android的文本更改监听器

我有一个情况，有两个领域。Field1和field2。我想要的当field1被改变时，要做的是空field2，反之亦然。所以只有在最后一个字段上有内容。

field1 = (EditText)findViewById(R.id.field1);
field2 = (EditText)findViewById(R.id.field2);

field1.addTextChangedListener(new TextWatcher() {

   public void afterTextChanged(Editable s) {}

   public void beforeTextChanged(CharSequence s, int start,
     int count, int after) {
   }

   public void onTextChanged(CharSequence s, int start,
     int before, int count) {
      field2.setText("");
   }
  });

field2.addTextChangedListener(new TextWatcher() {

   public void afterTextChanged(Editable s) {}

   public void beforeTextChanged(CharSequence s, int start,
     int count, int after) {
   }

   public void onTextChanged(CharSequence s, int start,
     int before, int count) {
     field1.setText("");
   }
  });

它工作得很好，如果我附加addTextChangedListener到field1，但当我对两个字段都这么做，应用程序崩溃了。显然是因为他们想要改变无限地相互联系。一旦field1改变，此时它就会清除field2 Field2被更改，因此它将清除field1，以此类推……

谁能给点建议吗?

当前回答

另一个可能会帮助别人的解决方案。有2个EditText，它们在编辑后相互改变。默认情况下，它导致了周期性。

使用变量:

Boolean uahEdited = false;
Boolean usdEdited = false;

添加TextWatcher

uahEdit = findViewById(R.id.uahEdit);
usdEdit = findViewById(R.id.usdEdit);

uahEdit.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            if (!usdEdited) {
                uahEdited = true;
            }
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            String tmp = uahEdit.getText().toString();

            if(!tmp.isEmpty() && uahEdited) {
                uah = Double.valueOf(tmp);
                usd = uah / 27;
                usdEdit.setText(String.valueOf(usd));
            } else if (tmp.isEmpty()) {
                usdEdit.getText().clear();
            }
        }

        @Override
        public void afterTextChanged(Editable s) {
            uahEdited = false;
        }
    });

usdEdit.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            if (!uahEdited) {
                usdEdited = true;
            }
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            String tmp = usdEdit.getText().toString();

            if (!tmp.isEmpty() && usdEdited) {
                usd = Double.valueOf(tmp);
                uah = usd * 27;
                uahEdit.setText(String.valueOf(uah));
            } else if (tmp.isEmpty()) {
                uahEdit.getText().clear();
            }
        }

        @Override
        public void afterTextChanged(Editable s) {
            usdEdited = false;
        }
    });

不要批评太多。我是一个开发新手

2020-06-26 19:00:45

其他回答

这个回答有点晚了，但这里有一个可重复使用的解决方案:

/**
 * An extension of TextWatcher which stops further callbacks being called as 
 * a result of a change happening within the callbacks themselves.
 */
public abstract class EditableTextWatcher implements TextWatcher {

    private boolean editing;

    @Override
    public final void beforeTextChanged(CharSequence s, int start, 
                                                    int count, int after) {
        if (editing)
            return;

        editing = true;
        try {
            beforeTextChange(s, start, count, after);
        } finally {
            editing = false;
        }
    }

    protected abstract void beforeTextChange(CharSequence s, int start, 
                                                     int count, int after);

    @Override
    public final void onTextChanged(CharSequence s, int start, 
                                                int before, int count) {
        if (editing)
            return;

        editing = true;
        try {
            onTextChange(s, start, before, count);
        } finally {
            editing = false;
        }
    }

    protected abstract void onTextChange(CharSequence s, int start, 
                                            int before, int count);

    @Override
    public final void afterTextChanged(Editable s) {
        if (editing)
            return;

        editing = true;
        try {
            afterTextChange(s);
        } finally {
            editing = false;
        }
    }

    public boolean isEditing() {
        return editing;
    }

    protected abstract void afterTextChange(Editable s);
}

因此，当使用上述方法时，在TextWatcher中发生的任何setText()调用都不会导致TextWatcher再次被调用:

/**
 * A setText() call in any of the callbacks below will not result in TextWatcher being 
 * called again.
 */
public class MyTextWatcher extends EditableTextWatcher {

    @Override
    protected void beforeTextChange(CharSequence s, int start, int count, int after) {
    }

    @Override
    protected void onTextChange(CharSequence s, int start, int before, int count) {
    }

    @Override
    protected void afterTextChange(Editable s) {
    }
}

2017-04-15 10:24:14

我写了自己的扩展，对我很有帮助。(芬兰湾的科特林)

你可以这样写:

editText.customAfterTextChanged { editable -> 
    //You have accessed the editable object. 
}

我的分机号:

fun EditText.customAfterTextChanged(action: (Editable?)-> Unit){
    this.addTextChangedListener(object : TextWatcher {
       override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
       override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
       override fun afterTextChanged(editable: Editable?) {
        action(editable)
    }
})}

2019-09-25 12:42:07

etSearch.addTextChangedListener(object : TextWatcher {
     override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
          TODO("Not yet implemented")
     }

     override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
          TODO("Not yet implemented")
     }

     override fun afterTextChanged(p0: Editable?) {
          TODO("Not yet implemented")
     }
})

2022-09-23 17:15:54

您可以添加一个检查，只在字段中的文本不为空时清除(即当长度不等于0时)。

field1.addTextChangedListener(new TextWatcher() {

   @Override
   public void afterTextChanged(Editable s) {}

   @Override    
   public void beforeTextChanged(CharSequence s, int start,
     int count, int after) {
   }

   @Override    
   public void onTextChanged(CharSequence s, int start,
     int before, int count) {
      if(s.length() != 0)
        field2.setText("");
   }
  });

field2.addTextChangedListener(new TextWatcher() {

   @Override
   public void afterTextChanged(Editable s) {}

   @Override
   public void beforeTextChanged(CharSequence s, int start,
     int count, int after) {
   }

   @Override
   public void onTextChanged(CharSequence s, int start,
     int before, int count) {
      if(s.length() != 0)
         field1.setText("");
   }
  });

这里是TextWatcher的文档。

另外，请尊重命名约定。

2013-12-29 11:28:11