居中進度編程中的Android

Question

我試圖居中ProgressBar編程方式使用下列內容：

ViewGroup layout = (ViewGroup) findViewById(android.R.id.content).getRootView(); 
progressBar = newProgressBar(SignInActivity.this,null,android.R.attr.progressBarStyleLarge); 
progressBar.setIndeterminate(true); 
progressBar.setVisibility(View.VISIBLE); 
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(100,100); 
params.addRule(RelativeLayout.CENTER_IN_PARENT); 
layout.addView(progressBar,params); 

的大小設置似乎工作正常，但ProgressBar不會在現有佈局中心（由定義XML與相對佈局）。這裏有什麼明顯的錯誤嗎？

的XML如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
tools:context=".test" 
android:typeface="monospace"> 

</RelativeLayout> 

即它只是一個空的相對佈局，以測試與，看看我能得到它以編程方式添加一個進度條。

謝謝。

Answer 1

如果你想以編程方式做到這一點，你可以像下面：

RelativeLayout layout = new RelativeLayout(this); 
progressBar = new ProgressBar(SignInActivity.this,null,android.R.attr.progressBarStyleLarge); 
progressBar.setIndeterminate(true); 
progressBar.setVisibility(View.VISIBLE); 
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(100,100); 
params.addRule(RelativeLayout.CENTER_IN_PARENT); 
layout.addView(progressBar,params); 

setContentView(layout); 

Answer 2

使用您的編碼，這種風格，這給你想要的結果。

ViewGroup layout = (ViewGroup) findViewById(android.R.id.content).getRootView(); 

progressBar = new ProgressBar(thisActivity,null,android.R.attr.progressBarStyleLarge); 
progressBar.setIndeterminate(true); 
progressBar.setVisibility(View.VISIBLE); 

RelativeLayout.LayoutParams params = new 
     RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.MATCH_PARENT); 

RelativeLayout rl = new RelativeLayout(thisActivity); 

rl.setGravity(Gravity.CENTER); 
rl.addView(progressBar); 

layout.addView(rl,params); 

Answer 3

您不需要XML。您可以通過代碼的所有創建視圖：

@Override 
protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     LinearLayout layout = new LinearLayout(this); 
     ProgressBar pb = new ProgressBar(this, null, 
             android.R.attr.progressBarStyleLarge); 
     ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
       ViewGroup.LayoutParams.WRAP_CONTENT, 
       ViewGroup.LayoutParams.WRAP_CONTENT); 
     pb.setLayoutParams(params); 
     layout.setGravity(Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL); 
     layout.addView(pb); 
     setContentView(layout); 
} 

Answer 4

我寫了基於@類DharmarajRupakheti的answer：

public class ProgressBarHandler { 
    private ProgressBar mProgressBar; 
    private Context mContext; 

    public ProgressBarHandler(Context context) { 
     mContext = context; 

     ViewGroup layout = (ViewGroup) ((Activity) context).findViewById(android.R.id.content).getRootView(); 

     mProgressBar = new ProgressBar(context, null, android.R.attr.progressBarStyleLarge); 
     mProgressBar.setIndeterminate(true); 

     RelativeLayout.LayoutParams params = new 
       RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT); 

     RelativeLayout rl = new RelativeLayout(context); 

     rl.setGravity(Gravity.CENTER); 
     rl.addView(mProgressBar); 

     layout.addView(rl, params); 

     hide(); 
    } 

    public void show() { 
     mProgressBar.setVisibility(View.VISIBLE); 
    } 

    public void hide() { 
     mProgressBar.setVisibility(View.INVISIBLE); 
    } 
} 

用法：

mProgressBarHandler = new ProgressBarHandler(this); // In onCreate 
mProgressBarHandler.show(); // To show the progress bar 
mProgressBarHandler.hide(); // To hide the progress bar