小白开发安卓程序之路（2-4）EditText（常用属性、监听事件、登录界面）

小知识

1. activity_main.xml中给button加上textAllCaps属性设为false，就不会全大写了。
2. Button里的字默认居中。
3. 注意打印字符串时的变量名

实战

代码中用到两张图片需要提前存到相应文件夹

代码

MainActivity.java

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    private Button mbtnTextView;
    private Button mbtnButton;
    private  Button mbtnEditText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mbtnTextView=findViewById(R.id.btn_textview);
        mbtnTextView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //跳转至TextView演示界面
                Intent intent=new Intent(MainActivity.this,TextViewActivity.class);
                startActivity(intent);
            }
        });
        mbtnTextView=findViewById(R.id.btn_button);
        mbtnTextView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //跳转到Button演示界面
                Intent intent=new Intent(MainActivity.this,ButtonActivity.class);
                startActivity(intent);
            }


        });
        mbtnEditText=findViewById(R.id.btn_edittext);
        mbtnEditText.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //跳转到Button演示界面
                Intent intent=new Intent(MainActivity.this,EditTextActivity.class);
                startActivity(intent);
            }
        });
    }
}

activity_main.xml

<?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"
    tools:context=".MainActivity"
    android:orientation="vertical">
    <Button
        android:id="@+id/btn_textview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="TextView"
        android:textAllCaps="false"/>
    <Button
        android:id="@+id/btn_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Textbutton"
        android:textAllCaps="false"/>
    <Button
        android:id="@+id/btn_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="EditText"
        android:textAllCaps="false"/>
        <!--textAllCaps即内容全部大写    -->

</LinearLayout>

EditTextActivity.java

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class EditTextActivity extends AppCompatActivity {
    private Button mbtnLogin;
    private EditText mEtUserName;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_edit_text);
        mbtnLogin=findViewById(R.id.btn_login);
        mbtnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(EditTextActivity.this,"登录成功",Toast.LENGTH_LONG).show();
            }
        });
        mEtUserName=findViewById(R.id.et_1);
        mEtUserName.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                Log.d("edittext",charSequence.toString());
                //监听输入内容并输出（在logcat可以看到）
            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        });
    }
}

activity_edit_text.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="10dp">
    <EditText
        android:id="@+id/et_1"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:textSize="20sp"
        android:textColor="#FFAAAA"
        android:hint="用户名"
        android:background="@drawable/bg_username"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"
        android:drawableLeft="@drawable/icon_user"
        android:drawablePadding="5dp"
        android:maxLines="1"
        android:layout_marginTop="50dp"/>
    <!--hint灰色提示文字
       用background设置框框格式为描边
       padding设置类边距 不然文字太靠边
       margintop设置与最上面的距离
       drawableLeft 在左侧放置一个drawable文件（这里是一个icon图标）
       drawablePadding 设置图标与文字间隔
       maxlines限制最大行数-->
    <EditText
        android:id="@+id/et_2"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:textColor="#AACC22"
        android:textSize="20sp"
        android:hint="密码"
        android:inputType="textPassword"
        android:layout_below="@id/et_1"
        android:background="@drawable/bg_username"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"
        android:drawableLeft="@drawable/icon_password"
        android:drawablePadding="5dp"
        android:maxLines="1"/>
    <!--inputType=textPassword 密码隐藏 inputType=number就是弹出数字键盘    -->
    <Button
        android:id="@+id/btn_login"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:layout_below="@id/et_2"
        android:layout_marginTop="30dp"
        android:background="@drawable/bg_btn_4"
        android:text="登录"
        android:textColor="#000000"
        android:textSize="20sp" />
    <!--background用了按压会变色的drawable
    在EditTextActivity.java中为这个按钮添加了点击事件，会弹出“登录成功” -->


</RelativeLayout>

bg_username.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <!--    矩形-->
    <stroke
        android:width="1dp"
        android:color="#878282"/>
    <!--    描边-->
    <corners
        android:radius="8dp"/>
    <!--    圆角-->
</shape>

bg_btn_4.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape>
            <solid android:color="#2A9FAE"/>
            <corners android:radius="5dp"/>
        </shape>
    </item>
    <!--按压时    -->
    <item android:state_pressed="false">
        <shape>
            <solid android:color="#79EDFD"/>
            <corners android:radius="5dp"/>
        </shape>
    </item>
    <!--未按压    -->


</selector>

效果

本文地址：https://blog.csdn.net/weixin_45941945/article/details/107418545