Question

我有三个Edittext。当我更改第一个Edittext值时，第三个Edittext值将由Textwatcher更改。当我更改第三个Edittext时，第一个edittext值将由Textwatcher更改。当我运行代码时，正在删除。

这是我的代码

   qty = (EditText) findViewById(R.id.qty);
   rate = (EditText) findViewById(R.id.rate);
   amount = (EditText) findViewById(R.id.amount);

   qty.addTextChangedListener(new TextWatcher() {
       @Override
       public void onTextChanged(CharSequence s, int start, int before, int count) { 
           // TODO Auto-generated method stub
       }

       @Override
       public void beforeTextChanged(CharSequence s, int start, int count, int after) {
           // TODO Auto-generated method stub
       }

       @Override
       public void afterTextChanged(Editable s) {
           // TODO Auto-generated method stub
           String qtyvalue = qty.getText().toString();
           String ratevalue = rate.getText().toString();

           if (qtyvalue.equals("") || ratevalue.equals("")) {
               val1 = 0d;
               val2 = 0d;
           } else {
               val1 = Double.parseDouble(qtyvalue);
               val2 = Double.parseDouble(ratevalue);
           }

           amount.setText(Double.toString(val1 * val2));
       }
   });

   amount.addTextChangedListener(new TextWatcher() {
       @Override
       public void onTextChanged(CharSequence s, int start, int before, int count) {
           // TODO Auto-generated method stub
       }

       @Override
       public void beforeTextChanged(CharSequence s, int start, int count, int after) {
           // TODO Auto-generated method stub
       }

       @Override
       public void afterTextChanged(Editable s) {
           // TODO Auto-generated method stub
           String amountvalue = amount.getText().toString();
           String ratevalue = rate.getText().toString();

           if (amountvalue.equals("") || ratevalue.equals("")) {
               val3 = 0d;
               val4 = 0d;
            } else {
               val3 = Double.parseDouble(amountvalue);
               val4 = Double.parseDouble(ratevalue);
            }

            System.out.println(Double.toString((double)val3/val4));    
            qty.setText(Double.toString((double)val3/val4));
        }
    });

logcat的

 java.lang.StackOverflowError
            at android.text.method.ReplacementTransformationMethod$ReplacementCharSequence.getChars(ReplacementTransformationMethod.java:151)
            at android.text.TextUtils.getChars(TextUtils.java:78)
            at android.text.TextUtils.indexOf(TextUtils.java:111)
            at android.text.StaticLayout.generate(StaticLayout.java:209)
            at android.text.DynamicLayout.reflow(DynamicLayout.java:324)
            at android.text.DynamicLayout.<init>(DynamicLayout.java:174)
            at android.widget.TextView.makeSingleLayout(TextView.java:6964)
            at android.widget.TextView.makeNewLayout(TextView.java:6813)
            at android.widget.TextView.checkForRelayout(TextView.java:7409)
            at android.widget.TextView.setText(TextView.java:4300)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$1.afterTextChanged(Delivery.java:93)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$2.afterTextChanged(Delivery.java:127)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$1.afterTextChanged(Delivery.java:93)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$2.afterTextChanged(Delivery.java:127)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$1.afterTextChanged(Delivery.java:93)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$2.afterTextChanged(Delivery.java:127)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$1.afterTextChanged(Delivery.java:93)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$2.afterTextChanged(Delivery.java:127)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView.java:4137)
            at android.widget.EditText.setText(EditText.java:104)
            at android.widget.TextView.setText(TextView.java:4112)
            at com.example.admin.foms.Delivery$1.afterTextChanged(Delivery.java:93)
            at android.widget.TextView.sendAfterTextChanged(TextView.java:8293)
            at android.widget.TextView.setText(TextView.java:4307)
            at android.widget.TextView.setText(TextView

Answer 1

根据this answer，为了避免在更改文本时递归，可以将标志设置为afterTextChanged方法，如下所示：

 boolean preventUpdate = false;

   @Override
   public void afterTextChanged(Editable s) {
      if(preventUpdate){
         preventUpdate = false; // reset flag after calling
         return;
      }

     // your logic 

        // prevent update after change value
        preventUpdate = true;   
        qty.setText(Double.toString((double)val3/val4));
   }

如果两个EdiText更改了彼此的文字，您应该添加另一个标记，以确保他们不会再次通知文本更改（考虑您的逻辑，无论何时您想使用{{1} } 方法）。

Answer 2

您已在TextWatcher（EditText和qty）上设置了amount，并且您在EditText上的候补TextChange上设置了文字。

更改amount EditText中的文字后，它会更改qty EditText中的值（因为TextWatcher），现在qty {{ 1}}值为更改，因此它会再次尝试更改EditText的值（因为amount EditText）并继续处理..并且出现 TextWatcher错误

Answer 3

你可以做点什么：

        // temporary disable the listener
        edt.removeTextChangedListener(this);
        // change the text
        edt.setText("Some text");
        // enable it again
        edt.addTextChangedListener(this);

Answer 4

stackoverflow的原因是由于TextWatcher（）而导致的无限循环，即EditTextA更改了w.r.t. EditTextB，反之亦然。因此，创建一个无限循环，堆栈会因函数的局部变量而耗尽。

解：

简单的解决方案是在当前文本和新文本相同时阻止更新。

qty.addTextChangedListener(new TextWatcher() {
    ...
    @Override
    public void afterTextChanged(Editable s) {
        if (qty.getText().toString().equals(s.toString())){return;}
        ...
    }
};

取消注册观察者，然后重新注册。 How can I change the EditText text without triggering the Text Watcher?
第三种解决方案是，您可以区分手动设置和以编程方式设置编辑文本。 EditText: Differentiate between text change by setText() or by keyboard input

Answer 5

在文本观察程序的最后一行中，将当前文本与要设置的文本进行比较。如果它们相同，则不要设置文本。这将避免无休止的循环。

使用Textwatcher时出现Stackoverflow错误

5 个答案: