Question

    public class ActivityMain extends AppCompatActivity {
    Button button;
    TextView tv;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button=findViewById(R.id.button_chatbox_send);
        button.setEnabled(false);
        tv= findViewById(R.id.edittext_chatbox);
        tv.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int start, int before, int count) {
                if (charSequence.toString().equals("")) {
                    button.setEnabled(false);
                } else {
                    button.setEnabled(true);
                }

            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        });

button.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view)
            {
//Call other method with string from text view as parameter
            }
            }
        });

}

我在TextView中添加了TextChangedListener以禁用Button，而文本视图不包含字符串。在运行时，在我将字符串输入TextView后，即使我删除了所有文本，按钮仍然处于启用状态。如何解决这个问题，我在点击时使用的方法不能用空字符串？

修改

问题解决了。

Answer 1

在onTextChanged或textChanged

之后更新您的按钮

tv.addTextChangedListener(new TextWatcher() {

        @Override
        public void afterTextChanged(Editable s) {
            button.setEnabled(!TextUtils.isEmpty(s.toString()));  // Update button here OR 

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

        }

        @Override
        public void onTextChanged(CharSequence s, int start,
                                  int before, int count) {
            button.setEnabled(count>0); // Update button here
        }
    });

Answer 2

将其移至afterTextChanged

 @Override
    public void afterTextChanged(Editable editable) {
        button.setEnabled(!TextUtils.isEmpty(editable.toString()));
    }

Answer 3

您应该在onTextChanged -

的TextWatcher方法中停用该按钮

@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
    button.setEnabled(charSequence.toString().length() > 0);
}

删除textview内容后禁用按钮

3 个答案: