有没有办法在您在 Android Studio 中键入时显示文本？

Question

当您在 Android Studio 的文本字段中键入输入时，是否有办法在屏幕上自动显示文本？

例如，如果我输入一个数字，它会自动乘以 20，结果会显示在文本字段下方的屏幕上。

Answer 1

一种简单的方法是使用 Textview 事件侦听器来处理您的操作！ 这是你可以做到的。

    field1 = (EditText)findViewById(R.id.field2);
    
    field1.addTextChangedListener(new TextWatcher() 
    {        
       public void afterTextChanged(Editable s)    
     {     //Called after the changes have been applied to the text.
           //You can change the text in the TextView from this method.

     }  
       public void beforeTextChanged(CharSequence s, int start,
         int count, int after) {
         //Called before the changes have been applied to the text.

       }
    
       public void onTextChanged(CharSequence s, int start,int before, int count) {
          TextView.setText("Here is the changing text"+s);
     //Similar to the beforeTextChanged method but called after the text changes.
    
    
       }
      });

/* 你可以防止这样的无限循环

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

            _ignore = true; // prevent infinite loop
            // Change your text here.
            // myTextView.setText(myNewText);
            _ignore = false; // release, so the TextWatcher start to listen again.
        }
*/

Answer 2

我无法正确理解这个问题，所以这里是两种不同情况的解决方案。

1. 要显示的文本在同一个 Activity 或 Fragment 中。 使用这样的 TextWatcher 类

et1.addTextChangedListener(new TextWatcher() {
    @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.
newTextView.text=s.toString; 
    }

    @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. 
    }

    @Override
    public void afterTextChanged(Editable s) {

    // This method is called to notify you that, somewhere within s, the text has been changed. 
    

    }
});

1. 输出在不同的屏幕（片段/抽屉）中

您可以结合使用 TextWatcher 和 LiveData。 在您的 editText 上放置一个 TextWatcher 并将数据存储在 Livedata 中。 (https://developer.android.com/topic/libraries/architecture/livedata) 然后观察这个 liveData 并相应地更改 Textview。