为什么这个简单的Android应用程序是递归的？

Question

这里有新的SO用户,相当新的Java.运行此命令时,它会因java.lang.stackoverflow错误而崩溃.我很确定它是递归的,但我无法弄清楚为什么.我已经尝试逐步调试但是我收到一个错误,它无法找到类文件.这是代码:

 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    newPrice.addTextChangedListener(tradeWatch);
    tradeIn.addTextChangedListener(tradeWatch);
    acc.addTextChangedListener(tradeWatch);
    tradeDif.addTextChangedListener(tradeWatch);

}

TextWatcher tradeWatch = new TextWatcher() {

    @Override
    public void afterTextChanged(Editable s) {
        calcTrade();

    }

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

    }

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

    }

};

private void calcTrade() {
Editable eValue1 = newPrice.getText(), eValue2 = tradeIn.getText(), eValue3 = acc.getText();
Double value1 = 0.0, value2 = 0.0, value3 = 0.0, result = 0.0;

if (eValue1 != null)
    value1 = toDouble(eValue1);
if (eValue2 != null)
    value2 = toDouble(eValue2);
if (eValue3 != null)
    value3 = toDouble(eValue3);
if (value1 != null && value2 != null && value3 != null)
    result = value1 - (value2 + value3);
    tradeDif.setText(result.toString());

}
private double toDouble(final Editable editable) {
    final String content = editable.toString();
    if (content.isEmpty()) {
        return 0;
    }
    return Double.parseDouble(content);
}

public void nextPage(View v) {
    Intent i=new Intent(this, Activity2.class);
    startActivity(i);
}


}

Answer 1

问题是线:

tradeDif.setText(result.toString());

您更改文本并导致调用

afterTextChanged(Editable s) 

一次又一次.

简单解决方案

1. 删除监听器
2. 改变价值
3. 添加监听器