java - 如果不使用.equals方法，如何得到此错误？

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String signInMethod;
...

...
if (signInMethod != null) {
    if (signInMethod.equals("google")) {
        intent.putExtra("signInMethod", "google");
    } else if (signInMethod.equals("email")) {
        intent.putExtra("signInMethod", "email");
    }
} else {
    intent.putExtra("signInMethod", "alreadySignedIn");
}

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference

如果不使用.equals方法，如何得到此错误？

最佳答案

用这个。

  String signInMethod = null;
    if(TextUtils.isEmpty(signInMethod)){
        Toast.makeText(context, "Some thing wrong please try again", Toast.LENGTH_SHORT).show();
    }else {
        if (signInMethod.equalsIgnoreCase("google")) {
            intent.putExtra("signInMethod", "google");
        } else if (signInMethod.equalsIgnoreCase("email")) {
            intent.putExtra("signInMethod", "email");
        } else {
            intent.putExtra("signInMethod", "alreadySignedIn");
        }
    }