这是我的代码：
public class MainActivity extends AppCompatActivity
{
private static Toolbar action_add;
private static Menu menu;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
onPrepareOptionsMenu(menu);
action_add.setOnClickListener(new Toolbar.OnClickListener()
{
public void onClick(View v)
{
showDialog_Layout(MainActivity.this);
}
});
}
@Override
public boolean onPrepareOptionsMenu(Menu menu)
{
super.onPrepareOptionsMenu(menu);
menu.findItem(R.id.action_add).setChecked(true);
return true;
}
private void showDialog_Layout(Context context) {
LayoutInflater inflater = LayoutInflater.from(this);
final View textEntryView = inflater.inflate(R.layout.dialoglayout, null);
final EditText edtInput=(EditText)textEntryView.findViewById(R.id.edtInput);
final AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setCancelable(false);
builder.setIcon(R.drawable.a);
builder.setTitle("Title");
builder.setView(textEntryView);
builder.setPositiveButton("确认",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
setTitle(edtInput.getText());
}
});
builder.setNegativeButton("取消",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
setTitle("");
}
});
builder.show();
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return super.onCreateOptionsMenu(menu);
}
}
这是我的错误：
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'android.view.MenuItem android.view.Menu.findItem(int)' on a null object reference
在
onPrepareOptionsMenu(menu);
menu.findItem(R.id.action_add).setChecked(true);
两行，大神给看看呗！！！
