andriod 用户名和密码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="3dip"
    >

<!--0固定1可以扩展-->

    <TableLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:numColumns="8"
        android:shrinkColumns="0"
        android:stretchColumns="1">

        <TableRow
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">

            <TextView
                android:id="@+id/label"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="请输入用户名：" />
            <!-- 这个EditText放置在上边id为label的TextView的下边 -->
            <EditText
                android:id="@+id/username"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@id/label"
                android:background="@android:drawable/editbox_background" />

        </TableRow>
        <TableRow>

            <TextView
                android:id="@+id/label1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="密码：" />
            <!-- 这个EditText放置在上边id为label的TextView的下边 -->
            <EditText
                android:id="@+id/pass"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@id/label1"
                android:inputType="textPassword"
                android:background="@android:drawable/editbox_background" />
            <CheckBox
                android:id="@+id/checkBox1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="显示密码" />

        </TableRow>

        <TableRow
            android:layout_width="wrap_content"
            android:layout_height="match_parent">
            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="确定"
                android:id="@+id/ok"
                android:layout_column="1"
                android:layout_span="1" />
            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="取消"
                android:id="@+id/cancel"
                android:layout_column="1" />

        </TableRow>

    </TableLayout>

</LinearLayout>

package com.example.yanlei.mytk;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.method.HideReturnsTransformationMethod;
import android.text.method.PasswordTransformationMethod;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private TextView passEdit;
    private TextView userNameEdit;
    private CheckBox checkBox1;
    private Button btnok;
    private Button btncancel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        passEdit = (TextView) findViewById(R.id.pass);
        userNameEdit = (TextView) findViewById(R.id.username);
        checkBox1 = (CheckBox) findViewById(R.id.checkBox1);
        btnok = (Button) findViewById(R.id.ok);
        btncancel = (Button) findViewById(R.id.cancel);

        btncancel.setOnClickListener(new ButtonexitClickListener());
        btnok.setOnClickListener(new ButtonokClickListener());
        checkBox1.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                // TODO Auto-generated method stub
                if (isChecked) {
                    //如果选中，显示密码
                    passEdit.setTransformationMethod(HideReturnsTransformationMethod.getInstance());
                } else {
                    //否则隐藏密码
                    passEdit.setTransformationMethod(PasswordTransformationMethod.getInstance());
                }

            }
        });

    }

    private class ButtonexitClickListener implements View.OnClickListener {

        public void onClick(View v) {
            System.exit(0);

        }

    }

    private class ButtonokClickListener implements View.OnClickListener {

        public void onClick(View v) {
            String UserName = userNameEdit.getText().toString();
            String pass = passEdit.getText().toString();
            Toast toast;

            if (UserName.equals("YL") && pass.equals("123")) {
                toast = Toast.makeText(getApplicationContext(), "密码正确" + UserName + ":" + pass, Toast.LENGTH_LONG);

            } else {
                toast = Toast.makeText(getApplicationContext(), "密码错误" + UserName + ":" + pass, Toast.LENGTH_LONG);
            }
            toast.show();

        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

优化界面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="3dip">

    <!--0固定1可以扩展-->

    <TableLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:numColumns="8"
        android:shrinkColumns="0"
        android:stretchColumns="1">

        <TableRow
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">

            <TextView
                android:id="@+id/label"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="请输入用户名：" />
            <!-- 这个EditText放置在上边id为label的TextView的下边 -->
            <EditText
                android:id="@+id/username"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@id/label"
                android:background="@android:drawable/editbox_background" />

        </TableRow>

        <TableRow>

            <TextView
                android:id="@+id/label1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="密码：" />
            <!-- 这个EditText放置在上边id为label的TextView的下边 -->
            <EditText
                android:id="@+id/pass"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@id/label1"
                android:background="@android:drawable/editbox_background"
                android:inputType="textPassword" />

            <CheckBox
                android:id="@+id/checkBox1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="显示密码" />

        </TableRow>

        <TableRow
            android:layout_width="wrap_content"
            android:layout_height="match_parent">

        </TableRow>

    </TableLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="5dip"
        android:gravity="right"
        android:weightSum="1">

        <Button
            android:id="@+id/ok"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="0.20"
            android:text="确定"
            android:layout_marginRight="20dip" />

        <Button
            android:id="@+id/cancel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="取消"
            android:layout_weight="0.20"
            android:hint="退出"

            android:clickable="true" />
    </LinearLayout>
</LinearLayout>

=======================================================

又一个登陆界面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAlignment="center"
        android:text="用户登录界面"

        android:autoText="false"
        android:gravity="center" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="用户名    :" />

        <EditText
            android:id="@+id/editText1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="请输入用户名" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:text="密        码:" />

        <EditText
            android:id="@+id/editText2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="请输入密码"
            android:layout_weight="1"
            android:inputType="textPassword" />

        <CheckBox
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="显示密码"

            android:id="@+id/checkBox" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/btn_confirm"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"

            android:text="确认" />

        <Button
            android:id="@+id/btn_back"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"

            android:text="返回" />
    </LinearLayout>

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"

        android:id="@+id/imageView"
        android:layout_gravity="center_horizontal" />

</LinearLayout>