在Android中以编程方式对中ProgressBar

Question

我正在尝试ProgressBar使用以下内容以编程方式居中:

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);

大小设置似乎工作正常,但ProgressBar不在现有布局(由具有相对布局的xml定义)中.这里有什么明显的错误吗？

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>

即它只是一个空的相对布局来测试,看看我是否可以通过编程方式添加进度条.

谢谢.

Answer 1

我根据@ DharmarajRupakheti的答案写了一堂课:

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

Answer 2

如果你想以编程方式进行,你可以像下面这样做:

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 3

使用此样式的编码,可以得到您想要的结果.

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);