How to force to do when button clicked from other activity

I want to toDo() work App.class (AllActivity) when button clicked from other example.class.(Activity)

public class Otherclass extend AppCompatActivity{

Button example = (Button)findViewById(R.id.option_language);
example.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
example.isChecked();
}
});
}

public class App extends Application {
@Override
public void onCreate() {
super.onCreate();
ToDo();
}


@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
toDo();
}

public void toDo() {
if(new OtherClass().example.isChecked()) {
// To do something.
}
}
}
}


I wanted to do it. But, I got java.lang.NullPointerException: .isChecked()' on a null object reference

3 Answers
3

This is a bad behavior that you implemented.

If you want to check whether the example button is clicked or not. Simply take a boolean flag in Your App class, and set it's value on the button click.

App

And if you wish to pass this flag from one activity to another simply use intent for it.

public class Otherclass extend AppCompatActivity{

Button example = (Button)findViewById(R.id.option_language);
example.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
App.setIsChecked(true);
}
});
}

public class App extends Application {
public static boolean isChecked = false;
@Override
public void onCreate() {
super.onCreate();
ToDo();
}

public void setIsChecked(boolean isChecked) {
this.isChecked = isChecked;
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
toDo();
}

public void toDo() {
if(isChecked) {
// To do something.
}
}
}
}


getIntent()

you can call todo method of App class on any button click like this

((App)getApplication()).todo();


public class Otherclass extend AppCompatActivity{
static Boolean checked=false;
Button example = (Button)findViewById(R.id.option_language);
example.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
checked=true;
}
});
}

public class App extends Application {
@Override
public void onCreate() {
super.onCreate();
ToDo();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
toDo();
}

public void toDo() {
if(new OtherClass().checked) {
// To do something.
}
}
}

}


Might this will be useful
This is bad coding practice to use static in class. Instead, use intents to communicate between class

Boolean checked=false;

App

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