标签:android java nullpointerexception
参见英文答案 > What is a NullPointerException, and how do I fix it? 12个
我在运行时收到此错误.
java.lang.RuntimeException: Unable to start activity ComponentInfo
java.lang.NullPointerException: Attempt to invoke virtual method
‘boolean java.lang.String.equalsIgnoreCase(java.lang.String)’ on a
null object reference
堆栈跟踪:
01-12 03:44:54.270: E/AndroidRuntime(1437): FATAL EXCEPTION: main
01-12 03:44:54.270: E/AndroidRuntime(1437): Process: home.saket, PID: 1437
01-12 03:44:54.270: E/AndroidRuntime(1437): java.lang.RuntimeException: Unable to start activity ComponentInfo{home.saket/home.saket.addmember.Add_Update_User}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equalsIgnoreCase(java.lang.String)' on a null object reference
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.ActivityThread.access$800(ActivityThread.java:144)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.os.Handler.dispatchMessage(Handler.java:102)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.os.Looper.loop(Looper.java:135)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.ActivityThread.main(ActivityThread.java:5221)
01-12 03:44:54.270: E/AndroidRuntime(1437): at java.lang.reflect.Method.invoke(Native Method)
01-12 03:44:54.270: E/AndroidRuntime(1437): at java.lang.reflect.Method.invoke(Method.java:372)
01-12 03:44:54.270: E/AndroidRuntime(1437): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
01-12 03:44:54.270: E/AndroidRuntime(1437): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
01-12 03:44:54.270: E/AndroidRuntime(1437): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equalsIgnoreCase(java.lang.String)' on a null object reference
01-12 03:44:54.270: E/AndroidRuntime(1437): at home.saket.addmember.Add_Update_User.onCreate(Add_Update_User.java:38)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.Activity.performCreate(Activity.java:5933)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
01-12 03:44:54.270: E/AndroidRuntime(1437): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
01-12 03:44:54.270: E/AndroidRuntime(1437): ... 10 more
01-12 03:44:54.272: W/ActivityManager(472): Force finishing activity home.saket/.addmember.Add_Update_User
01-12 03:44:54.273: E/ActivityManager(472): Invalid thumbnail dimensions: 384x384
下面我发布了代码并指出了错误行.
Add_Update_User.java:
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.add_update_screen);
// set screen
Set_Add_Update_Screen();
// set visibility of view as per calling activity
String called_from = getIntent().getStringExtra("called");
if (called_from.equalsIgnoreCase("add")) { --->38th error line
add_view.setVisibility(View.VISIBLE);
update_view.setVisibility(View.GONE);
} else {
update_view.setVisibility(View.VISIBLE);
add_view.setVisibility(View.GONE);
USER_ID = Integer.parseInt(getIntent().getStringExtra("USER_ID"));
Contact c = dbHandler.Get_Contact(USER_ID);
add_name.setText(c.getName());
add_mobile.setText(c.getPhoneNumber());
add_email.setText(c.getEmail());
// dbHandler.close();
}
}
解决方法:
called_from必须为null.添加针对该条件的测试,如
if (called_from != null && called_from.equalsIgnoreCase("add")) {
或者您可以使用Yoda conditions(根据链接的维基百科文章中的优点,它也可以解决某些类型的不安全的空行为,它们可以被描述为将表达式的常量部分放在条件语句的左侧)
if ("add".equalsIgnoreCase(called_from)) { // <-- safe if called_from is null
标签:android,java,nullpointerexception 来源: https://codeday.me/bug/20191005/1856382.html
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