运行Android应用程序

Question

我有麻烦时，我试图运行我的简单的Android应用程序在我的系统 我为这是不是我的系统上创建和那些行之有效的一些其他应用程序进行测试，但是当我编辑的我的系统上那么这些应用程序也不会工作。我收到了许多错误

09-26 07:23:55.458: E/AndroidRuntime(1341):  ... 11 more 
    at com.calculation.MainActivity.<init>(MainActivity.java:19) 
    at java.lang.Class.newInstanceImpl(Native Method) 
: at java.lang.Class.newInstance(Class.java:1130) 
    at android.app.Instrumentation.newActivity(Instrumentation.java:1061) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128) 

为什么会出现这种 请帮我

package com.calculation; 

import android.os.Bundle; 
import android.app.Activity; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 
import android.widget.Toast; 
import android.app.AlertDialog; 
import android.content.DialogInterface; 

public class MainActivity extends Activity { 

    EditText value1,value2; 
    Button add; 
    TextView display; 
    int num1=0, num2=0, total=0; 
    final AlertDialog alertdialog= new AlertDialog.Builder(MainActivity.this).create(); 
    @SuppressWarnings("deprecation") 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     value1=(EditText)findViewById(R.id.input1); 
     value2=(EditText)findViewById(R.id.input2); 
     add=(Button)findViewById(R.id.btnadd); 
     display=(TextView)findViewById(R.id.result); 
     if(value1==null) 
     { 
      alertdialog.setTitle("AlertDialog"); 
      alertdialog.setMessage("Please Enter a Valid Input"); 
      alertdialog.setIcon(R.drawable.ic_launcher); 
      alertdialog.setButton("Ok", new DialogInterface.OnClickListener() { 

       @Override 
       public void onClick(DialogInterface dialog, int which) { 
        // TODO Auto-generated method stub 
        Toast.makeText(getApplicationContext(), "You Clicked OK" , Toast.LENGTH_LONG).show(); 
       } 
      }); 
     } 
     else if(value2==null) 
     { 
      alertdialog.setTitle("AlertDialog"); 
      alertdialog.setMessage("Please Enter a Valid Input"); 
      alertdialog.setIcon(R.drawable.ic_launcher); 
alertdialog.setButton("Ok", new DialogInterface.OnClickListener() { 

       @Override 
       public void onClick(DialogInterface dialog, int which) { 
        // TODO Auto-generated method stub 
        Toast.makeText(getApplicationContext(), "You Clicked OK" , Toast.LENGTH_LONG).show(); 
       } 
      }); 
     } 
      add.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 
       // TODO Auto-generated method stub 

       num1=Integer.parseInt(value1.getText().toString()); 
       num2=Integer.parseInt(value2.getText().toString()); 
       total=num1+num2; 
       display.setText("ADDITION IS"+total); 
      } 
     }); 


    } 

}

Answer 1

问题是API级别的被测试的应用程序是在创造了许多年前不同的API水平和环境，以便警告对话框中的错误是未来 警告对话框可以用这种方式

private void showinvalidemail() { 
     // TODO Auto-generated method stub 
     AlertDialog.Builder dialogbuilder = new AlertDialog.Builder(this); 
     dialogbuilder.setTitle("Invalid Email"); 
     dialogbuilder.setMessage("Please Enter Valid Email"); 
     dialogbuilder.setIcon(R.drawable.mexit); 
     dialogbuilder.setPositiveButton("Ok", 
       new DialogInterface.OnClickListener() { 

        @Override 
        public void onClick(DialogInterface arg0, int arg1) { 
         // TODOAuto-generated method stub 
         Toast.makeText(getApplicationContext(), 
           "You Clicked OK", Toast.LENGTH_LONG).show(); 
        } 
       }); 
     AlertDialog alertdialog = dialogbuilder.create(); 
     alertdialog.show(); 
    }