问题描述
- android 获取menu控件空指针异常
-
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!!!
解决方案
setSupportActionBar(toolbar);
//onPrepareOptionsMenu(menu); 注释掉这句话,这没必要调用
解决方案二:
注意看这行代码:
setSupportActionBar(toolbar);
这行代码是自动回调的,不需要你显式去调用,注释掉即可,类似这样的还有很多,以后可能还会有onKeyDown 等函数
时间: 2024-07-29 09:08:25