引起：java.lang.NullPointerException: Attempt to invoke interface method on a null object reference
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StackOverFlow
Caused by: java.lang.NullPointerException: Attempt to invoke interface method on a null object reference
提问by l7ivine
I am having trouble submitting the highscores to android leaderboards. Right now the leaderboards are empty and nothing is being submitted. I have an int "oldScore" that needs to be submitted. Right now I am trying a piece of code to submit it but the activity crashes when called. My code:
我无法将高分提交给 android 排行榜。现在排行榜是空的，没有提交任何内容。我有一个需要提交的 int“oldScore”。现在我正在尝试一段代码来提交它，但活动在调用时崩溃。我的代码：
public class GameOver extends BaseGameActivity implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {
private GoogleApiClient mGoogleApiClient;
public static int score;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_over);
mGoogleApiClient.connect();
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addApi(Drive.API)
.addScope(Drive.SCOPE_FILE)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
int newScore = GameOver.score;
SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
int oldScore = prefs.getInt("key", 0);
if (newScore > oldScore) {
SharedPreferences.Editor edit = prefs.edit();
edit.putInt("key", newScore);
edit.commit();
EditText HighScore = (EditText) findViewById(R.id.HighScoreT);
HighScore.setText("" + newScore);
} else {
EditText HighScore = (EditText) findViewById(R.id.HighScoreT);
HighScore.setText("" + oldScore);
Games.Leaderboards.submitScoreImmediate(getApiClient(),String.valueOf(R.string.number_guesses_leaderboard), oldScore);
}
}
Logcat:
日志猫：
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'void com.google.android.gms.common.api.GoogleApiClient.connect()' on a null object reference
引起：java.lang.NullPointerException：尝试在空对象引用上调用接口方法“void com.google.android.gms.common.api.GoogleApiClient.connect()”
回答by Reimeus
The statement
该声明
mGoogleApiClient.connect();
should appear after mGoogleApiClienthas been instantiated
应该在mGoogleApiClient实例化后出现
回答by Sanjeet A
You are invoking the method
您正在调用该方法
connect()
on the object
在物体上
mGoogleApiClient
without instantiating it
没有实例化它
You need to write this first,
你需要先写这个，
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addApi(Drive.API)
.addScope(Drive.SCOPE_FILE)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
then this,
那么这个，
mGoogleApiClient.connect();
回答by Elliott Frisch
You can't call connect()until afteryou initialize the mGoogleApiClientreference. Like,
你不能打电话connect()，直到后您初始化mGoogleApiClient参考。喜欢，
// mGoogleApiClient.connect();
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addApi(Drive.API)
.addScope(Drive.SCOPE_FILE)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
mGoogleApiClient.connect(); // <-- move to here.
回答by Santhosh
Try this process : Assign google client before loading contentview:
试试这个过程：在加载内容视图之前分配谷歌客户端：
private GoogleApiClient mGoogleApiClient;
public static int score;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addApi(Drive.API)
.addScope(Drive.SCOPE_FILE)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
setContentView(R.layout.activity_game_over);
}
Add override onStart and connect the google client.
添加覆盖 onStart 并连接谷歌客户端。
@Override
public void onStart() {
super.onStart();
mGoogleApiClient.connect();
}
@Override
public void onStop() {
super.onStop();
mGoogleApiClient.disconnect();
}
