如何使用 TextWatcher 在 EditText 上获取新输入的值

Question

我可以得到旧值。但我没有解决方案来获得新的输入 值。

其实，我想把旧值和新值分开。 例如：如果 oldText=hello 和新输入的 EditText 值等于（hello w 或 w hello），我想要 newText=w.

public class MyTextWatcher implements TextWatcher {


    private String oldText = "";
    private String newText = "";

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        this.oldText = s.toString();
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

    @Override
    public void afterTextChanged(Editable s) {

    }

}

感谢您的帮助。

Answer 1

试试这个代码：

public class MyTextWatcher implements TextWatcher {


    private String oldText = "";
    private String newText = "";

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        this.oldText = s.toString();
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        newText = s.toString().replace(oldText, "").trim();
    }

    @Override
    public void afterTextChanged(Editable s) {

    }

}

关于文本观察器的信息： Differences between TextWatcher 's onTextChanged, beforeTextChanged and afterTextChanged

Answer 2

通过start和count参数在onTextChanged方法中，可以计算得到新的输入值。

onTextChanged

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. It is an error to attempt to make changes to s from this callback.

所以你可以：

public class MyTextWatcher implements TextWatcher {

    private String newTypedString = "";

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

    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        newTypedString = s.subSequence(start, start + count).toString().trim();
    }

    @Override
    public void afterTextChanged(Editable s) {

    }

}