以编程方式将 ProgressBar 放在屏幕的中心答案

【问题标题】：Put ProgressBar in CENTER of the screen programmatically以编程方式将 ProgressBar 放在屏幕的中心
【发布时间】：2014-01-27 10:18:40
【问题描述】：

我正在创建一个扩展 LinearLayout 的课程。我正在尝试以编程方式进行布局。这是我到目前为止所做的：

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

    this.setLayoutParams(parentParam);
    this.setOrientation(LinearLayout.VERTICAL);

    WebView webView = new WebView(context);
    LinearLayout.LayoutParams webViewParam = new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.MATCH_PARENT,
            LinearLayout.LayoutParams.MATCH_PARENT);

    webView.setLayoutParams(webViewParam);
    this.addView(webView);

    pb = new ProgressBar(context);
    LinearLayout.LayoutParams pbParam = new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.WRAP_CONTENT,
            LinearLayout.LayoutParams.WRAP_CONTENT);
    pbParam.gravity = Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL;
    pb.setLayoutParams(pbParam);
    webView.addView(pb);

我的一切工作正常，WebView 和 ProgressBar 可见并在那里执行相应的任务，但我试图将 ProgressBar 放在屏幕的 CENTER 中。

我在这里错过了什么。任何形式的意见都将受到赞赏。

编辑： 现在的输出如下所示：

【问题讨论】：

你在输出中得到什么，在这里发布。
为什么要在webview中添加pb？您应该将 pb 添加到 this.addView
@PratikButani 添加图片
@blackbelt 因为我要在webview中加载一些内容，所以我需要在那里显示进度条。
我认为是RelativeLayout的问题。您必须以编程方式设置 android:layout_centerHorizontal="true" 和 android:layout_centerVertical="true"。

标签： android android-layout progress-bar

【解决方案1】：

这是我为将ProgressBar 带到中心所做的操作。我已将ScrollView 用于我的目的。这是我使用的代码：

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

    this.setLayoutParams(parentParam);
    this.setOrientation(LinearLayout.VERTICAL);

    scrollView = new ScrollView(context);
    scrollView.setLayoutParams(new FrameLayout.LayoutParams(
            FrameLayout.LayoutParams.MATCH_PARENT,
            FrameLayout.LayoutParams.MATCH_PARENT,
            Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL));
    scrollView.setFillViewport(true);

    scrollView.setBackgroundColor(Color.TRANSPARENT);

    pb = new ProgressBar(context);
    LinearLayout.LayoutParams pbParam = new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.WRAP_CONTENT,
            LinearLayout.LayoutParams.WRAP_CONTENT);
    pb.setLayoutParams(pbParam);

    RelativeLayout rel = new RelativeLayout(context);
    RelativeLayout.LayoutParams relParam = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);
    relParam.addRule(RelativeLayout.CENTER_IN_PARENT);
    rel.addView(pb, relParam);

    scrollView.addView(rel);

    webView = new WebView(context);
    LinearLayout.LayoutParams webViewParam = new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.MATCH_PARENT,
            LinearLayout.LayoutParams.MATCH_PARENT);
    webViewParam.gravity = Gravity.CENTER_HORIZONTAL
            | Gravity.CENTER_VERTICAL;
    webView.setLayoutParams(webViewParam);

    this.addView(scrollView);

    this.addView(webView);

希望，这会帮助其他正在尝试同样事情的人。

【讨论】：

【解决方案2】：

// try this way
1. Custom Linear Layout
public class MyCustomLinearLayout extends LinearLayout {
    private FrameLayout frameLayout;
    private ProgressBar pb;
    private  WebView webView;
    public MyCustomLinearLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    public MyCustomLinearLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public MyCustomLinearLayout(Context context) {
        super(context);
        init(context);
    }

    private void init(Context mContext) {
        frameLayout = new FrameLayout(mContext);
        frameLayout.setLayoutParams(new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT));
        webView = new WebView(mContext);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setPluginState(WebSettings.PluginState.ON);
        webView.getSettings().setSupportZoom(true);
        webView.getSettings().setBuiltInZoomControls(true);
        webView.setWebChromeClient(new WebChromeClient() {
            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                super.onProgressChanged(view, newProgress);
                if (newProgress >= 1) {
                    pb.setVisibility(View.VISIBLE);
                }
                if (newProgress == 100) {
                    pb.setVisibility(View.GONE);
                }
            }
        });
        webView.setWebViewClient(new WebViewClient());
        webView.loadUrl("http://www.google.com");
        frameLayout.addView(webView);
        pb = new ProgressBar(mContext);
        FrameLayout.LayoutParams parms = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT);
        parms.gravity = Gravity.CENTER;
        frameLayout.addView(pb,parms);
        addView(frameLayout);
    }


}

【讨论】：

【解决方案3】：

    LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(150, 150);
    lp.weight = 1.0f;
    lp.gravity = Gravity.CENTER;

    ProgressBar pDialog = new ProgressBar(currentActivity);
    pDialog.setIndeterminateDrawable(currentActivity.getResources().getDrawable(R.drawable.progressload));

    LinearLayout ll = new LinearLayout(currentActivity);
    ll.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
    ll.setOrientation(LinearLayout.VERTICAL);
    ll.addView(pDialog, lp);

【讨论】：