,false)

Answer 3

从API级别3开始,您可以在具有布尔值的Activity上使用onUserInteraction()来确定用户是否正在与设备进行交互.

http://developer.android.com/reference/android/app/Activity.html#onUserInteraction()

@Override
public void onUserInteraction() {
     super.onUserInteraction();
     userIsInteracting = true;
}

作为活动的一个领域,我有:

 private boolean userIsInteracting;

最后,我的微调器:

      mSpinnerView.setOnItemSelectedListener(new OnItemSelectedListener() {

           @Override
           public void onItemSelected(AdapterView<?> arg0, View view, int position, long arg3) {
                spinnerAdapter.setmPreviousSelectedIndex(position);
                if (userIsInteracting) {
                     updateGUI();
                }
           }

           @Override
           public void onNothingSelected(AdapterView<?> arg0) {

           }
      });

当你来完成活动时,布尔值会重置为false.奇迹般有效.

Answer 4

这对我有用

Spinner在Android中的初始化是有问题的,有时上述问题通过这种模式解决了.

Spinner.setAdapter();
Spinner.setSelected(false);  // must
Spinner.setSelection(0,true);  //must
Spinner.setonItemSelectedListener(this);

设置适配器应该是第一部分,onItemSelectedListener(this)在初始化微调器时将是最后一个.通过上面的模式,在初始化微调器期间不会调用我的OnItemSelected()

Answer 5

避免在初始化期间调用 spinner.setOnItemSelectedListener()

spinner.setSelection(Adapter.NO_SELECTION, true); //Add this line before setting listener
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
});

Answer 6

哈哈......我有同样的问题.当initViews()只是这样做时.序列是关键,监听器是最后一个.祝好运 !

spinner.setAdapter(adapter);
spinner.setSelection(position);
spinner.setOnItemSelectedListener(listener);

Answer 7

我的解决方案

protected boolean inhibit_spinner = true;


@Override
        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int pos, long arg3) {

            if (inhibit_spinner) {
                inhibit_spinner = false;
            }else {

            if (getDataTask != null) getDataTask.cancel(true);
            updateData();
            }

        }

Answer 8

你可以通过这种方式做到这一点:

AdapterView.OnItemSelectedListener listener = new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
            //set the text of TextView
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });

yourSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
            yourSpinner.setOnItemSelectedListener(listener);
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });

首先,我创建一个监听器并归因于一个变量回调; 然后我创建第二个匿名监听器,当第一次调用它时,这会改变监听器=]

Answer 9

然后，可以在 onTouch 方法中将用户交互标志设置为 true，并在onItemSelected()处理选择更改后重置。我更喜欢这个解决方案，因为用户交互标志是专门为微调器处理的，而不是为活动中可能影响所需行为的其他视图处理的。

在代码中：

为微调器创建监听器：

public class SpinnerInteractionListener implements AdapterView.OnItemSelectedListener, View.OnTouchListener {

    boolean userSelect = false;

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        userSelect = true;
        return false;
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
        if (userSelect) { 
            userSelect = false;
            // Your selection handling code here
        }
    }

}

将侦听器添加到微调器中，同时作为 anOnItemSelectedListener和 an OnTouchListener：

SpinnerInteractionListener listener = new SpinnerInteractionListener();
mSpinnerView.setOnTouchListener(listener);
mSpinnerView.setOnItemSelectedListener(listener);