本文适合刚接触Android开发的读者 下面是详细代码：
package com.zhihuishu.myapplication;
import android.os.Bundle ;
import android.support.v7.app.AppCompatActivity ;
import android.view. View ;
import android.widget.Button ;
import android.widget.EditText ;
import android.widget.Toast ;
public class MainActivity extends AppCompatActivity {
EditText User_Name ;
EditText User_Pass ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState) ;
setContentView(R.layout. activity_main) ;
setTitle( "未注册") ; //设置标题
User_Name = (EditText) findViewById(R.id. User_Name) ; //获取控件中的内容
User_Pass = (EditText) findViewById(R.id. User_Pass) ;
Button Button_regist = (Button) findViewById(R.id. Button_regist) ;
Button_regist.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick( View view) {
if(!checkSN( User_Name.getText().toString().trim() , User_Pass.getText().toString().trim()) )
{
// Toast.makeText(MainActivity.this,"用户名或密码不能为空",Toast.LENGTH_SHORT).show();//弹框
}
}
}) ;
}
private boolean checkSN(String username , String sn) {
try {
if ((username == null) || (username.length() == 0)) {
Toast. makeText(MainActivity. this, "用户名不能为空" ,Toast. LENGTH_SHORT).show() ; //弹框
return false;
}
else if((sn == null) || (sn.length() == 0))
{
Toast. makeText(MainActivity. this, "密码不能为空" ,Toast. LENGTH_SHORT).show() ; //弹框
return false;
}
else if(username.equals( "123"))
{
Toast. makeText(MainActivity. this, "注册成功" ,Toast. LENGTH_SHORT).show() ; //弹框
}
else
{
Toast. makeText(MainActivity. this, "用户名或密码错误" ,Toast. LENGTH_SHORT).show() ; //弹框
}
} catch (Exception e) {
e.printStackTrace() ;
return false;
}
return true;
}
}