如何摆脱 Android Studio 中的这些错误？

【问题标题】：How do I get rid of these errors in Android Studio?如何摆脱 Android Studio 中的这些错误？
【发布时间】：2016-08-07 21:31:48
【问题描述】：

我是一名新手 android 应用程序员，刚开始编写游戏代码。我最近发现了一个视频，其中应该出现一个红色方块并且可以被拖动。我确定并准确地复制了代码。以下是所有代码：

主要活动：

package com.onemorelaugh.mads;

import android.app.Activity;

import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //makes full screen
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
        //gets rid of title bar
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(new GamePanel(this));
    }
}

游戏面板：

package com.onemorelaugh.mads;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Point;
import android.graphics.Rect;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

/**
 * Created by OneMoreLaugh on 8/7/2016.
 */
public class GamePanel extends SurfaceView implements SurfaceHolder.Callback{
    private MainThread thread;
    private RectPlayer player;
    private Point playerPoint;

    public GamePanel(Context context){
        super(context);
        getHolder().addCallback(this);
        thread = new MainThread(getHolder(),this);
        player = new RectPlayer(new Rect(100, 100, 100, 100), Color.rgb(255, 0, 0));
        playerPoint = new Point(150,150);
        setFocusable(true);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height){

    }

    @Override
    public void surfaceCreated(SurfaceHolder holder){
        thread = new MainThread(getHolder(),this);

        thread.setRunning(true);
        thread.start();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        boolean retry = true;
        while (true) {
            try {
                thread.setRunning(false);
                thread.join();
            } catch (Exception e) {e.printStackTrace();}
            retry = false;
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event){
        //return super.onTouchEvent(event);
        switch(event.getAction()){
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_MOVE:
                playerPoint.set((int)event.getX(), (int)event.getY());
        }
        return true;
    }

    public void update() {
        player.update(playerPoint);
    }

    @Override
    public void draw(Canvas canvas){
        super.draw(canvas);
        canvas.drawColor(Color.WHITE);
        player.draw(canvas);
    }
}

游戏对象：

package com.onemorelaugh.mads;

import android.graphics.Canvas;

/**
 * Created by OneMoreLaugh on 8/7/2016.
 */
public interface GameObject {
    public void draw(Canvas canvas);
    public void update();
}

矩形播放器：

package com.onemorelaugh.mads;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.Rect;
/**
 * Created by OneMoreLaugh on 8/7/2016.
 */
public class RectPlayer implements GameObject {

    private Rect rectangle;
    private int color;

    public RectPlayer(Rect rectangle, int color){
        this.rectangle = rectangle;
        this.color = color;
    }
    @Override
    public void draw(Canvas canvas){
        Paint paint = new Paint();
        paint.setColor(color);
        canvas.drawRect(rectangle, paint);


    }

    @Override
    public void update(){

    }

    public void update(Point point){
        rectangle.set(point.x - rectangle.width()/2, point.y - rectangle.height()/2, point.x + rectangle.width()/2, point.y + rectangle.height()/2);
    }
}

主线程：

package com.onemorelaugh.mads;

import android.graphics.Canvas;
import android.view.SurfaceHolder;

/**
 * Created by OneMoreLaugh on 8/7/2016.
 */

public class MainThread extends Thread{
    public static final int MAX_FPS = 30;
    private double averageFPS;
    private SurfaceHolder surfaceHolder;
    private GamePanel gamePanel;
    private boolean running;
    public static Canvas canvas;

    public void setRunning(boolean running){
        this.running = running;
    }

    public MainThread(SurfaceHolder surfaceHolder, GamePanel gamePanel){
        super();
        this.surfaceHolder = surfaceHolder;
        this.gamePanel = gamePanel;

    }

    @Override
    public void run(){
        long startTime;
        long timeMillis = 1000/MAX_FPS;
        long waitTime;
        int frameCount = 0;
        long totalTime = 0;
        long targetTime = 1000/MAX_FPS;

        while(running){
            startTime = System.nanoTime();
            canvas = null;
            try {
                canvas = this.surfaceHolder.lockCanvas();
                synchronized (surfaceHolder) {
                    this.gamePanel.update();
                    this.gamePanel.draw(canvas);
                }
            }catch(Exception e){e.printStackTrace();}
            finally {
                if(canvas != null){
                    try {
                        surfaceHolder.unlockCanvasAndPost(canvas);
                    }catch(Exception e) {e.printStackTrace();}
                }
            }
            timeMillis = (System.nanoTime() - startTime)/1000000;
            waitTime =  targetTime - timeMillis;
            try {
                if (waitTime > 0)
                    this.sleep(waitTime);
            }catch(Exception e){e.printStackTrace();}
            totalTime += System.nanoTime() - startTime;
            frameCount++;
            if (frameCount == MAX_FPS){
                averageFPS = 1000/((totalTime/frameCount)/1000000);
                frameCount = 0;
                totalTime = 0;
                System.out.println(averageFPS);
            }
        }

    }
}

现在我仔细检查了这段代码，它对视频中的人有效。当我尝试运行它时，（我正在使用 android studio）模拟器会弹出并显示手机的主屏幕，然后显示手机的主屏幕。这就像应用程序崩溃了。以下是错误代码我得到：

Information:Gradle tasks [:app:clean, :app:generateDebugSources, :app:prepareDebugUnitTestDependencies, :app:mockableAndroidJar, :app:generateDebugAndroidTestSources, :app:assembleDebug]
:app:clean
:app:preBuild UP-TO-DATE
:app:preDebugBuild UP-TO-DATE
:app:checkDebugManifest
:app:preReleaseBuild UP-TO-DATE
:app:prepareComAndroidSupportAnimatedVectorDrawable2340Library
:app:prepareComAndroidSupportAppcompatV72340Library
:app:prepareComAndroidSupportSupportV42340Library
:app:prepareComAndroidSupportSupportVectorDrawable2340Library
:app:prepareDebugDependencies
:app:compileDebugAidl
:app:compileDebugRenderscript
:app:generateDebugBuildConfig
:app:mergeDebugShaders
:app:compileDebugShaders
:app:generateDebugAssets
:app:mergeDebugAssets
:app:generateDebugResValues UP-TO-DATE
:app:generateDebugResources
:app:mergeDebugResources
:app:processDebugManifest
:app:processDebugResources
:app:generateDebugSources
:app:preDebugUnitTestBuild UP-TO-DATE
:app:prepareDebugUnitTestDependencies
:app:mockableAndroidJar UP-TO-DATE
:app:preDebugAndroidTestBuild UP-TO-DATE
:app:prepareDebugAndroidTestDependencies
:app:compileDebugAndroidTestAidl
:app:processDebugAndroidTestManifest
:app:compileDebugAndroidTestRenderscript
:app:generateDebugAndroidTestBuildConfig
:app:mergeDebugAndroidTestShaders
:app:compileDebugAndroidTestShaders
:app:generateDebugAndroidTestAssets
:app:mergeDebugAndroidTestAssets
:app:generateDebugAndroidTestResValues UP-TO-DATE
:app:generateDebugAndroidTestResources
:app:mergeDebugAndroidTestResources
:app:processDebugAndroidTestResources
:app:generateDebugAndroidTestSources
:app:incrementalDebugJavaCompilationSafeguard
:app:compileDebugJavaWithJavac
:app:compileDebugJavaWithJavac - is not incremental (e.g. outputs have changed, no previous execution, etc.).
:app:compileDebugNdk UP-TO-DATE
:app:compileDebugSources
:app:buildInfoDebugLoader
:app:transformClassesWithExtractJarsForDebug
:app:transformClassesWithInstantRunVerifierForDebug
:app:transformClassesWithJavaResourcesVerifierForDebug UP-TO-DATE
:app:mergeDebugJniLibFolders
:app:transformNative_libsWithMergeJniLibsForDebug
:app:processDebugJavaRes UP-TO-DATE
:app:transformResourcesWithMergeJavaResForDebug
:app:transformResourcesAndNative_libsWithJavaResourcesVerifierForDebug UP-TO-DATE
:app:transformClassesWithInstantRunForDebug
:app:transformClasses_enhancedWithInstant+reloadDexForDebug UP-TO-DATE
:app:incrementalDebugTasks
:app:prePackageMarkerForDebug
:app:fastDeployDebugExtractor
:app:generateDebugInstantRunAppInfo
:app:coldswapKickerDebug
:app:transformClassesWithInstantRunSlicerForDebug
:app:transformClassesWithDexForDebug
To run dex in process, the Gradle daemon needs a larger heap.
It currently has approximately 910 MB.
For faster builds, increase the maximum heap size for the Gradle daemon to more than 2048 MB.
To do this set org.gradle.jvmargs=-Xmx2048M in the project gradle.properties.
For more information see https://docs.gradle.org/current/userguide/build_environment.html
Error:java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0
Error:  at java.lang.ClassLoader.defineClass1(Native Method)
Error:java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0
Error:  at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
Error:  at java.lang.ClassLoader.defineClass1(Native Method)
Error:  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
Error:  at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
Error:  at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
Error:  at java.security.AccessController.doPrivileged(Native Method)
Error:  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
Error:  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
Error:  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
Error:  at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
Error:  at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
Error:Exception in thread "main" 
Error:  at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
Error:java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0
Error:  at java.lang.ClassLoader.defineClass1(Native Method)
Error:  at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
Error:  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
Error:  at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
Error:  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
Error:  at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
Error:  at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
Error:java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0
Error:  at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
Error:  at java.lang.ClassLoader.defineClass1(Native Method)
Error:  at java.security.AccessController.doPrivileged(Native Method)
Error:  at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
:app:transformClassesWithDexForDebug FAILED
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
Error:  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
Error:  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
Error:  at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
Error:  at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
Error:  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
Error:  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
Error:  at java.security.AccessController.doPrivileged(Native Method)
Error:  at java.security.AccessController.doPrivileged(Native Method)
Error:  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
Error:  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
Error:  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
Error:  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
Error:  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
Error:  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
Error:  at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
FAILURE: Build failed with an exception.
Error:  at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
Error:Exception in thread "main" 
* What went wrong:
Error:  at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
Error:Exception in thread "main" 
Error:  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
Error:  at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
Error:  at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
Error:Exception in thread "main" 
Execution failed for task ':app:transformClassesWithDexForDebug'.
> com.android.build.api.transform.TransformException: java.lang.RuntimeException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.7.0_79\bin\java.exe'' finished with non-zero exit value 1
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
Information:BUILD FAILED
Information:Total time: 4.702 secs
Information:59 errors
Information:0 warnings
Information:See complete output in console

我不知道我做错了什么。谢谢你的回答。

【问题讨论】：

  • 似乎是由于堆大小低导致构建失败。查看消息来自要在进程中运行 dex，Gradle 守护进程需要更大的堆。

标签： android


【解决方案1】：

密钥在第一行Error：

Error:java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0

在谷歌上搜索这个字符串，第一个答案是这个帖子：Unsupported major.minor version 52.0 in my app

编程技巧 #1：当您遇到错误时，您要做的第一件事就是查找错误并询问 Google。

【讨论】：

  • 除非该问题从未被接受的帖子回答
  • 嘿，非常感谢！它跑了哈哈。但现在对象没有出现。你有什么想法吗？
  • @cricket_007 这并不意味着里面没有这个问题的答案。只是想教如何轻松解决错误。
  • @MattBOneMoreLaugh 老实说，我不知道。我们需要信息来解决问题。留意你的日志。编辑代码以将数据推送到无法正常运行的部分代码的日志中，或者简单地应用断点并对其进行调试，迭代代码。你的问题没有一个简单的答案。此外，作为一名程序员还意味着在向社区提问之前要进行大量研究。如果你不做任何研究，只问每个问题，会发生两件事：你没有获得足够的经验，而且你永远不会结束你的项目，因为它们将永远持续到结束 xD
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