android中限制EditText最大输入字节数
16lz
2021-01-23
需求:用户只能在输入框内输入15个字节的字符(15个英文字符或5个中文字符)
了解:一个英文字符在Android中占一个字节,一个中文字符在Android中占3个字节代码
public class MainActivity extends AppCompatActivity { private EditText mEditText; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mEditText = (EditText) findViewById(R.id.etInput); mEditText.addTextChangedListener(new MyTextWatcher(this, mEditText, 15)); } private class MyTextWatcher implements TextWatcher { private Context context; private EditText editText; private int len; //允许输入的字节长度(一个中文占3个字节) public MyTextWatcher(Context context, EditText editText, int len) { this.context = context; this.editText = editText; this.len = len; } @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { } @Override public void onTextChanged(CharSequence s, int start, int before, int count) { } @Override public void afterTextChanged(Editable editable) { String inputStr = editable.toString().trim(); byte[] bytes = inputStr.getBytes(); if (bytes.length > len) { Toast.makeText(context, "超过规定字符数", Toast.LENGTH_SHORT).show(); Log.i("str", inputStr); //取前15个字节 byte[] newBytes = new byte[len]; for (int i = 0; i < len; i++) { newBytes[i] = bytes[i]; } String newStr = new String(newBytes); editText.setText(newStr); //将光标定位到最后 Selection.setSelection(editText.getEditableText(), newStr.length()); } } }}
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