Question

我按照http://developer.android.com/training/location/retrieve-current.html中提供的说明显示用户位置。但导致上述编译错误。

这是我的代码

public class MainActivity extends ActionBarActivity implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {

    private GoogleApiClient mGoogleApiClient;
    private Location mLastLocation;
    TextView tv1 = (TextView) findViewById(R.id.lat);
    TextView tv2 = (TextView) findViewById(R.id.lon);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); //ERROR '}' expected

        protected synchronized void buildGoogleApiClient() {
            mGoogleApiClient = new GoogleApiClient.Builder(this)
                    .addConnectionCallbacks(this)
                    .addOnConnectionFailedListener(this)
                    .addApi(LocationServices.API)
                    .build();
        }
    } // ERROR 'class' or 'interface' expected


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onConnected(Bundle connectionHint) {
        mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
                mGoogleApiClient);
        if (mLastLocation != null) {
            tv1.setText(String.valueOf(mLastLocation.getLatitude()));
            tv1.setText(String.valueOf(mLastLocation.getLongitude()));
        }
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }
}

我经历了错误并发现了语法错误。任何人都可以告诉我为什么它在编译中失败了吗？

Answer 1

您的buildGoogleApiClient方法无法进入onCreate方法。

将其更改为：

protected synchronized void buildGoogleApiClient() {
    mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    buildGoogleApiClient ();
}

或者：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
}

Answer 2

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main); //ERROR '}' expected

    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }
} // ERROR 'class' or 'interface' expected

应该是：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main); } // curly brace to close method and clean up error

    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }
// removing this curly brace should clear up the error here

由于错位的花括号，您的语法已关闭。留意小事。

Answer 3

您的代码存在的问题是您正在尝试在另一个函数（onCreate）中定义一个函数（buildGoogleApiClient），这是Java无法实现的。

protected void onCreate(Bundle savedInstanceState) { 
    //
    // Body of this function
    //
}

所以基本上在Java花括号中标记代码块的边界。代码块可以是if-block，while-block或function-block等.Java不允许功能块内的功能块。只有class-block可以包含一个功能块。

因此，您需要直接在class-block下定义函数。

public class Blah extends Activity implements BlahInterface {

    private BlahApiClient mBlahApiClient;

    protected synchronized void buildBlahApiClient() {
        mBlahApiClient = new BlahApiClient.Builder(this)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .addApi(LocationServices.API)
            .build();
    }

    protected void onCreate( Bundel savedInstanceState ) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // You can call (execute) any defined function inside this function
        buildBlahApiClient();

   }

}

预计Android Studio“类”或“界面”

3 个答案: