Android：NullPointerException：尝试调用虚拟方法'boolean

Question

我得到以下错误：

*E/AndroidRuntime: FATAL EXCEPTION: main
Process: xxx.mxxxa.xxx, PID: 10610
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean    java.lang.String.contains(java.lang.CharSequence)' on a null object reference* 

在以下线路上：

public void onLoadResource (WebView view, String url) {
if (datingView.getUrl().contains("messages.php") && datingView.getUrl().contains("messages.php" +
"")){
bannerReklam.setVisibility(View.GONE);
}else if (datingView.getUrl().contains("upgrade.php") && datingView.getUrl().contains("upgrade.php" +
"")){
bannerReklam.setVisibility(View.GONE);
}else if (datingView.getUrl().contains("index.php") && datingView.getUrl().contains("index.php" +
"")){
bannerReklam.setVisibility(View.GONE);
}else if (datingView.getUrl().contains("join.php") && datingView.getUrl().contains("join.php" +
"") ){
bannerReklam.setVisibility(View.GONE);
}else{
bannerReklam.setVisibility(View.VISIBLE);
}
// if url contains string androidexample
// Then show progress  Dialog
if (progressDialog == null && url.contains("instasquare")
) {
// in standard case YourActivity.this
progressDialog = new ProgressDialog(arkadasBulMain.this);
progressDialog.setMessage("Loading...");
progressDialog.show();
}
}

此问题导致应用程序停止。此错误发生在android 9.0以下的版本。

Answer 1

在某些情况下，datingView.getUrl()返回null。首先尝试检查null，然后尝试使用contains搜索项目。例如：

String datingUrl = datingView.getUrl();
if(datingUrl != null && datingUrl.contains("messages.php"))