Android：无法将以编程方式添加的编辑文本对齐到屏幕顶部

Question

嘿，我正在向我的片段添加自定义编辑文本，但出于某种原因我无法将其与屏幕顶部对齐。它总是在屏幕中间结束。

"NotePad" 编辑文字：

public class LinedEditText extends EditText {
    private Rect mRect;
    private Paint mPaint;

    // we need this constructor for LayoutInflater
    public LinedEditText(Context context) {
        super(context);

        mRect = new Rect();
        mPaint = new Paint();
        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
        mPaint.setColor(getResources().getColor(R.color.textColorPrimary)); //SET YOUR OWN COLOR HERE
    }

    @Override
    protected void onDraw(Canvas canvas) {
        //int count = getLineCount();

        int height = getHeight();
        int line_height = getLineHeight();

        int count = height / line_height;

        if (getLineCount() > count)
            count = getLineCount();//for long text with scrolling

        Rect r = mRect;
        Paint paint = mPaint;
        int baseline = getLineBounds(0, r);//first line

        for (int i = 0; i < count; i++) {

            canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);
            baseline += getLineHeight();//next line
        }

        super.onDraw(canvas);
    }
}

设置布局参数并添加到布局的代码：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View rootView = inflater.inflate(R.layout.fragment_note, container, false);
    LinedEditText linedEditText = new LinedEditText(getActivity());
    RelativeLayout relativeLayout = (RelativeLayout) rootView.findViewById(R.id.note_relative_layout);

    RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
    params.alignWithParent = true;
    params.addRule(RelativeLayout.ALIGN_TOP);
    linedEditText.setLayoutParams(params);
    relativeLayout.addView(linedEditText);
    return rootView;}

XML:

<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="com.glenn.sacramenttalktool.NoteFragment"
android:id="@+id/note_relative_layout"
android:gravity="top">

我试过使用 FrameLayout、LinearLayout 和 RelativeLayout，但行为是一样的。我只需要让编辑文本与屏幕顶部对齐。

主要activity布局

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:layout_scrollFlags="scroll|enterAlways"
        app:popupTheme="@style/ThemeOverlay.ldsTalkTool">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="LDS Talk Tool"
        android:textSize="20sp"
        android:textStyle="bold"
        android:textColor="@color/textColorPrimary"
        android:id="@+id/toolbar_title" />
    </android.support.v7.widget.Toolbar>

    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabMode="fixed"
        app:tabGravity="fill"/>
</android.support.design.widget.AppBarLayout>

<android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"  />

我试过像这样将它添加到 XML，尽管这会引发错误：

<com.glenn.[app_name].LinedEditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

Answer 1

试试这个。变化：

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

至：

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

Answer 2

原来我已经从 LinedEditText 的构造函数中删除了 AttributeSet 参数 class。

public LinedEditText(Context context) {
    super(context);

根据这个 Error inflating when extending a class 上下文和 AttributeSet 都需要膨胀视图，这就是为什么当我试图在 XML 中添加视图时它抛出错误的原因。它应该是这样的：

public LinedEditText(Context context, AttributeSet attrs) {
    super(context, attrs);

修复后我可以直接将它添加到 XML 并将重力设置为 "start"。它现在填满了屏幕。

Android：无法将以编程方式添加的编辑文本对齐到屏幕顶部

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