EditText:（登录案例）

XML：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical"
    android:layout_marginLeft="10dp"
    >
<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="EditText"
    android:gravity="center"
    android:textSize="20sp"
    android:textColor="@color/black"

    />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="left"
        android:text="账号："
        android:textSize="20sp"
        android:textColor="@color/black"

        />
<EditText
    android:id="@+id/et_account"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="请输入账号"
    android:textSize="20sp"
    android:textColor="@color/black"
    />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="left"
        android:text="密码："
        android:textSize="20sp"
        android:textColor="@color/black"
        />
    <EditText
        android:id="@+id/et_password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入密码"
        android:inputType="textPassword"
        android:textSize="20sp"
        android:textColor="@color/black"
        />
    <Button
        android:id="@+id/bt.login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="登录"
        android:layout_gravity="center"
        />
    <TextView
        android:id="@+id/tv_result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="left"
        android:hint="此处会显示登录的账号和密码："
        android:textSize="20sp"
        android:textColor="@color/black"

        />
</LinearLayout>

package com.example.myapplication2;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private Button mBTNLogin;
    private EditText mETPassword;
    private EditText mETAccount;
    private TextView mTVResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.edittext_layout);
    initView();
    mBTNLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            String account=mETAccount.getText().toString().trim();
            String password=mETPassword.getText().toString().trim();
//            mTVResult.setSingleLine(true);
//            mTVResult.setTextSize(24);
             mTVResult.setTextColor(Color.rgb(65,105,255));

            if(!account.isEmpty()&&!password.isEmpty())//字符串判断非空
            {
                mTVResult.setText("您输入的账号:"+account+"\n"+"您输入的密码:"+password);
            }
            else{

               Toast toast= Toast.makeText(MainActivity.this, "请输入账号或密码", Toast.LENGTH_LONG);

                toast.show();
                //底部提示信息
            }
        }
    });
    mETAccount.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) {

        }

        @Override
        public void afterTextChanged(Editable editable) {
            String account=mETAccount.getText().toString().trim();
            String password=mETPassword.getText().toString().trim();
            mTVResult.setText("您输入的账号:"+account+"\n"+"您输入的密码:"+password);


        }
    });
       mETPassword.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) {

            }
            @Override
            public void afterTextChanged(Editable editable) {
                String account=mETAccount.getText().toString().trim();
                String password=mETPassword.getText().toString().trim();
                mTVResult.setText("您输入的账号:"+account+"\n"+"您输入的密码:"+password);
            }
        });

    }
    private void initView()
    {
        mETAccount = findViewById(R.id.et_account);
        mETPassword = findViewById(R.id.et_password);
        mBTNLogin = findViewById(R.id.bt_login);
        mTVResult = findViewById(R.id.tv_result);

    }

}

效果图: