Question

[这是我的MainActivity.java文件] [1]

package com.example.socialmediaintegration;

import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

import com.bumptech.glide.Glide;
import com.bumptech.glide.request.RequestOptions;
import com.facebook.AccessToken;
import com.facebook.AccessTokenTracker;
import com.facebook.CallbackManager;
import com.facebook.FacebookCallback;
import com.facebook.FacebookException;
import com.facebook.GraphRequest;
import com.facebook.GraphResponse;
import com.facebook.login.LoginResult;
import com.facebook.login.widget.LoginButton;

import org.json.JSONException;
import org.json.JSONObject;

import java.util.Arrays;


import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import de.hdodenhof.circleimageview.CircleImageView;

公共类MainActivity扩展了AppCompatActivity {

private LoginButton loginButton;
private CircleImageView circleImageView;
private TextView txtName, txtEmail;

private CallbackManager callbackManager;

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

   // private static final String EMAIL = "email";

    loginButton =  findViewById(R.id.login_button);
    circleImageView = findViewById(R.id.profile_pic);
    txtName = findViewById(R.id.profile_name);
    txtEmail = findViewById(R.id.profile_email);

    callbackManager = CallbackManager.Factory.create();
    loginButton.setPermissions(Arrays.asList("email", "public_profile"));
    checkLoginStatus();


    loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
        @Override
        public void onSuccess(LoginResult loginResult) {

        }

        @Override
        public void onCancel() {

        }

        @Override
        public void onError(FacebookException error) {

        }
    });

}

@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    callbackManager.onActivityResult(requestCode, resultCode, data);
    super.onActivityResult(requestCode, resultCode, data);
}

AccessTokenTracker tokenTracker = new AccessTokenTracker() {
    @Override
    protected void onCurrentAccessTokenChanged(AccessToken oldAccessToken, AccessToken currentAccessToken) {

        if (currentAccessToken == null)
        {
            txtName.setText("");
            txtEmail.setText("");
            circleImageView.setImageResource(0);
            Toast.makeText(MainActivity.this, "User Logged out", Toast.LENGTH_LONG).show();
        }
        else {
            loadUserProfile(currentAccessToken);
        }
    }
};

private void loadUserProfile(AccessToken newAccessToken){
    GraphRequest request = GraphRequest.newMeRequest(newAccessToken, new GraphRequest.GraphJSONObjectCallback() {
        @Override
        public void onCompleted(JSONObject object, GraphResponse response) {
            try {
                String first_name = object.getString("first_name");
                String last_name = object.getString("last_name");
                String email = object.getString("email");
                String id = object.getString("id");

                String image_url =  "http://graph.facebook.com/"+id+"/picture?type=normal";

                txtEmail.setText(email);
                txtName.setText(first_name + " " + last_name);
                RequestOptions requestOptions = new RequestOptions();
                requestOptions.dontAnimate();

                Glide.with( MainActivity.this).load(image_url).into(circleImageView);

            } catch (JSONException e){
                e.printStackTrace();
            }


        }
    });

    Bundle parameters = new Bundle();
    parameters.putString("fields", "first_name, last_name, email_id");
    request.setParameters(parameters);
    request.executeAsync();
}

private void checkLoginStatus(){

    if (AccessToken.getCurrentAccessToken()!=null)
    {
        loadUserProfile(AccessToken.getCurrentAccessToken());
    }
}

}

这是我在Logcat中显示的错误->>

2020-10-12 12：01：23.621 19597-19602 / com.example.socialmediaintegration I / zygote：将代码缓存容量增加到256KB 2020-10-12 12：01：27.373 19597-19623 / com.example.socialmediaintegration E / GraphResponse：{HttpStatus：400，errorCode：100，subErrorCode：33，errorType：GraphMethodException，errorMessage：不支持的获取请求。 ID为'980066249173751'的对象不存在，由于缺少权限而无法加载，或者不支持此操作。请阅读https://developers.facebook.com/docs/graph-api}上的Graph API文档 2020-10-12 12：01：32.329 19597-19623 / com.example.socialmediaintegration E / GraphResponse：{HttpStatus：400，errorCode：100，subErrorCode：-1，errorType：OAuthException，errorMessage：（＃100）尝试访问不存在节点类型（用户）上的字段（email_id）} 2020-10-12 12：01：32.329 19597-19597 / com.example.socialmediaintegration D / AndroidRuntime：关闭VM 2020-10-12 12：01：32.332 19597-19597 / com.example.socialmediaintegration E / AndroidRuntime：FATAL EXCEPTION：main 流程：com.example.socialmediaintegration，PID：19597 java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'java.lang.String org.json.JSONObject.getString（java.lang.String）' 在com.example.socialmediaintegration.MainActivity $ 3.onCompleted（MainActivity.java:102）在com.facebook.GraphRequest $ 1.onCompleted（GraphRequest.java:317）在com.facebook.GraphRequest $ 5.run（GraphRequest.java:1398）在android.os.Handler.handleCallback（Handler.java:790）在android.os.Handler.dispatchMessage（Handler.java:99）在android.os.Looper.loop（Looper.java:164）在android.app.ActivityThread.main（ActivityThread.java:6626）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:438）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:811）

Answer 1

在此错误行

Attempt to invoke virtual method 'java.lang.String 
org.json.JSONObject.getString(java.lang.String)' on a null object reference

据说您的JSONObject实例为null，并抛出NullPointerException

从JSONObject读取数据之前，您首先需要检查请求是否成功

“检查处理错误”部分

https://developers.facebook.com/docs/android/graph

每当我运行android应用程序时，它就会意外崩溃

1 个答案: