Question

i’am beginner and i’am trying to make a simple calculator for android but he give me a syntax error

public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    final EditText e  = (EditText)findViewById(R.id.value);
    final EditText e2 = (EditText)findViewById(R.id.value2);

    getMenuInflater().inflate(R.menu.activity_main, menu);
    Toast.makeText(this,"Welcome",Toast.LENGTH_LONG).show();
    Button welcome = (Button)findViewById(R.id.x);
    welcome.setText("push ");
    welcome.setonclickListener(new View.onclickListener() {

        @Override
        public void onclick(View v) {
            int v1 = Integer.parseInt(e.getText().toString());
            int v2 = Integer.parseInt(e2.getText().toString());
            int v3 = v1 + v2 ;
            Toast.makeText(MainActivity.this,"= " + v3, Toast.LENGTH_LONG).show();

             return true;

         }
         });

}

}

http://imageshack.us/photo/my-images/24/problem00.png/

Answer 1

Use OnClickListener(). You don’t have to specify View. Also, make sure you use a capital ‘C’ in the overridden onClick() method. Make sure you include import android.view.View.OnClickListener; in your imports section. Eclipse should this for you, but if it’s not or you are using Eclipse, add it manually to the top of the class. If you simply do the following, that should work for you:

     welcome.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            int v1 = Integer.parseInt(e.getText().toString());
            int v2 = Integer.parseInt(e2.getText().toString());
            int v3 = v1 + v2;
            Toast.makeText(MainActivity.this, "= " + v3, Toast.LENGTH_LONG).show();

            return true;

        }
    });

——–EDITED FOR FULL EXAMPLE——–

In your project, you have your main activity. That activity should use a layout from an XML resource. That XML resource likely looks something like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" />
</LinearLayout>

In your activity class, you have to set that resource as the content view for the activity, using setContentView(resID). Say your XML file is called helloworld.xml, you would execute setContentView(R.layout.helloworld) in the activity’s onCreate(Bundle s) method right after calling super.onCreate(s).

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.helloworld);

}

Once you have set the activity’s view, you can access that layout’s elements (EditTexts, Buttons, etc). To do this, you’ll have to create EditText and Button objects (which you were already doing in your posted code, we just have to do them elsewhere instead). Continuing with my example, you could do the following in your onCreate(Bundle s) function:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.helloworld);

    EditText et1 = (EditText) findViewById(R.id.edittext1);
    EditText et2 = (EditText) findViewById(R.id.edittext2);
    Button but = (Button) findViewById(R.id.button1);

    but.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v)
            et2.setText(et1.getText().toString());
            // this will set the second EditText's text to whatever is in
            // the first EditText, but you could do anything with the value.
        }
    }
}

If you want to change what the button does based on a menu item selection, you have to override onOptionsItemSelected(MenuItem item) in addition to onCreateOptionsMenu(Menu menu). onCreateOptionsMenu(Menu menu) simply creates the menu for the menu button to open. onOptionsItemSelected(MenuItem item) actually decides what to do when you select a menu item.

See the tutorial at this page for full rundown http://developer.android.com/guide/topics/ui/menus.html, but here are their examples with some explanation. These examples are not from my example app above but from the Android Developer API pages. I strongly recommend you go over their tutorial.

All you have to do in onCreateOptionsMenu(Menu menu) is tell Android where to get the menu and to inflate that resource. This means there is an XML file called game_menu in the menu folder of the res folder in your project’s directory.

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.game_menu, menu);
    return true;
}

onOptionsItemSelected(MenuItem item) is where the meat of the menu logic goes, letting you perform different tasks based on which menu item get’s selected. In this example, the game_menu XML file mentioned in the above function has menu items called new_game and help.

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle item selection
    switch (item.getItemId()) {
        case R.id.new_game:
            newGame();
            return true;
        case R.id.help:
            showHelp();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}