自定义弹出框中，Edittext监听当前输入的字数，并且提示是否为空

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这是一个自定义弹出框

 	public void showReNameWindow(TextView tv_location,int Location){
        View contentview = LayoutInflater.from(context).inflate(R.layout.rewrite_name_popwin, null);
        edt=contentview.findViewById(R.id.pop_rewrite_edt);
        TextView tv_size=contentview.findViewById(R.id.pop_rewrite_tv_size);
        TextWatcher mTextWatcher = new TextWatcher() {
            private CharSequence temp;
            private int editStart ;
            private int editEnd ;
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                // TODO Auto-generated method stub
                temp = s;
            }

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count,
                                          int after) {
                // TODO Auto-generated method stub
                //          mTextView.setText(s);//将输入的内容实时显示
            }

            @Override
            public void afterTextChanged(Editable s) {
                // TODO Auto-generated method stub
                editStart = edt.getSelectionStart();
                editEnd = edt.getSelectionEnd();
                tv_size.setTextColor(R.color.text_grey);
                tv_size.setText(temp.length() + "/100");
                if (temp.length() > 100) {
                    s.delete(editStart-1, editEnd);
                    int tempSelection = editStart;
                    tv_size.setTextColor(Color.RED);
                    tv_size.setText(temp.length() + "/100");
                    edt.setSelection(tempSelection);
                }
            }
        };
        edt.addTextChangedListener(mTextWatcher);
        TextView tv=contentview.findViewById(R.id.pop_rewrite_tv);
        TextView tv_enter=contentview.findViewById(R.id.pop_enterhistory_tv);
        tv_enter.setVisibility(View.GONE);
        edt.setText(tv_location.getText());
        PopupWindow pw = new PopupWindow(contentview, WindowManager.LayoutParams.MATCH_PARENT, WindowManager.LayoutParams.WRAP_CONTENT, true);
        tv.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (TextUtils.isEmpty(edt.getText())){
                    Toast.makeText(context,"名称不能为空",Toast.LENGTH_SHORT).show();
                }else {
                    RewriteData(qipanJiluAcitivity.getId(Location), edt.getText().toString());
                    tv_location.setText(edt.getText());//将按钮设置为当前，是不是需要重新获取列表。
                    list.set(Location, tv_location.getText().toString());
                    listData.set(Location, tv_location.getText().toString());
                    pw.dismiss();
                }
            }
        });
//当保存数据操作时，则其他变量应该修改为成员变量，要不然，第一遍弹出框没错，第二次框弹出就会出错
        pw.showAsDropDown(tv_location);
    }