Android 重新登录时应用程序崩溃

我正在创建一个android USB主机应用程序，它包含登录页面，当我第一次登录时，它成功登录，当我按“上一步”按钮并再次转到登录页面时，我按下“登录”按钮，然后我的应用程序崩溃…请帮我解决此问题

这是我的java代码：

import java.nio.ByteBuffer;
import java.util.HashMap;
import android.annotation.SuppressLint;
import android.app.ActionBar;
import android.app.Activity;
import android.content.Intent;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbDeviceConnection;
import android.hardware.usb.UsbEndpoint;
import android.hardware.usb.UsbInterface;
import android.hardware.usb.UsbManager;
import android.hardware.usb.UsbRequest;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.example.demo2c1testpanel.LifeTest;
import com.example.demo2c1testpanel.DriveResponseTest;

public class Loginpage extends Activity
{

    public static final int targetVendorID = 1155;      
    public static final int targetProductID = 22336;
    public  UsbManager manager;
    public  UsbDeviceConnection usbDeviceConnection;
    public  UsbInterface usbInterfaceFound = null;
    public  UsbEndpoint endpointOut = null;
    public  UsbEndpoint endpointIn = null;
    public  UsbDevice usbdevice,device_details;
    public  UsbEndpoint listusbendpoint;
    public LifeTest Life_Test_child;
    HashMap<String, UsbDevice> devicelist= null;
    int selectedendpoint; 
    static int Coil_No;
    private static final int VID = 1155;
    private static final int PID = 22336;
    private static UsbDriver Usb_Driver_class;
    ActionBar actionbar;
    UsbConnectionHandler connectionHandler;
    public static UsbDriver USB_Driver_Child;
    public static boolean Communication_Failed,Frame_Ok,Total_Frame_Decoded;
    static byte[] Communication_Byte;
    Button clear,signin;
    EditText username,password;
    String i = "";
    Intent i2;
    String User_Name=null;
    TextView title;
    ByteBuffer buffer;
    static byte[] sample;
    static boolean Communication_Ok;
    public static float []Wave_Form_Data=new float[1500];
    public static float []Wave_Form_Data_1=new float[1500];
    public static float Respsonse_Time,Drive_Voltage;
    static int Sequence_No,Response_Time;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.loginpage);
        actionbar = getActionBar();
        actionbar.hide();
        username = (EditText)findViewById(R.id.edt_username);
        password = (EditText)findViewById(R.id.edt_password);
        title = (TextView)findViewById(R.id.textView1);
        title.setSelected(true);
        signin = (Button)findViewById(R.id.btn_signin);
        signin.setOnClickListener(new View.OnClickListener() {

            @SuppressWarnings("static-access")
            @Override
            public void onClick(View v) 
            {
                {
                    Communication_Byte=new byte[1];
                    User_Name=username.getText().toString();
                    if(User_Name.toLowerCase().equals("medequip") && password.getText().toString().equals("medequip"))
                    {
                        if(Check_Devices_Available()==true)
                        {   
                            int Packet_Size = USB_Driver_Child.Data_In_End_Point.getMaxPacketSize();
                            Toast.makeText(Loginpage.this,""+Packet_Size, Toast.LENGTH_LONG).show();
                            Receive.start();
                            Communication_Ok=false;
                            for(int i=0;(i<5 && Communication_Ok!=true);i++)    
                            Send_Communication_Check_Command();

                            if(Communication_Ok)
                                Toast.makeText(Loginpage.this, "Communication Successfully Established", 1000).show();
                            else
                                Toast.makeText(Loginpage.this, "Communication Failure", 10000).show();

                            i2 = new Intent(Loginpage.this,TestsPage.class);
                            startActivity(i2);
                        }

                    }
                    else
                    {
                        Toast.makeText(Loginpage.this,"Invalid username and password", Toast.LENGTH_LONG).show();
                    }

                }
              }     
            });

        clear = (Button)findViewById(R.id.btn_clear);
        clear.setOnClickListener(new View.OnClickListener()
        {

            @Override
            public void onClick(View v)
            {

            username.setText("");
            password.setText("");

            }
        });

         }


    @SuppressLint("ShowToast") @SuppressWarnings({ "static-access" })
    public boolean  Check_Devices_Available() 
    {
        Usb_Driver_class = new UsbDriver(this, connectionHandler, VID, PID);

        if(USB_Driver_Child.Device_Exception==0)
        {

            if(USB_Driver_Child.USB_Device_Connection==null || USB_Driver_Child.Data_Out_End_Point==null)
            return false;   

            Toast.makeText(Loginpage.this,"Device Found", 1000).show(); 
            return true;
        }
        else if(USB_Driver_Child.Device_Exception==1)
        {
            Toast.makeText(Loginpage.this,"No Devices Attached ", Toast.LENGTH_LONG).show();    
            return false;
        }
        else if(USB_Driver_Child.Device_Exception==2)
        {
            Toast.makeText(Loginpage.this,"Device Found,But No End Points", Toast.LENGTH_LONG).show();  
            return false;
        }
        else if(USB_Driver_Child.Device_Exception==3)
        {
            Toast.makeText(Loginpage.this,"Unable to Open Device", Toast.LENGTH_LONG).show();   
            return false;
        }
        return false;   //un known exception
    }

Thread Receive  = new Thread(new Runnable()
    {

    @SuppressWarnings("unused")
    @Override
    public void run() 
    {
        Sequence_No=0;
        buffer = ByteBuffer.allocate(1500);
        sample = new byte[1500];
        int Frame_Size;
        UsbRequest request = new UsbRequest();
        int i,j;
        byte [] datarx=new byte[1]; 
        char q;
        while (true) 
        {
        request.initialize(UsbDriver.USB_Device_Connection, UsbDriver.Data_In_End_Point);
        request.queue(buffer, 1500);
        if (UsbDriver.USB_Device_Connection.requestWait() == request) 
        {
                sample=buffer.array(); 
                for(i=0;i<1500;i++)
                {
                        if(sample[i]=='&')
                        {
                            Communication_Ok=true;
                            break;
                        }
                        else if(sample[i]==0x03)
                        {
                            if(sample[0]==0x02)
                            Frame_Ok=true;  
                            break;
                        }

                }
                if(Frame_Ok==true)
                {
                    Frame_Ok=false;
                    if(sample[1]==1)
                    Coil_No=1;
                    else
                    Coil_No=2;
                    Response_Time= (int)(((sample[2]&0x00FF)<<8) + (sample[3]&0x00FF));

                    Total_Frame_Decoded=true;
                    sample = null;
                }   
        }
      }
    }
  });


private static void Send_Communication_Check_Command() 
{
    long i,j;

    Communication_Byte[0]='&';
    UsbDriver.USB_Device_Connection.bulkTransfer(UsbDriver.Data_Out_End_Point,Communication_Byte, 1, 0);
    for(i=0;(i<1000 && Communication_Ok!=true) ;i++)    
    for(j=0;(j<1000 && Communication_Ok!=true);j++);
}
//Test_Name=1; For Drive Response Test
//Test_Name=2; For Drive Life Test
//Test_Name=3; To Stop test 

public static void Send_Command_For_Drive_Response_Test(int Test_Name)
{
    int i;
    byte []Command_To_Transfer= new byte[5];
    Communication_Ok=false;
    for(i=0;i<5;i++)
    {   
        Send_Communication_Check_Command();
        if(Communication_Ok==true)
        break;  
    }
    if(Communication_Ok==true)
    {
        Command_To_Transfer[0]='*';
        if(Test_Name==1)
        {
            Command_To_Transfer[1]=Command_To_Transfer[2]=(byte) 0xA1;
        }
        else if(Test_Name==2)
        {
            Command_To_Transfer[1]=Command_To_Transfer[2]=(byte) 0xA2;
        }
        else if(Test_Name==3)
        {
            Command_To_Transfer[1]=Command_To_Transfer[2]=(byte) 0xA3;
        }
        Command_To_Transfer[3]=0; //For Future Reference 
        Command_To_Transfer[4]='#';
        UsbDriver.USB_Device_Connection.bulkTransfer(UsbDriver.Data_Out_End_Point,Command_To_Transfer, 5, 0);
        Communication_Failed=true;
    }
    else
    {
        Communication_Failed=false;
    }
}



}

---

我必须检查线程状态。这是我在接收线程的工作代码

if(!Receive.isAlive())
{
    Receive.start();
}

---

显示进度警报并禁用

登录

按钮单击，直到第一次单击事件未完成。问题是由于对已声明的线程调用了

start

方法导致的。我如何停止线程的可能副本的可能副本。我可以在何处停止线程@ρƏσѕρєK@Sundeep：要停止线程，请在run方法中使用

布尔

标志。看见

01-05 06:17:51.794: W/dalvikvm(6120): threadid=1: thread exiting with uncaught exception (group=0x41994700)
01-05 06:17:51.804: E/AndroidRuntime(6120): FATAL EXCEPTION: main
01-05 06:17:51.804: E/AndroidRuntime(6120): java.lang.IllegalThreadStateException: Thread already started
01-05 06:17:51.804: E/AndroidRuntime(6120):     at java.lang.Thread.checkNotStarted(Thread.java:871)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at java.lang.Thread.start(Thread.java:1025)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at com.example.demo2c1testpanel.Loginpage$2.onClick(Loginpage.java:89)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at android.view.View.performClick(View.java:4240)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at android.view.View$PerformClick.run(View.java:17721)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at android.os.Handler.handleCallback(Handler.java:730)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at android.os.Handler.dispatchMessage(Handler.java:92)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at android.os.Looper.loop(Looper.java:137)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at android.app.ActivityThread.main(ActivityThread.java:5103)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at java.lang.reflect.Method.invokeNative(Native Method)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at java.lang.reflect.Method.invoke(Method.java:525)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
01-05 06:17:51.804: E/AndroidRuntime(6120):     at dalvik.system.NativeStart.main(Native Method)

if(!Receive.isAlive())
{
    Receive.start();
}