可以以编程方式打开Android应用一个微调？ [英] Possible to programmatically open a Spinner in Android app?

问题描述

如果你有一个手柄，在Android 活动 A 微调的对象，可以以编程方式弹出打开微调选项​​ - 从而迫使用户选择的选项，即使他们没有点击微调自己？

If you have a handle to a Spinner object in an Android activity, can you programmatically pop open the spinner options - thereby forcing the user to choose an option even though they did not click on the spinner themselves?

推荐答案

要打开微调你只需要调用它的<一个href="http://developer.android.com/reference/android/widget/Spinner.html#performClick%28%29">performClick()方法。

To open the Spinner you just need to call it's performClick() method.

请记住，你只能叫从UI线程此方法。如果你需要从一个单独的线程打开微调应该创建一个处理器在UI线程然后，从你的第二个线程，发送调用performClick（）来处理程序可运行的对象。

Keep in mind that you may only call this method from the UI thread. If you need to open the Spinner from a separate thread you should create a Handler in the UI thread and then, from your second thread, send a runnable object that calls performClick() to the Handler.

package com.example.SpinnerDemo;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.os.Handler;

public class SpinnerDemo extends Activity {

    private Handler h;
    private Spinner s;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        h = new Handler();

        s = (Spinner) findViewById(R.id.spinner);
        ArrayAdapter adapter = ArrayAdapter.createFromResource(this,
                R.array.planets, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(
                android.R.layout.simple_spinner_dropdown_item);
        s.setAdapter(adapter);

        // Open the Spinner...
        s.performClick();

        // Spawn a thread that triggers the Spinner to open after 5 seconds...
        new Thread(new Runnable() {
            public void run() {
                // DO NOT ATTEMPT TO DIRECTLY UPDATE THE UI HERE, IT WON'T WORK!
                // YOU MUST POST THE WORK TO THE UI THREAD'S HANDLER
                h.postDelayed(new Runnable() {
                    public void run() {
                        // Open the Spinner...
                        s.performClick();
                    }
                }, 5000);
            }
        }).start();
    }
}

用这个例子中的资源可以在这里找到。

The resources used by this example can be found here.

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