Trouble with Intent in Android Studio

Question

I have been trying to get a string to go from one java class to another for a project of mine. The code I have been experimenting with is not working. When I press the button, I know it opens the other Java class because it creates the other layout, but it doesn't show the string. Please help me.

First Java Class:

public class MainActivity extends AppCompatActivity {

private Button button;
Context context;
private EditText editText;
String number = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    context = this;

    editText = (EditText) findViewById(R.id.editText);
    button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (editText.getText().toString() != null) {
                String value = "value";
                Intent secondscreenIntent = new Intent(context, SecondScreenJ.class);
                secondscreenIntent.putExtra("Number", editText.getText().toString());
                startActivity(secondscreenIntent);


            }
        }
    });
}
}

Second Java Class:

public class SecondScreenJ extends Activity {

String number = null;
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.secondscreen);

    textView = (TextView) findViewById(R.id.textView);

    Bundle extras = getIntent().getExtras();
    if (extras != null){
        number = extras.getString("number");
    }

    textView.setText(number);

}


}

Answer 1

you are putting "Number" as key but, in your second activity you are trying to retrieve "number" so change number to Number and it will work. Its case Sensitive.

Answer 2

Don't make your keys hard-coded in that way. Just declare public static variable in MainActivity and use it from SecondScreenJ

public class MainActivity extends AppCompatActivity {

private Button button;
Context context;
private EditText editText;
public static String NUMBER_KEY = "Number";
String number = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

context = this;

editText = (EditText) findViewById(R.id.editText);
button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if (editText.getText().toString() != null) {
            String value = "value";
            Intent secondscreenIntent = new Intent(context, SecondScreenJ.class);
            secondscreenIntent.putExtra(NUMBER_KEY , editText.getText().toString());
            startActivity(secondscreenIntent);


        }
    }
});
 }
 }

Second Java Class:

public class SecondScreenJ extends Activity {

String number = null;
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.secondscreen);

 textView = (TextView) findViewById(R.id.textView);

 Bundle extras = getIntent().getExtras();
 if (extras != null){
    number = extras.getString(MainActivity.NUMBER_KEY);
 }

 textView.setText(number);

 }


}

Answer 3

Beware when using the key for putting and getting the extras. They're case sensitive. Replace "number" with "Number" in your second activity.