android - addTextChangedListener 抛出 StackOverflow 错误

Question

我有这个代码:

areasqm.addTextChangedListener(new TextWatcher() {
    @Override
    public void afterTextChanged(Editable arg0) {
    }

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
    }

    @Override
    public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
        double val = Double.parseDouble(areasqm.getText().toString());
        areaha.setText(String.valueOf(val/10000));
    }      
});

areaha.addTextChangedListener(new TextWatcher() {
    @Override
    public void afterTextChanged(Editable arg0) {
    }

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
    }

    @Override
    public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
        double val = Double.parseDouble(areaha.getText().toString());
        areasqm.setText(String.valueOf(val*10000));
    }      
});

每当我在其中一个 EditText 中键入一个值时，我的应用程序就会崩溃并抛出 java.lang.StackOverflowError。

为什么？如何解决这个问题？

Answer 1

原因是:当您调用 areaha.setText(String.valueOf(val/10000)); 时，areaha 的 TextChangedListener 是触发并调用 areasqm.setText(String.valueOf(val*10000));，因此 areasqm 的 TextChangedListener 也被触发并调用 areaha.setText(String.valueOf(val/10000));。所以你有永恒的循环，结果是这个 java.lang.StackOverflowError.。

你可以尝试这样的事情。

private TextWatcher areasmlWatcher = new TextWatcher() {
    @Override
    public void afterTextChanged(Editable arg0) {
    }

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
    }

    @Override
    public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
        double val = Double.parseDouble(areasqm.getText().toString());
        areaha.removeTextChangedListener(areahaWatcher);
        areaha.setText(String.valueOf(val / 10000));
        areaha.addTextChangedListener(areahaWatcher);
    }
};

private TextWatcher areahaWatcher = new TextWatcher() {
    @Override
    public void afterTextChanged(Editable arg0) {
    }

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
    }

    @Override
    public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
        double val = Double.parseDouble(areaha.getText().toString());
        areasqm.removeTextChangedListener(areasmlWatcher);
        areasqm.setText(String.valueOf(val*10000));
        areasqm.addTextChangedListener(areasmlWatcher);
    }
};

private void someMethod() {
    areasqm.addTextChangedListener(areasmlWatcher);
    areaha.addTextChangedListener(areahaWatcher);
}