Android IP地址验证

IP格式为四个三位数；且数字输入有严格限制。所以就要用到正则表达式判断。
MainActivity.java

public class MainActivity extends Activity {private EditText et1,et2,et3,et4;private Button btn;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        requestWindowFeature(getWindow().FEATURE_NO_TITLE);//隐藏标题栏        setContentView(R.layout.main);        et1=(EditText) findViewById(R.id.editText1);        et2=(EditText) findViewById(R.id.editText2);        et3=(EditText) findViewById(R.id.editText3);        et4=(EditText) findViewById(R.id.editText4);        btn=(Button) findViewById(R.id.button1);    }public void onClick(View v) {/*分别获取输入值*/    String string1=et1.getText().toString().trim();    String string2=et2.getText().toString().trim();    String string3=et3.getText().toString().trim();    String string4=et4.getText().toString().trim();    /*整合输入值*/    String string = string1 + "." + string2 + "." + string3 + "."            + string4;/*正则表达式*/    String ip = "(25[0-5]|2[0-4]\\d|1\\d{2}|[1-9]\\d|[1-9])\\."            + "(25[0-5]|2[0-4]\\d|1\\d{1,2}|\\d{2}|\\d)\\."            + "(25[0-5]|2[0-4]\\d|1\\d{1,2}|\\d{2}|\\d)\\."            + "(25[0-5]|2[0-4]\\d|1\\d{1,2}|\\d{2}|\\d)";//限定输入格式    Pattern p = Pattern.compile(ip);    Matcher m = p.matcher(string);    boolean b=m.matches();    if(string1.equals("")||string2.equals("")||string3.equals("")||string4.equals("")){        Toast.makeText(this, "IP地址不可为空!", Toast.LENGTH_LONG).show();    }    else{    if(b==false){        Toast.makeText(this, "IP格式输入错误", Toast.LENGTH_LONG).show();    }    else{    /*传值跳转*/    Intent intent = new Intent(MainActivity.this, IP.class);      intent.putExtra("ip", string);    startActivity(intent);    }    }}}

IP.java

public class IP extends Activity {    private TextView textView1;@Overridepublic void onCreate(Bundle savedInstanceState) {    // TODO Auto-generated method stub    super.onCreate(savedInstanceState);    setContentView(R.layout.number);    textView1=(TextView) findViewById(R.id.text1);    Intent intent=getIntent();    String s=intent.getStringExtra("ip");//接收输入的值    textView1.setText("IP为："+s+"");//重写textView，显示输入值}}