java - 如何在创建 View 时测量 View 的宽度？

Question

我正在尝试连接单个单词的 TextViews 并创建它们的多行。为了确定何时创建新行，我需要检查单词的 TextView 的宽度。

这是一张类似于我想要完成的图片

当我尝试使用 getWidth 时出现奇怪的错误:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.widget.RelativeLayout.getWidth()' on a null object reference

但是，当我调试代码时，rL2 不为空并且有一个值。

我猜我的 View 还没有创建？但是我怎样才能动态地改变它呢？我怎样才能做我的行？

这是我的代码:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View v = inflater.inflate(R.layout.fragment_call_response, container, false);
    v.measure(widthMeasureSpec, heightMeasureSpec);
    int lineWidth = 0;

    RelativeLayout rL2 = (RelativeLayout) v.findViewById(R.id.row1);
    int lineCount = 0;
    int rowWidth = rL2.getWidth();

    int wordCountRow = 0;


    TextView question = (TextView) v.findViewById(R.id.Question);
    TextView choice1 = (TextView) v.findViewById(R.id.choice1);
    TextView choice2 = (TextView) v.findViewById(R.id.choice2);
    TextView choice3 = (TextView) v.findViewById(R.id.choice3);
    TextView choice4 = (TextView) v.findViewById(R.id.choice4);
    TextView speaker = (TextView) v.findViewById(R.id.Speaker);
    TextView progress = (TextView) v.findViewById(R.id.progress);


    ArrayList<String> answers = new ArrayList<>();
    answers.addAll(quote.getAnswerChoice());
    answers.add(quote.getWordSplitTypeA().get(quote.getAnswerIndex().get(0)));
    Collections.shuffle(answers);

    speaker.setText("How would " + quote.getSpeaker().get(0) + " Marx answer the above question?");
    choice1.setText(answers.get(0));
    choice2.setText(answers.get(1));
    choice3.setText(answers.get(2));
    choice4.setText(answers.get(3));

    progress.setText(String.format("%.1f%% Complete", (SingletonFactory.getPlayer().getLessonProgress()[0] / 12.0) * 100));

    //addTextViews(v);


    for(int i = 0;i<quote.getWordSplitTypeA().size(); i++) {

        if (lineWidth + 10 > rowWidth) {
            lineCount++;
            wordCountRow = 0;
        }

        int padding = getResources().getDimensionPixelOffset(R.dimen.wordBoxPadding);
        TextView tv = new TextView(getActivity());
        tv.setId(i);
        tv.setText(quote.getWordSplitTypeA().get(i));
        tv.setBackgroundColor(Color.parseColor(bGColor));
        tv.setTextColor(Color.WHITE);
        tv.setGravity(Gravity.CENTER);
        tv.setPadding(padding, padding, padding, padding);
        ViewGroup.LayoutParams LP = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        tv.setLayoutParams(LP);

        RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) tv.getLayoutParams();

        if (wordCountRow == 0) {
            params.addRule(RelativeLayout.CENTER_VERTICAL);
            params.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
            params.addRule(RelativeLayout.ALIGN_PARENT_START);
        } else {
            params.addRule(RelativeLayout.CENTER_VERTICAL);
            params.addRule(RelativeLayout.RIGHT_OF, (i - 1));
        }

        tv.setLayoutParams(params);

        if (quote.getAnswerIndex().contains(i)) {
            tv.setBackgroundColor(Color.RED);
            tv.setText(".....");
        }
        int width = tv.getWidth();
        lineWidth += width;
        if (lineCount == 0) {
            RelativeLayout rL = (RelativeLayout) v.findViewById(R.id.row1);
            rL.addView(tv);
        } else if (lineCount == 1) {
            RelativeLayout rL = (RelativeLayout) v.findViewById(R.id.row2);
            rL.addView(tv);
        } else if (lineCount == 2) {
            RelativeLayout rL = (RelativeLayout) v.findViewById(R.id.row3);
            rL.addView(tv);
        } else if (lineCount == 3) {
            RelativeLayout rL = (RelativeLayout) v.findViewById(R.id.row4);
            rL.addView(tv);
        }


        choice1.setOnClickListener(mClickListener);
        choice2.setOnClickListener(mClickListener);
        choice3.setOnClickListener(mClickListener);
        choice4.setOnClickListener(mClickListener);

        question.setText(quote.getSpeaker().get(0) + ": " + quote.getQuote().get(0));
    }
    return v;
}

Answer 1

How can I measure the width of my views as I create them?

你不能。这是在测量和布局过程中处理的，这发生在您创建小部件之后。

I'm trying to connect TextViews of single words and create multilpe rows of them.

看起来你应该使用 a FlowLayout ，或类似的东西，作为 TextViews 的容器，它将自动包装它们。

如果 FlowLayout 不能满足您的需求，here is another one .

而且，如果这些都不是您想要的，您可以使用它们作为灵感来编写您自己的。您尝试实现的 UI 规则应该在容器中实现，因为容器会处理其子项的大小和定位。