版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/mChenys/article/details/85707203
扫描Activity
public static Activity scanForActivity(Context ctx) {
if (ctx == null)
return null;
else if (ctx instanceof Activity)
return (Activity) ctx;
else if (ctx instanceof ContextWrapper)
return scanForActivity(((ContextWrapper) ctx).getBaseContext());
return null;
}
一般用于在Dialog中show的时候判断Activity的引用是否有效,例如:
@Override
public void show() {
Activity activity = UIUtils.scanForActivity(getContext());
if (null != activity && !activity.isFinishing())
super.show();
}
给drawableRight设置点击事件
例如EditText右侧有一个删除按钮是通过drawableRight属性设置的,此时如果想让其响应点击事件,这可以通过判断点击的坐标位置与删除按钮的位置对比,下面是通过处理点击删除按钮删除EditText框的内容
/**
* 给EditText的右侧drawableRight属性的图片设置点击事件
*
* @param editText
*/
public static void registerEditRightDrawableClickListener(final EditText editText) {
editText.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
// et.getCompoundDrawables()得到一个长度为4的数组，分别表示左上右下四张图片
Drawable drawable = editText.getCompoundDrawables()[2];
//如果右边没有图片，不再处理
if (drawable == null)
return false;
//如果不是按下事件，不再处理
if (event.getAction() != MotionEvent.ACTION_UP)
return false;
if (event.getX() > editText.getWidth() - editText.getPaddingRight() - drawable.getIntrinsicWidth()) {
editText.setText("");
return true;
}
return false;
}
});
}
限制EditText可输入的字数,超出后提示文案
/**
* 限制EditText可输入的字数,超出后提示文案
*
* @param editText 目标view
* @param maxLength 最大字数
* @param msg 提示文案
* @param callback 回调接口
*/
public static void registerEditMaxTextShow(final EditText editText, final int maxLength, final String msg, final Callback callback) {
editText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
String currMsg = editText.getText().toString().trim();
if (null != callback) callback.onEditTextChange(currMsg);
if (currMsg.length() > maxLength) {
ToastUtils.showShort(msg);
int editStart = editText.getSelectionStart();
int editEnd = editText.getSelectionEnd();
s.delete(editStart - 1, editEnd);
String finalMsg = s.toString();
editText.removeTextChangedListener(this);
editText.setText(finalMsg);
editText.setSelection(finalMsg.length());
if (null != callback) callback.onEditTextChange(finalMsg);
editText.addTextChangedListener(this);
}
}
});
}
//回调接口
public interface Callback {
void onEditTextChange(String msg);
}
解决RecycleView布局中GridLayoutManager和StaggeredGridLayoutManager添加头部和底部不占用一行的问题
重写RecyclerView.Adapter的2个方法
/**
* 解决GridLayoutManager添加头部和底部不占用一行的问题
*
* @param recyclerView
*/
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
if (manager instanceof GridLayoutManager) {
final GridLayoutManager gridManager = ((GridLayoutManager) manager);
gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
return (isHeaderViewPosition(position) || isFooterViewPosition(position))
? gridManager.getSpanCount() : 1;
}
});
}
mAdapter.onAttachedToRecyclerView(recyclerView);
}
/**
* 解决StaggeredGridLayoutManager添加头部和底部不占用一行的问题
*
* @param holder
*/
@Override
public void onViewAttachedToWindow(RecyclerView.ViewHolder holder) {
super.onViewAttachedToWindow(holder);
ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
int position = holder.getLayoutPosition();
if (lp != null
&& lp instanceof StaggeredGridLayoutManager.LayoutParams
&& (isHeaderViewPosition(position) || isFooterViewPosition(position))) {
StaggeredGridLayoutManager.LayoutParams p = (StaggeredGridLayoutManager.LayoutParams) lp;
p.setFullSpan(true);
}
mAdapter.onViewAttachedToWindow(holder);
}
重写RecycleView的setLayoutManager方法
/**
* 解决GridLayoutManager添加头部和底部不占用一行的问题
*
* @param layout
*/
@Override
public void setLayoutManager(LayoutManager layout) {
super.setLayoutManager(layout);
if (mWrapAdapter != null) {
if (layout instanceof GridLayoutManager) {
final GridLayoutManager gridManager = ((GridLayoutManager) layout);
gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int position) {
return (mWrapAdapter.isHeaderViewPosition(position) || mWrapAdapter.isFooterViewPosition(position))
? gridManager.getSpanCount() : 1;
}
});
}
}
}
解决由于RecyclerView有刷新头存在，导致canScrollVertically(-1)时始终返回true的bug
@Override
public boolean canScrollVertically(int direction) {
if (direction < 1) {
boolean original = super.canScrollVertically(direction);
if (!original || getChildAt(0) != null && getChildAt(0).getTop() >= 0) {
return false;
} else {
return true;
}
}
return super.canScrollVertically(direction);
}
获取RecycleView第一个和最后一个可见Item的位置
/**
* 获取第一个可见的item位置
* @return
*/
public int getFirstVisiablePosition() {
LayoutManager layoutManager = getLayoutManager();
int firstVisibleItemPosition;
if (layoutManager instanceof GridLayoutManager) {
firstVisibleItemPosition = ((GridLayoutManager) layoutManager).findFirstVisibleItemPosition();
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
int[] into = new int[((StaggeredGridLayoutManager) layoutManager).getSpanCount()];
((StaggeredGridLayoutManager) layoutManager).findFirstVisibleItemPositions(into);
firstVisibleItemPosition = findMin(into);
} else {
firstVisibleItemPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
}
return firstVisibleItemPosition;
}
/**
* 获取可见列表内最后一个item的位置
*
* @return
*/
public int getLastVisibleItemPosition() {
int lastVisibleItemPosition;
LayoutManager layoutManager = getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
lastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition();
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
int[] into = new int[((StaggeredGridLayoutManager) layoutManager).getSpanCount()];
((StaggeredGridLayoutManager) layoutManager).findLastVisibleItemPositions(into);
lastVisibleItemPosition = findMax(into);
} else {
lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
}
return lastVisibleItemPosition;
}
private int findMin(int[] firstPositions) {
int min = firstPositions[0];
for (int value : firstPositions) {
if (value < min) {
min = value;
}
}
return min;
}
private int findMax(int[] lastPositions) {
int max = lastPositions[0];
for (int value : lastPositions) {
if (value > max) {
max = value;
}
}
return max;
}
修改RadioButton的drawableRight图片与文字相隔的距离太大,导致drawablePadding设置无效
重写AppCompatRadioButton的onDraw方法
@Override
protected void onDraw(Canvas canvas) {
//得到Drawable集合 分别对应 左上右下
Drawable[] drawables = getCompoundDrawables();
if (drawables != null) {
//获取右边图片,修改drawableRight的图片紧贴着文字
Drawable drawableRight = drawables[2];
if (drawableRight != null) {
//获取文字占用长宽
int textWidth = (int) getPaint().measureText(getText().toString());
int textHeight = (int) getPaint().getTextSize();
//获取图片实际长宽
int drawableWidth = drawableRight.getIntrinsicWidth();
int drawableHeight = drawableRight.getIntrinsicHeight();
//setBounds修改Drawable在View所占的位置和大小,对应参数同样的 左上右下()
int bodyWidth = textWidth + drawableWidth + getCompoundDrawablePadding();
int left = (bodyWidth - getWidth()) / 2;
int right = left + drawableWidth;
drawableRight.setBounds(left, 0, right, drawableHeight);
}
}
super.onDraw(canvas);
}
解决RadioButton无法重复点击取消选中的状态
重写AppCompatRadioButton的toggle方法
@Override
public void toggle() {
setChecked(!isChecked());
if (!isChecked()) {
if (null != getParent() && getParent() instanceof RadioGroup)
((RadioGroup) getParent()).clearCheck();
}
}
解决手动设置Switch的setChecked方法导致setOnCheckedChangeListener触发响应
mPushSwt.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (buttonView.isPressed()) { //避免代码设置setChecked状态导致回调监听
//do sth...
}
}
});
避免SwipeRefreshLayout重复下拉导致刷新按钮异常显示
重写SwipeRefreshLayout的onStartNestedScroll方法
@Override
public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
//避免重复下拉刷新导致动画异常
return !isRefreshing() && super.onStartNestedScroll(child, target, nestedScrollAxes);
}
更新于2019-01-03
TextView的drawableLeft与文本无法一起居中显示
TextView设置的文本默认是存在一个上下间距的，也就是上下空白，当我们在使用drawableLeft的时候，这个默认的空白会使TextView中的文本向下偏移，当你的drawableLeft使用的icon很小，文字的size也很小的时候，即使你设置了android:gravity=“center”，也能很明显的看到你的TextView中的文本基本上是与icon处于底边对其，而不是居中对其
只要TextView中加上android:includeFontPadding=“false” 这个属性属性就可以了!