Java 编辑文本框中没有文本时，如何使按钮不可点击？

我知道如何使它不可点击“button.setEnabled（false）；”但不知道如何调用该函数。我尝试了if（editText.setText（））。感谢您的帮助。

editText.setText（）是一个void方法，您希望得到一个返回内容的方法（gettext）

您可以使用方法将

TextWatcher

添加到您的

EditText

中，并实现所有必要的逻辑以在或方法处启用\禁用按钮

---

只有一行解决方案。

我认为正确的方法是在

edittext

中添加一个点击式侦听器，然后从那里监视

onTextChanged

，如果字符串长度为0，则禁用按钮。应该是这样的：

    myButton = (Button) findViewById(R.id.button);
    myButton.setEnabled(false);
    EditText textMessage = (EditText)findViewById(R.id.editText);
    textMessage.addTextChangedListener(new TextWatcher() {
        @Override
        public void afterTextChanged(Editable s) {}

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

        @Override
        public void onTextChanged(CharSequence s, int start,int before, int count) {
            if(s.length() == 0)
                myButton.setEnabled(false);
            else
                myButton.setEnabled(true);
        }
    });

getText（）不返回返回的字符串它返回的是可编辑的，添加一个toString（）

  yourButton.setEnabled(!yourTextView.getText().toString.isEmpty());

    myButton = (Button) findViewById(R.id.button);
    myButton.setEnabled(false);
    EditText textMessage = (EditText)findViewById(R.id.editText);
    textMessage.addTextChangedListener(new TextWatcher() {
        @Override
        public void afterTextChanged(Editable s) {}

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

        @Override
        public void onTextChanged(CharSequence s, int start,int before, int count) {
            if(s.length() == 0)
                myButton.setEnabled(false);
            else
                myButton.setEnabled(true);
        }
    });

you can achive this in two way 

before using any aproach you write the code to disable the button in the 

oncreate() you set the button clickable false by default.
 //1.by using focus change listener
 //2.by using  TextchangeListener or TextWatcher the threshold to check the condition after the specific length of text

public class MainActivity extends Activity {
     private EditText editText;Button button;
    @Override
        public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    editText= (EditText) findViewById(R.id.editText1);


button= (Button) findViewById(R.id.button1);
            button.setEnabled(false);


    //1.by using focus change listener
     editText.setOnFocusChangeListener(new OnFocusChangeListener(){
    @Override
        public void onFocusChange(View v, boolean hasFocus) {
            if(editText.getText().toString().trim().length()>0)
            {    button.setEnabled(true); }
            else{  button.setEnabled(false);}
        }});

    //or
    //2.by using  TextchangeListener or TextWatcher
     editText.addTextChangedListener(new new TextWatcher(){
     @Override
    public void afterTextChanged(Editable s) {

           if(editText.getText().toString().trim().length()>0)
            {   
              button.setEnabled(true);
             } else{  button.setEnabled(false);}



 /*this function will call on every text entry so use
  some threshold so it  will be call once and validate 
    that threshold in if() as condition to make button clickable. */   
    }
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) { }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) { } });

    }
}

my suggestion is if you want to keep track of the letter than go for the addTextChangedListener 
else use the focusChangeListener code only