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  • 监听内容变化 TextWatcher @功能

    监听多个TextView的内容变化

    使用示例
    TextWatcherUtils.addTextChangedListener(isAllNotEmpty -> btnLogin.setEnabled(isAllNotEmpty), etCode, etPhone);
    /**
 * Desc：用于监听多个TextView的内容变化，常用于判断在登录注册时同时判断多个EditText是否都有输入内容，以判断是否允许点击下一步
 *
 * @author 白乾涛 <p>
 * @tag 内容变化<p>
 * @date 2018/5/22 22:01 <p>
 */
public class TextWatcherUtils {
	
	public interface OnTextChangedListener {
		void onTextChanged(boolean isAllNotEmpty);
	}
	
	public static void addTextChangedListener(OnTextChangedListener listener, TextView... tvs) {
		for (TextView textView : tvs) {
			textView.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) {
					if (listener != null) {
						listener.onTextChanged(isAllTextViewNotEmpty(tvs));
					}
				}
			});
		}
	}
	
	private static boolean isAllTextViewNotEmpty(TextView[] tvs) {
		for (TextView tv : tvs) {
			if (TextUtils.isEmpty(tv.getText())) {
				return false;
			}
		}
		return true;
	}
}

    仿QQ、微信、钉钉的@功能 案例

    功能
    1、如果增加或减少或替换后改变的文本以@结尾，则弹出选择成员界面
    2、如果在【某个昵称之间】增加或减少或替换了一些字符，则在@列表中去除此昵称
    3、如果是在紧挨着某个昵称之后减少了一些字符，则删除掉文本框中的此昵称，并在@列表中去除此昵称
    public class MainActivity extends Activity {
   private ArrayList<String> selectedIds = new ArrayList<>();
   private ArrayList<SimpleBean> indexs = new ArrayList<SimpleBean>();
   private EditText et;

   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      et = new EditText(this);
      setContentView(et);

      et.addTextChangedListener(new TextWatcher() {
         @Override
         public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            //This method is called to notify you that,
            // within [s], the [count] characters beginning at [start] are about to be replaced by new text with length [after].
            // It is an error to attempt to make changes to s from this callback.
            //Log.i("bqt", "【beforeTextChanged】" + s + "   " + start + "   " + after + "   " + count);
         }

         @Override
         public void onTextChanged(CharSequence s, int start, int before, int count) {
            //This method is called to notify you that,
            //within [s], the [count] characters beginning at [start] have just replaced old text that had length [before].
            //It is an error to attempt to make changes to [s] from this callback.
            //在s中，从start位置开始，有before个字符被count个字符【替换】了
            //s 表示改变后输入框中的字符串，start 表示内容是从哪个位置(从0开始)开始改变的
            //如果before!=0，代表字符被替换了(可能增加了也可能减少了)；如果before=0，可以确定是增加了count个字符

            //*************************************************测试代码*****************************************
            Log.i("bqt", "【onTextChanged】" + s + "   " + start + "   " + before + "   " + count);
            if (before == 0) Log.i("bqt", "【直接增加了一些字符】" + start + " " + count + " " + before);
            else {//替换或减少了一些字符
               if (count - before > 0) Log.i("bqt", "【替换后增加了一些字符】" + start + " " + count + " " + before);
               else if (count - before == 0) Log.i("bqt", "【替换后字符个数没有变】" + start + " " + count + " " + before);
               else {
                  if (count == 0) Log.i("bqt", "【直接减少了一些字符】" + start + " " + count + " " + before);
                  else Log.i("bqt", "【替换后减少了一些字符】" + start + " " + count + " " + before);
               }
            }

            //***********************************************@逻辑代码*******************************************
            if (before != 0 && count - before < 0) {//如果是减少了一些字符
               for (final SimpleBean sbean : indexs) {
                  if (start == sbean.end || start == sbean.end - 1) {//如果是在某个昵称之后减少了一些字符
                     if (selectedIds != null) selectedIds.remove(sbean.userAlias);//如果是的话，在@列表中去除此昵称
                     Log.i("bqt", "【删除掉文本框中的此昵称】");
                     et.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                           et.getEditableText().replace(sbean.start, sbean.end, "");//删除掉文本框中的此昵称
                        }
                     }, 100);
                  }
               }
            }

            for (SimpleBean sbean : indexs) {
               if (start > sbean.start && start < sbean.end) {//是否在【某个昵称之间】增加或减少或替换了一些字符
                  Log.i("bqt", "【在某个昵称之间_替换_了一些字符】" + sbean.start + " " + start + " " + sbean.end);
                  if (selectedIds != null) selectedIds.remove(sbean.userAlias);//如果是的话，在@列表中去除此昵称
               }
            }

            if (start + count - 1 >= 0 && s.toString().charAt(start + count - 1) == '@') {//如果增加或减少或替换后改变的文本以@结尾
               showSingleChoiceDialog();
            }
         }

         @Override
         public void afterTextChanged(Editable s) {
            //Log.i("bqt", "【afterTextChanged】" + s.toString());
            indexs.clear();//先清空
            //当输入内容后把所有信息封装起来
            if (selectedIds != null && selectedIds.size() > 0) {
               for (String userAlias : selectedIds) {
                  String newUserAlias = "@" + userAlias;
                  int startIndex = et.getText().toString().indexOf(newUserAlias);//注意。这里把@加进去了
                  int endIndex = startIndex + newUserAlias.length();
                  indexs.add(new SimpleBean(userAlias, startIndex, endIndex));
                  Log.i("bqt", userAlias + "的【边界值】" + startIndex + "  " + endIndex);
               }
               Log.i("bqt", "【选择的id有：】" + Arrays.toString(selectedIds.toArray(new String[selectedIds.size()])));
            }
         }
      });
   }

   //单选对话框
   public void showSingleChoiceDialog() {
      final String[] items = {"白乾涛", "包青天", "baiqiantao"};
      AlertDialog dialog = new AlertDialog.Builder(this)//
            .setTitle("请选择")//
            .setPositiveButton("确定", null).setNegativeButton("取消", null)
            .setSingleChoiceItems(items, -1, new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int which) {
                  if (selectedIds == null) selectedIds = new ArrayList<>();
                  selectedIds.add(items[which]);//先把选择的内容存起来再更改EditText中的内容

                  //先把选择的内容存起来再更改EditText中的内容，顺序不能反
                  int index = et.getSelectionStart();//获取光标所在位置
                  et.getEditableText().insert(index, items[which] + " ");//在光标所在位置插入文字
                  dialog.dismiss();
               }
            })
            .create();
      dialog.show();
   }

   static class SimpleBean {
      public int start;
      public int end;
      public String userAlias;

      public SimpleBean(String userAlias, int start, int end) {
         this.userAlias = userAlias;
         this.start = start;
         this.end = end;
      }
   }
}

    2018-5-22
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  • 原文地址：https://www.cnblogs.com/baiqiantao/p/6802979.html
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