Question

我有这个应用程序，它在列表视图中输出我在状态文本字段中输入的内容。但是，我需要添加一个函数，如果状态文本字段为空，则POST按钮不应该被禁用。我实际上读到了包含文本观察者的内容，但我不确定如何整合它。

    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.support.v7.widget.FitWindowsFrameLayout;
    import android.view.View;
    import android.widget.ArrayAdapter;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.ListView;

    import java.util.ArrayList;
    import java.util.List;

    public class MainActivity extends AppCompatActivity {
        private ArrayList<FriendStatusMessage> mMessageList = new ArrayList<FriendStatusMessage>();
        ArrayAdapter<FriendStatusMessage> mAdapter = null;

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

            Button btnPost = (Button) findViewById(R.id.btn_post);
            btnPost.setOnClickListener(
                    new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            postMessage();
                            return;
                        }
                    }
            );


            mAdapter = new ArrayAdapter<FriendStatusMessage>(this, android.R.layout.simple_list_item_1, mMessageList);
            ListView lstMessages = (ListView) findViewById(R.id.lst_messages);
            lstMessages.setAdapter(mAdapter);
        }

        private void postMessage() {
            EditText edtUsername = (EditText) findViewById(R.id.edt_username);
            EditText edtStatusMessage = (EditText) findViewById(R.id.edt_status_msg);

            String userStr = edtUsername.getText().toString();
            String messageStr = edtStatusMessage.getText().toString();

            mMessageList.add(new FriendStatusMessage(userStr, messageStr));
            mAdapter.notifyDataSetChanged();
            return;

        }

        private class FriendStatusMessage {
            private String mUsername = "";
            private String mMessage = "";

            public FriendStatusMessage(String username, String statusMessage) {
                mUsername = username;
                mMessage = statusMessage;
            }

            public String getmUsername()
            {
                return mUsername;
            }

            public String getmMessage ()
            {
                return  mMessage;
            }

            public String toString() {
                return getmUsername() + ": " + getmMessage() + "\n";
            }
        }
    }

Answer 1

如果不采取行动呢？

    private void postMessage() {
        EditText edtUsername = (EditText) findViewById(R.id.edt_username);
        EditText edtStatusMessage = (EditText) findViewById(R.id.edt_status_msg);

        String userStr = edtUsername.getText().toString();
        String messageStr = edtStatusMessage.getText().toString();

        boolean doAction = false;
        if (userStr.isEmpty()) {
            edtUsername.setError("Must enter username");
        }
        if (messageStr.isEmpty()) {
            edtStatusMessage.setError("Must enter status");
        }
        doAction = true;

        if (doAction) {
            mMessageList.add(new FriendStatusMessage(userStr, messageStr));
            mAdapter.notifyDataSetChanged();
        }
    }

否则，您需要将这些内容移至onCreate

EditText edtUsername = (EditText) findViewById(R.id.edt_username);
EditText edtStatusMessage = (EditText) findViewById(R.id.edt_status_msg);

正确addTextChangedListener到那些。

Answer 2

试试这个，这是一个更好的选择

       void postMessage() {
                EditText edtUsername = (EditText) findViewById(R.id.edt_username);
                edtUsername.setError(null);
                EditText edtStatusMessage = (EditText) findViewById(R.id.edt_status_msg);
                edtStatusMessage.setError(null);

                String userStr = edtUsername.getText().toString();
                String messageStr = edtStatusMessage.getText().toString();

                if (TextUtils.isEmpty(userStr)) {
                        edtUsername.setError("This shouldn't be blank");
                        edtUsername.requestFocus();
                }else (TextUtils.isEmpty(messageStr)) {
                        edtStatusMessage.setError("This shouldn't be blank");
                        edtStatusMessage.requestFocus();
                }else{
                        mMessageList.add(new FriendStatusMessage(userStr, messageStr));
                        mAdapter.notifyDataSetChanged();
                }
       }

Answer 3

您需要输入文字验证和＆amp; addTextChangedListener用于发布按钮操作。空文本验证后，您可以启用发布按钮来执行后期操作。您还可以在edtStatusMessage上使用TextWatcher来执行后期操作。

    private  EditText edtUsername, edtStatusMessage ;
    private  Button btnPost;

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

            edtUsername = (EditText) findViewById(R.id.edt_username);

            edtStatusMessage = (EditText) findViewById(R.id.edt_status_msg);

            btnPost = (Button) findViewById(R.id.btn_post);

           btnPost.setEnabled(false); 
           edtStatusMessage.addTextChangedListener(listenerTextChangedStatus );

        }    


    private TextWatcher listenerTextChangedStatus = new TextWatcher() {
            public void afterTextChanged(Editable editable) {      


          }

      @Override
      public void beforeTextChanged(CharSequence s, int start, int count,
            int after) {


      }

      @Override
      public void afterTextChanged(Editable s) {

         if(!edtUsername.getText().toString().isEmpty() && !s.getText().toString().isEmpty()){
            btnPost.setEnabled(true); 
           // do action
                btnPost.setOnClickListener(
                    new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            postMessage();
                            return;
                        }
                    }
              );

        }else{
             btnPost.setEnabled(false); 
             edtStatusMessage.setFocus(true);
          }

      }

};

for more information follow the link
http://stackoverflow.com/questions/8543449/how-to-use-the-textwatcher-class-in-android

输入为空时禁用后置按钮（Android）

3 个答案: