Question

我的应用程序有一个输入，用户可以输入端口号，我尝试输入超过9位数的好奇心（例如：1234567890），应用程序将崩溃。如何防止它崩溃？< / p>

修改我正在使用Android的Java语言

编码

public class addActivity extends Activity{

  EditText savedName,savedIP,savedPort,savedUserID,savedUserPass,savedChannel;
  Button btnSave;
  Button btnBack;
  String addressList;
  FileOutputStream outputStream;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add);

savedName = (EditText)findViewById(R.id.editName);
savedIP = (EditText)findViewById(R.id.editIP);
savedPort = (EditText)findViewById(R.id.editPort);
savedUserID = (EditText)findViewById(R.id.userID);
savedUserPass = (EditText)findViewById(R.id.userPass);
savedChannel = (EditText)findViewById(R.id.editChannel);
btnSave = (Button)findViewById(R.id.btnSave);
btnBack = (Button)findViewById(R.id.btnBack);


try{
     String channelNumString = savedChannel.getText().toString();
     int channelNum = Integer.parseInt(String.valueOf(channelNumString));

     addressList = savedName.getText().toString();

        outputStream = openFileOutput(addressList, Context.MODE_PRIVATE);
        //outputStream.write(savedName.getText().toString().getBytes());
        outputStream.write("4-".getBytes());
        outputStream.write(savedIP.getText().toString().getBytes());
        outputStream.write(":".getBytes());
        outputStream.write(savedPort.getText().toString().getBytes());
        outputStream.write("/user=".getBytes());
        outputStream.write(savedUserID.getText().toString().getBytes());
        outputStream.write("&password=".getBytes());
        outputStream.write(savedUserPass.getText().toString().getBytes());
        outputStream.write(System.getProperty("line.separator").getBytes());
        outputStream.close();
        Toast.makeText(getBaseContext(), "Address Saved !", Toast.LENGTH_SHORT).show();
        savedName.setText("");
        savedIP.setText("");
        savedPort.setText("");
        savedUserID.setText("");
        savedUserPass.setText("");
        savedChannel.setText("");

else{
        Toast.makeText(getBaseContext(),"Apps does not support " + channelNumString + " channels",Toast.LENGTH_LONG).show();
      }
 }catch (Exception e){
      e.printStackTrace();
    }

布局

<EditText
        android:layout_width="350dp"
        android:layout_height="wrap_content"
        android:id="@+id/editChannel"
        android:background="@android:drawable/edit_text"
        android:maxLines="1"
        android:layout_gravity="center_horizontal"
        android:inputType="number"
        android:digits="0123456789."/>

这是我在

遇到问题的部分

Answer 1

我假设你正在使用EditText。所以你需要使用addTextChangedListener()。

尝试以下方式，

YOUR_EDIT_TEXT.addTextChangedListener(new TextWatcher() 
          {
               public void afterTextChanged(Editable s) {}
               public void beforeTextChanged(CharSequence s, int start,int count, int after){} 

               public void onTextChanged(CharSequence s, int start,int before, int count) 
               {
                    if(s.length() > 9)
                      {
                         //Do your stuff .
                         // You may show the intimation to user like don't try with more than 9 digits
                      }
                      else
                      {
                          //Do your stuff
                      }
               }

          });

这可能对你有所帮助。

Answer 2

@Fay Zan

基本上，您不希望用户为您的字段输入超过9位数字，这可以通过编程方式或使用布局视图属性

两种方式实现

在你的xml中，将此属性赋予EditText

android:maxLength="9"

通过检查字段的长度以编程方式进行OR。例如，假设您的字段的ID为@id+/portNo

然后像这样进行验证

private EditText mportNo;

在onCreate()

中

mportNo = (EditText) findViewById(R.id.portNo);
String portValue = mportNo.getText().toString();

if(portValue.length() > 9) {
    // throw error
}

如果数字超过9，则崩溃

2 个答案: