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我正在嘗試在導航抽屜中使用seekbar。我的錯誤是什麼?在沒有導航抽屜的應用程序中沒有問題。謝謝。SeekBar on Navigation抽屜
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
TextView textView;
SeekBar seekBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
seekBar = (SeekBar) findViewById(R.id.seekbar);
textView = (TextView) findViewById(R.id.txtView);
seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
textView.setText(String.valueOf(progress));
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.SeekBar.setOnSeekBarChangeListener(android.widget.SeekBar$OnSeekBarChangeListener)' on a null object reference
? – Aznhar
seekBar爲null添加布局xml –
我創建了seekbar.xml並添加了activity_main_drawer.xml - app:actionLayout =「@ layout/seekbar」 –