“看看这个，我相信你会喜欢的。”

log_in.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        username=user_name.getText().toString();
        password=pass_word.getText().toString();
        if(username.equals(""))
        {
            user_name.setError("Enter username");
        }
        else if(password.equals(""))
        {
            pass_word.setError("Enter your password");
        }
        else
        {
            Intent intent=new Intent(MainActivity.this,Scan_QRActivity.class);
            startActivity(intent);
        }
    }
});

我使用这个方法，使用trim()来避免空格:

EditText myEditText = (EditText) findViewById(R.id.editUsername);
if ("".equals(myEditText.getText().toString().trim()) {
    Toast.makeText(this, "You did not enter a value!", Toast.LENGTH_LONG).show();
    return;
}

一个例子，如果你有几个EditText´

if (("".equals(edtUser.getText().toString().trim()) || "".equals(edtPassword.getText().toString().trim()))){
        Toast.makeText(this, "a value is missing!", Toast.LENGTH_LONG).show();
        return;
}

试试这个吧: 它在Kotlin

//button from xml
button.setOnClickListener{                                         
    val new=addText.text.toString()//addText is an EditText
    if(new=isNotEmpty())
    {
         //do something
    }
    else{
        new.setError("Enter some msg")
        //or
        Toast.makeText(applicationContext, "Enter some message ", Toast.LENGTH_SHORT).show()
    }
}

谢谢你！

我曾经做过类似的事情;

EditText usernameEditText = (EditText) findViewById(R.id.editUsername);
sUsername = usernameEditText.getText().toString();
if (sUsername.matches("")) {
    Toast.makeText(this, "You did not enter a username", Toast.LENGTH_SHORT).show();
    return;
}

我想做一些类似的事情。但是从edit text中获取文本值并像(str=="")那样进行比较对我来说并不管用。所以更好的选择是:

EditText eText = (EditText) findViewById(R.id.etext);

if (etext.getText().length() == 0)
{//do what you want }

效果很好。

if ( (usernameEditText.getText()+"").equals("") ) { 
    // Really just another way
}