例如，我有两个字符的长度限制的 EditText。当输入第一个和第二个字母时就可以了。但是当我们尝试输入第三个字母时，第一个字母应该用它代替。下一个字母应替换第二个字母，以此类推。我该怎么做。
【问题讨论】：
试试这个
editText.addTextChangedListener(new TextWatcher() {
private int charLimit = 5;
private int position = 5;
private String newSequence;
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (s.length() > charLimit ) {
if (position == charLimit) {
newSequence = s.subSequence(s.length()-1, s.length()).toString() +
s.subSequence(1, charLimit);
position = 1;
} else {
position++;
newSequence = s.subSequence(0, position).toString() +
s.subSequence(position+1, s.length());
}
editText.setText(null);
editText.setText(newSequence);
editText.setSelection(position);
}
}
@Override
public void afterTextChanged(Editable s) {
}
});
【讨论】：
尝试在编辑文本上使用 TextWatcher 以实现目标
editText.addTextChangedListener(new TextWatcher() {
private int lastModifiedIndex = 1;
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (s.length() > 2) {
char toReplace = s.charAt(s.length() - 1);
if (lastModifiedIndex == 0) {
editText.setText("" + s.charAt(lastModifiedIndex) + toReplace);
lastModifiedIndex = 1;
editText.setSelection(s.length());
} else {
editText.setText("" + toReplace + s.charAt(lastModifiedIndex));
lastModifiedIndex = 0;
editText.setSelection(s.length());
}
} else {
lastModifiedIndex = 1;
}
}
@Override
public void afterTextChanged(Editable s) {
}
});
【讨论】：