TextInputLayout的使用

因为是design包下的，所以需要导包。

TextInputLayout是LinearLayout下的一个子类。 public class  TextInputLayout  extends  LinearLayout

布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.heima.textinputlayouttest.MainActivity">

    <android.support.design.widget.TextInputLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="账号" />
    </android.support.design.widget.TextInputLayout>

    <android.support.design.widget.TextInputLayout
        android:id="@+id/input"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="密码" />
    </android.support.design.widget.TextInputLayout>
</LinearLayout>

代码：

import android.support.design.widget.TextInputLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

    TextInputLayout input;

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

        input = (TextInputLayout) findViewById(R.id.input);
        EditText editText = input.getEditText();
        editText.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) {
                Log.e("itcast","afterTextChanged");
                if (s.length()>=10){
                    input.setErrorEnabled(true);
                    input.setError("字数不得超过10个");
                }else {
                    input.setErrorEnabled(false);
                }
            }
        });
    }
}

展示：