第一步，先在布局中为EditText设置属性

android:singleLine="true"

android:imeOptions="actionDone"/>

第二步：在java代码中监听：

myCourse_roomId_input.setOnEditorActionListener(new TextView.OnEditorActionListener() {            @Override            public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {                //回车键                if(actionId == EditorInfo.IME_ACTION_DONE){                    Intent intent = new Intent(getActivity(), TopicInfoActivity.class);                    intent.putExtra(IntentKey.topicId, myCourse_roomId_input.getText().toString());                    startActivity(intent);                }                return true;            }        });

myCourse_roomId_input.addTextChangedListener(new TextWatcher() {            private CharSequence temp;            @Override            public void beforeTextChanged(CharSequence s, int start, int count, int after) {                temp = s;            }            @Override            public void onTextChanged(CharSequence s, int start, int before, int count) {            }            @Override            public void afterTextChanged(Editable s) {                if (temp.length() > 0) {
   //限制长度                    myCourse_roomId_clear.setVisibility(View.VISIBLE);                } else {                    myCourse_roomId_clear.setVisibility(View.GONE);                }            }        });