目前實現一個Toolbar標題欄居中一般是Toolbar佈局檔案裡面新增一個TextView

然而某些情況下我們不想在Toolbar佈局檔案裡面新增一個佈局，於是可以這麼封裝

    private void setTitleCenter(Toolbar toolbar) {
        TextView titleText = new TextView(getActivity());
        titleText.setTextColor(ContextCompat.getColor(getActivity(), R.color.colorWhite));
        titleText.setText
 
(R.string.fragment_task_title_text);
        titleText.setTextSize(18);
        titleText.setGravity(Gravity.CENTER);
        Toolbar.LayoutParams layoutParams = new Toolbar.LayoutParams(Toolbar.LayoutParams.WRAP_CONTENT, Toolbar.LayoutParams.WRAP_CONTENT);
        layoutParams.gravity = Gravity.CENTER
 
;
        titleText.setLayoutParams(layoutParams);
        toolbar.addView(titleText);
    }

Toolbar系統自帶的標題居中：

如果不想自己寫個TextView，想使用Toolbar系統自帶的標題居中，同樣也只需要一行程式碼呼叫

    public void setTitleCenter(Toolbar toolbar) {
        String title = "title";
        final CharSequence originalTitle = toolbar.getTitle
 
();
        toolbar.setTitle(title);
        for (int i = 0; i < toolbar.getChildCount(); i++) {
            View view = toolbar.getChildAt(i);
            if (view instanceof TextView) {
                TextView textView = (TextView) view;
                if (title.equals(textView.getText())) {
                    textView.setGravity(Gravity.CENTER);
                    Toolbar.LayoutParams params = new Toolbar.LayoutParams(Toolbar.LayoutParams.WRAP_CONTENT, Toolbar.LayoutParams.MATCH_PARENT);
                    params.gravity = Gravity.CENTER;
                    textView.setLayoutParams(params);
                }
            }
            toolbar.setTitle(originalTitle);
        }
    }

兩種方式任各位大佬選擇，只需要呼叫一行程式碼

setTitleCenter(toolbar);

OK了