用户输入时更改TextInputLayout的Hint值

Question

这是我TextInputEditText中的TextInputLayout。您可以看到的提示已设置在TextInputLayout上。

用户必须写 255个字符，否则该帖子无效。

我希望数字 255 随着用户的输入而减少，当达到0时，提示应该为空白。

这是我的代码：

private int charactersLeft = 256;在onCreate方法外部声明。

这段代码在onCreate方法内部：

final TextInputLayout postTextInputBase = findViewById(R.id.post_text_input_base);

final TextInputEditText postTextInput = findViewById(R.id.post_text_input);

postTextInput.addTextChangedListener(new TextWatcher() {

    @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 (charactersLeft == 0) {
            postTextInputBase.setHint(null);
        } else {
            postTextInputBase.setHint((charactersLeft - 1) + " characters left");
        }
    }

    @Override
    public void afterTextChanged(Editable s) {

    }
});

我还尝试将charactersLeft设置为characterLeft -= 1，但是java不允许我这样做。

然后，我该怎么做？

Answer 1

使用app:counterEnabled="true"

• 在此布局中是否启用了字符计数器功能。

也使用app:counterMaxLength="250"

• 设置要在字符计数器上显示的最大长度。

尝试一下

<android.support.design.widget.TextInputLayout
    android:id="@+id/post_text_input_base"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:counterEnabled="true"
    app:counterMaxLength="250">

    <EditText
        android:id="@+id/post_text_input"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="UserName" />
</android.support.design.widget.TextInputLayout>

输出

编辑

public class RecyclerViewActivity extends AppCompatActivity {

    TextInputLayout postTextInputBase;
    EditText postTextInputEditText;

    int textLength = 9;
    int len = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recycler_view);

        postTextInputBase = findViewById(R.id.post_text_input_base);

        postTextInputEditText = findViewById(R.id.post_text_input);

        postTextInputBase.setHint(textLength + " characters left");

        postTextInputEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

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

                // first check your EditText is empty or not
                if (!TextUtils.isEmpty(postTextInputEditText.getText().toString())) {

                    int len = postTextInputEditText.getText().toString().length();
                    // than check that editText text length is less than max length or not
                    // for test case i have set max length 10
                    if (len < 9) {
                        // if length of text is less than max length than use minus one from max length and set error in your text input layout
                        textLength--;
                    } else {
                        textLength++;

                    }

                    postTextInputBase.setHint(textLength + " characters left");
                } else {
                    textLength = 9;
                }
            }

            @Override
            public void afterTextChanged(Editable s) {

              if(postTextInputEditText.getText().toString().isEmpty()){
                  textLength = 9;
                  postTextInputBase.setHint(textLength + " characters left");
              }
            }
        });


    }


}

输出

编辑2如果您需要设置提示而不是使用此提示

postTextInputBase.setHint(textLength + " characters left");

输出

  

注意，不要忘记在edittext中设置 android:maxLength="10"

Answer 2

尝试一下。使用您现有的代码。

int charactersLeft = 256;
final TextInputLayout postTextInputBase = findViewById(R.id.post_text_input_base);
final TextInputEditText postTextInput = findViewById(R.id.post_text_input);

postTextInput.addTextChangedListener(new TextWatcher() {

        @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 s) {
           if (s.length() == 0) {
                postTextInputBase.setHint(null);
            }else {
                postTextInputBase.setHint((charactersLeft - s.length()) + " characters left");
            }
        }
    });

并将android:maxLength="256"添加到您的TextInputEditText

Answer 3

您可以在编辑文本上使用setOnKeyListener以编程方式进行操作。

TextInputLayout postTextInputBase = findViewById(R.id.post_text_input_base);
TextInputEditText postTextInput = findViewById(R.id.post_text_input);
postTextInput.setOnKeyListener((v, keyCode, event) -> {
        // Do other things needed
        postTextInputBase.setHint("Characters left: " + (256 - postTextInput.getText().length()));
        return false;
});

Answer 4

要仅更改提示文本，只需将焦点更改即可。

editText.setOnFocusChangeListener(new View.OnFocusChangeListener() {
        @Override
        public void onFocusChange(View v, boolean hasFocus) {
            if(hasFocus)
                editText.setHint("Enter name");
            else
                editText.setHint("Name");
        }
    });