i’m just programming a password manager but every time I run it, it crashed in cause of NullPointerException. I checked the code but i’m a new developer. Someone here who knows why? 🙁
Code of MainActivity.java:
package de.lennartschoch.passwordmanager;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends Activity {
Button login;
EditText masterpassfield;
static String masterpass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
login = (Button) findViewById(R.id.login);
masterpass = "";
masterpassfield = (EditText) findViewById(R.id.masterpass);
if(masterpass.equals("")) {
Intent intent = new Intent(this,NewMasterpass.class);
startActivity(intent);
return;
}
login.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
if(masterpassfield.getText().toString().equals(masterpass)) {
Intent success = new Intent(view.getContext(), Passwords.class);
startActivityForResult(success, 0);
}
}});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
Code of NewMasterpass.java:
package de.lennartschoch.passwordmanager;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class NewMasterpass extends Activity {
EditText masterpasscreate;
EditText repeat;
Button finish;
TextView mistake;
/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_masterpass);
masterpasscreate = (EditText) findViewById(R.id.masterpasscreate);
repeat = (EditText) findViewById(R.id.repeatcreate);
finish = (Button) findViewById(R.id.finish);
mistake = (TextView) findViewById(R.id.mistake);
finish.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
if(!masterpasscreate.getText().toString().equals(repeat.getText().toString())) {
mistake.setText("The passwords are different.");
mistake.setTextColor(Color.RED);
}
else if(masterpasscreate.getText().toString().equals("") || repeat.getText().toString().equals("")) {
mistake.setText("Both textfields must be filled in");
mistake.setTextColor(Color.RED);
}
else {
MainActivity.masterpass = masterpasscreate.getText().toString();
Intent myIntent = new Intent(view.getContext(), MainActivity.class);
startActivityForResult(myIntent, 0);
}
}});
}
}
LogCat error:
01-20 17:17:52.629: D/AndroidRuntime(561): Shutting down VM
01-20 17:17:52.629: W/dalvikvm(561): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
01-20 17:17:52.639: E/AndroidRuntime(561): FATAL EXCEPTION: main
01-20 17:17:52.639: E/AndroidRuntime(561): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.lennartschoch.passwordmanager/de.lennartschoch.passwordmanager.MainActivit y}: java.lang.NullPointerException
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.ActivityThread.access$600(ActivityThread.java:122)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.os.Handler.dispatchMessage(Handler.java:99)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.os.Looper.loop(Looper.java:137)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.ActivityThread.main(ActivityThread.java:4340)
01-20 17:17:52.639: E/AndroidRuntime(561): at java.lang.reflect.Method.invokeNative(Native Method)
01-20 17:17:52.639: E/AndroidRuntime(561): at java.lang.reflect.Method.invoke(Method.java:511)
01-20 17:17:52.639: E/AndroidRuntime(561): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-20 17:17:52.639: E/AndroidRuntime(561): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-20 17:17:52.639: E/AndroidRuntime(561): at dalvik.system.NativeStart.main(Native Method)
01-20 17:17:52.639: E/AndroidRuntime(561): Caused by: java.lang.NullPointerException
01-20 17:17:52.639: E/AndroidRuntime(561): at de.lennartschoch.passwordmanager.MainActivity.onCreate(MainActivity.java:26)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.Activity.performCreate(Activity.java:4465)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
01-20 17:17:52.639: E/AndroidRuntime(561): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
01-20 17:17:52.639: E/AndroidRuntime(561): ... 11 more
01-20 17:17:57.129: I/Process(561): Sending signal. PID: 561 SIG: 9
01-20 17:21:37.499: D/AndroidRuntime(608): Shutting down VM
01-20 17:21:37.499: W/dalvikvm(608): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
01-20 17:21:37.511: E/AndroidRuntime(608): FATAL EXCEPTION: main
01-20 17:21:37.511: E/AndroidRuntime(608): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.lennartschoch.passwordmanager/de.lennartschoch.passwordmanager.MainActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {de.lennartschoch.passwordmanager/de.lennartschoch.passwordmanager.NewMasterpass}; have you declared this activity in your AndroidManifest.xml?
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.ActivityThread.access$600(ActivityThread.java:122)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.os.Handler.dispatchMessage(Handler.java:99)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.os.Looper.loop(Looper.java:137)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.ActivityThread.main(ActivityThread.java:4340)
01-20 17:21:37.511: E/AndroidRuntime(608): at java.lang.reflect.Method.invokeNative(Native Method)
01-20 17:21:37.511: E/AndroidRuntime(608): at java.lang.reflect.Method.invoke(Method.java:511)
01-20 17:21:37.511: E/AndroidRuntime(608): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-20 17:21:37.511: E/AndroidRuntime(608): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-20 17:21:37.511: E/AndroidRuntime(608): at dalvik.system.NativeStart.main(Native Method)
01-20 17:21:37.511: E/AndroidRuntime(608): Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {de.lennartschoch.passwordmanager/de.lennartschoch.passwordmanager.NewMasterpass}; have you declared this activity in your AndroidManifest.xml?
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1508)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1384)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.Activity.startActivityForResult(Activity.java:3190)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.Activity.startActivity(Activity.java:3297)
01-20 17:21:37.511: E/AndroidRuntime(608): at de.lennartschoch.passwordmanager.MainActivity.onCreate(MainActivity.java:30)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.Activity.performCreate(Activity.java:4465)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
01-20 17:21:37.511: E/AndroidRuntime(608): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
01-20 17:21:37.511: E/AndroidRuntime(608): ... 11 more
01-20 17:22:30.769: D/AndroidRuntime(655): Shutting down VM
01-20 17:22:30.769: W/dalvikvm(655): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
01-20 17:22:30.779: E/AndroidRuntime(655): FATAL EXCEPTION: main
01-20 17:22:30.779: E/AndroidRuntime(655): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.lennartschoch.passwordmanager/de.lennartschoch.passwordmanager.MainActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {de.lennartschoch.passwordmanager/de.lennartschoch.passwordmanager.NewMasterpass}; have you declared this activity in your AndroidManifest.xml?
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.ActivityThread.access$600(ActivityThread.java:122)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.os.Handler.dispatchMessage(Handler.java:99)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.os.Looper.loop(Looper.java:137)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.ActivityThread.main(ActivityThread.java:4340)
01-20 17:22:30.779: E/AndroidRuntime(655): at java.lang.reflect.Method.invokeNative(Native Method)
01-20 17:22:30.779: E/AndroidRuntime(655): at java.lang.reflect.Method.invoke(Method.java:511)
01-20 17:22:30.779: E/AndroidRuntime(655): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-20 17:22:30.779: E/AndroidRuntime(655): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-20 17:22:30.779: E/AndroidRuntime(655): at dalvik.system.NativeStart.main(Native Method)
01-20 17:22:30.779: E/AndroidRuntime(655): Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {de.lennartschoch.passwordmanager/de.lennartschoch.passwordmanager.NewMasterpass}; have you declared this activity in your AndroidManifest.xml?
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1508)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1384)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.Activity.startActivityForResult(Activity.java:3190)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.Activity.startActivity(Activity.java:3297)
01-20 17:22:30.779: E/AndroidRuntime(655): at de.lennartschoch.passwordmanager.MainActivity.onCreate(MainActivity.java:30)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.Activity.performCreate(Activity.java:4465)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
01-20 17:22:30.779: E/AndroidRuntime(655): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
01-20 17:22:30.779: E/AndroidRuntime(655): ... 11 more
01-20 17:22:33.180: I/Process(655): Sending signal. PID: 655 SIG: 9
Declare the
NewMasterPassactivity in your manifest xml as clearly mentioned in the logcat!