顯示對話框取決於ViewPager狀態

Question

我有一個ViewPager，並讓想象，我是第0頁

我有這個頁面上的一個按鈕上，並單擊此按鈕，我想顯示一個對話框，並將頁面切換到頁面1.

當我的頁面更改爲頁面1時，我希望對話框消失。

當我做到了，我沒有看到對話框，當頁面被更改時它出現並消失，但我確信，我在這些操作之間有1000毫秒的延遲。

請幫忙，我該如何顯示對話框？

package com.example.ViewPagerDialog; 

import android.app.Activity; 
import android.app.ProgressDialog; 
import android.content.Context; 
import android.os.Bundle; 
import android.support.v4.view.PagerAdapter; 
import android.support.v4.view.ViewPager; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Button; 
import android.widget.TextView; 

public class MyActivity extends Activity { 
    private int currentPage; 

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

     final MyViewPager viewPager = (MyViewPager) findViewById(R.id.view_pager); 
     final Button leftSwitcher = (Button) findViewById(R.id.left_switcher); 
     final Button rightSwitcher = (Button) findViewById(R.id.right_switcher); 
     final ProgressDialog progressDialog = new ProgressDialog(this); 

     leftSwitcher.setVisibility(View.GONE); 
     progressDialog.setTitle("Wait..."); 

     viewPager.setAdapter(new MyPagerAdapter(this)); 
     viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { 
      public void onPageScrolled(int i, float v, int i2) { 

      } 

      public void onPageSelected(int i) { 
       progressDialog.dismiss(); 

       currentPage = i; 

       if (i == 0) { 
        leftSwitcher.setVisibility(View.GONE); 
       } else if (i == 1) { 
        leftSwitcher.setVisibility(View.VISIBLE); 
        rightSwitcher.setVisibility(View.VISIBLE); 
       } else if (i == 2) { 
        rightSwitcher.setVisibility(View.GONE); 
       } 
      } 

      public void onPageScrollStateChanged(int i) { 

      } 
     }); 

     leftSwitcher.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View view) { 
       progressDialog.show(); 
       sleepThread(); 
       viewPager.setCurrentItem(currentPage - 1); 
      } 
     }); 

     rightSwitcher.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View view) { 
       progressDialog.show(); 
       sleepThread(); 
       viewPager.setCurrentItem(currentPage + 1); 
      } 
     }); 
    } 

    private void sleepThread() { 
     try { 
      Thread.sleep(1000); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
    } 

    private class MyPagerAdapter extends PagerAdapter { 
     View[] views = new View[3]; 

     public MyPagerAdapter(Context context) { 
      TextView view1 = new TextView(context); 
      TextView view2 = new TextView(context); 
      TextView view3 = new TextView(context); 

      view1.setText("View 1"); 
      view2.setText("View 2"); 
      view3.setText("View 3"); 

      views[0] = view1; 
      views[1] = view2; 
      views[2] = view3; 
     } 

     @Override 
     public int getCount() { 
      return views.length; 
     } 

     @Override 
     public boolean isViewFromObject(View view, Object o) { 
      return (view.equals(o)); 
     } 

     @Override 
     public Object instantiateItem(ViewGroup collection, int position) { 
      collection.addView(views[position]); 
      return views[position]; 
     } 

     @Override 
     public void destroyItem(android.view.ViewGroup container, int position, java.lang.Object object) { 
      container.removeView(views[position]); 
     } 
    } 
} 

Answer 1

首先，不要像你那樣用Thread.sleep()阻止UI線程。通過使用Thread.sleep()，您將基本上設置對話框的顯示命令（在從onCLick()方法返回後將發生），睡眠一秒（並且您的應用將凍結），然後設置頁面在ViewPager上，這將觸發聽衆，解散對話。相反，您可以使用Handler至

private Handler mHandler = new Handler(); 

// in the onClick method 
progressDialog.show(); 
mHandler.postDelayed(new Runnable() { 

    @Override 
    public void run() { 
     viewPager.setCurrentItem(currentPage - 1); 
    } 

}, 1000);