FATAL Exception got in Android

09-11 11:02:19.365: E/AndroidRuntime(1263): FATAL EXCEPTION: main
09-11 11:02:19.365: E/AndroidRuntime(1263): Process: com.nnk.program4, PID: 1263
09-11 11:02:19.365: E/AndroidRuntime(1263): java.lang.NumberFormatException: Invalid int: "+"
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at java.lang.Integer.invalidInt(Integer.java:137)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at java.lang.Integer.parse(Integer.java:374)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at java.lang.Integer.parseInt(Integer.java:365)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at java.lang.Integer.parseInt(Integer.java:331)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at com.nnk.program4.Calc$1.onClick(Calc.java:40)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at android.view.View.performClick(View.java:4438)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at android.view.View$PerformClick.run(View.java:18422)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at android.os.Handler.handleCallback(Handler.java:733)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at android.os.Handler.dispatchMessage(Handler.java:95)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at android.os.Looper.loop(Looper.java:136)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at android.app.ActivityThread.main(ActivityThread.java:5017)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at java.lang.reflect.Method.invokeNative(Native Method)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at java.lang.reflect.Method.invoke(Method.java:515)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
09-11 11:02:19.365: E/AndroidRuntime(1263): 	at dalvik.system.NativeStart.main(Native Method)

public class Calc extends Activity
{

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.calc);
		this.myLogin();
	}
	
	private EditText tx1,tx2,tx3;
	private Button b1;
	private TextView tv1;
	
	public void myLogin()
	{
		tx1 = (EditText)findViewById(R.id.editText1);
		tx2 = (EditText)findViewById(R.id.editText2);
		tx3 = (EditText)findViewById(R.id.editText3);
		b1 = (Button)findViewById(R.id.button1);
		tv1 =(TextView)findViewById(R.id.textView1);
		
		b1.setOnClickListener(new OnClickListener() {			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				
				int no1 = Integer.parseInt(tx1.getText().toString());
				int no2 = Integer.parseInt(tx3.getText().toString());
				System.out.println(no1+no2);
				String opt = tx2.getText().toString();
				System.out.println(opt);
				
				if (opt.equals("+")) {
					tv1.setText("Result : "+(no1+no2));
				} else {
					if (opt.equals("-")) {
					tv1.setText("Result : "+(no1-no2));
					} else {
						if (opt.equals("*")) {
							tv1.setText("Result : "+(no1*no2));
						} else {
							if (opt.equals("/")) {
								try {
									tv1.setText("Result : "+(no1/no2));	
								} catch (Exception e) {
									tv1.setText(e.getMessage());
								}								
							} else {
								tv1.setText("Sorry Wrong Operator");	
							}
						}
					}
				}
			}
		});
	}
}