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java - 我无法使用毕加索库显示图片

问题描述

包括来自@Droidman 的 Picasso 库。图书馆真的很不错。但是，如果我宣布有问题，或者我没有在屏幕上正确显示图片。我理解正确，我可以在 .into() 方法中使用带有接收到的 ID 的对象吗？也许我还没有把图书馆连接到最后。

package com.example.my_ugf;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
import com.squareup.picasso.Picasso;

public class MainActivity extends AppCompatActivity {
//final public String URL_poster = "https://udmfil.ru/";
public ImageView imageview_poster;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
    imageview_poster.findViewById(R.id.imageview_poster);
    Picasso.get().load("/upload/iblock/95a/95aa56e9694ebd46e2855e7167966cfd.jpg")
            .resize(50, 50)
            .centerCrop()
            .into(imageview_poster);
}
}

这就是日志产生的。

2021-11-17 09:46:20.345 29475-29475/com.example.my_ugf E/libc: Access denied finding property "ro.vendor.df.effect.conflict"
2021-11-17 09:46:20.363 29475-29552/com.example.my_ugf E/Perf: Fail to get file list com.example.my_ugf
2021-11-17 09:46:20.367 29475-29552/com.example.my_ugf E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2021-11-17 09:46:20.451 29475-29475/com.example.my_ugf D/View: com.example.my_ugf initForcedUseForceDark: 1
2021-11-17 09:46:20.614 29475-29475/com.example.my_ugf D/AndroidRuntime: Shutting down VM
2021-11-17 09:46:20.616 29475-29475/com.example.my_ugf E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.my_ugf, PID: 29475
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.my_ugf/com.example.my_ugf.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.ImageView.findViewById(int)' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(Unknown Source:621)
    at android.app.ActivityThread.handleLaunchActivity(Unknown Source:47)
    at android.app.servertransaction.LaunchActivityItem.execute(Unknown Source:63)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(Unknown Source:77)
    at android.app.servertransaction.TransactionExecutor.execute(Unknown Source:73)
    at android.app.ActivityThread$H.handleMessage(Unknown Source:43)
    at android.os.Handler.dispatchMessage(Unknown Source:19)
    at android.os.Looper.loop(Unknown Source:242)
    at android.app.ActivityThread.main(Unknown Source:98)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(Unknown Source:11)
    at com.android.internal.os.ZygoteInit.main(Unknown Source:275)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.ImageView.findViewById(int)' on a null object reference
    at com.example.my_ugf.MainActivity.onCreate(MainActivity.java:18)
    at android.app.Activity.performCreate(Unknown Source:19)
    at android.app.Activity.performCreate(Unknown Source:1)
    at android.app.Instrumentation.callActivityOnCreate(Unknown Source:3)
    at android.app.ActivityThread.performLaunchActivity(Unknown Source:376)
    at android.app.ActivityThread.handleLaunchActivity(Unknown Source:47) 
    at android.app.servertransaction.LaunchActivityItem.execute(Unknown Source:63) 
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(Unknown Source:77) 
    at android.app.servertransaction.TransactionExecutor.execute(Unknown Source:73) 
    at android.app.ActivityThread$H.handleMessage(Unknown Source:43) 
    at android.os.Handler.dispatchMessage(Unknown Source:19) 
    at android.os.Looper.loop(Unknown Source:242) 
    at android.app.ActivityThread.main(Unknown Source:98) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(Unknown Source:11) 
    at com.android.internal.os.ZygoteInit.main(Unknown Source:275) 
2021-11-17 09:46:20.624 29475-29475/com.example.my_ugf E/MQSEventManagerDelegate: failed to get MQSService.
2021-11-17 09:46:20.625 29475-29475/? D/OOMEventManagerFK: checkEventAndDumpForJE: 0
2021-11-17 09:46:20.625 29475-29475/? E/MQSEventManagerDelegate: failed to get MQSService.
2021-11-17 09:46:20.653 29475-29475/? I/Process: Sending signal. PID: 29475 SIG: 9
2021-11-17 09:46:19.865 29475-29475/? I/.example.my_ug: Late-enabling -Xcheck:jni
2021-11-17 09:46:19.894 29475-29475/? E/.example.my_ug: Unknown bits set in runtime_flags: 0x8000
2021-11-17 09:46:19.865 29475-29475/? I/.example.my_ug: Late-enabling -Xcheck:jni
2021-11-17 09:46:19.894 29475-29475/? E/.example.my_ug: Unknown bits set in runtime_flags: 0x8000
2021-11-17 09:46:19.865 29475-29475/? I/.example.my_ug: Late-enabling -Xcheck:jni
2021-11-17 09:46:19.894 29475-29475/? E/.example.my_ug: Unknown bits set in runtime_flags: 0x8000

标签： javaandroid

解决方案

例外是

Caused by: java.lang.NullPointerException: println needs a message

这是通过Log.i调用发生的 - 您null作为 message 参数传入，这是不允许的。由于您vol在调用该gtUrlImage方法之前进行了空值检查，我猜它发生在这里：

    // arg array is full of nulls
    String[] arg = new String[10];
    ...
    // index is 20 (-1 + 21) if this sequence wasn't found
    index = poster.indexOf("m-img buy") + 21;
    ...
    // array entry is only set if index is not 20, i.e. if that sequence was found
    if (index!=20) arg[i]= poster.substring(index, index + 55);
    // if the sequence wasn't found, arg[i] is still null
    Log.i("UGF",arg[i]);

所以基本上，如果你读到一个不包含的行，"m-img buy"那么该Log行就会崩溃。您必须弄清楚为什么第二次会得到这些行，并弄清楚如何处理它们 - 或者只是避免记录它们（或用于String.valueOf(arg[i])安全地将 null 转换为字符串）

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