为Android项目创建自己的jar库时出错

Question

目前我正在研究如何在Android Studio中创建jar库的基础知识.

我按照如何从Android Studio项目中创建一个.jar以及如何从android studio教程创建一个jar文件.并完成了第一个教程中描述的每个步骤.

但是,当我构建并运行此库项目时,它向我显示以下错误

错误:任务':app:preDexDebug'的执行失败.com.android.ide.common.process.ProcessException:org.gradle.process.internal.ExecException:进程'命令'C:\ Program Files\Java\jdk1.8.0_60\bin\java.exe''以非完成零退出值1

我在SO中调查了这个问题,但这些问题根本没有帮助我.这对我来说不是内存问题,因为所有其他应用程序都运行得很好.虽然我的项目没有完美编译,但我从我的库文件夹中获取了库jar文件,当我在其他项目中导入该jar作为库时,我得到了相同的错误消息.

所以我想我在这里错过了一些关键点.如果有人遇到类似的问题或者可以帮助我,请给我一些建议.

如果您希望我发布任何代码,请告诉我,我会这样做,谢谢.

我只是添加一个java库模块并在Multiplication那里添加一个非常简单的类(检查下面的代码).然后在我的项目中将该库模块添加为库. 图书馆代码

public class Multiplication {

    public double multiply(int num1, int num2){
        return num1*num2;
    }
}

活动代码

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

    edt1 = (EditText)findViewById(R.id.et1);
    edt2 = (EditText)findViewById(R.id.et2);
    btn  = (Button)findViewById(R.id.btn);
    tv = (TextView)findViewById(R.id.tvRes);

    multiplication = new Multiplication();

    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            double res = multiplication.multiply(Integer.parseInt(edt1.getText().toString()),Integer.parseInt(edt2.getText().toString()));

            tv.setText(Double.toString(res));
        }
    });

的build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 11
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:appcompat-v7:22.2.1'
    compile files('D:/Work_New/MyApplication/libs/mylibjar.jar')
}

完整的错误日志

Information:Gradle tasks [:app:assembleDebug]
:app:preBuild UP-TO-DATE
:app:preDebugBuild UP-TO-DATE
:app:compileDebugNdk UP-TO-DATE
:app:checkDebugManifest
:app:preReleaseBuild UP-TO-DATE
:mylibjar:compileJava UP-TO-DATE
:mylibjar:processResources UP-TO-DATE
:mylibjar:classes UP-TO-DATE
:mylibjar:jar UP-TO-DATE
:app:prepareComAndroidSupportAppcompatV72221Library UP-TO-DATE
:app:prepareComAndroidSupportSupportV42221Library UP-TO-DATE
:app:prepareDebugDependencies
:app:compileDebugAidl UP-TO-DATE
:app:compileDebugRenderscript UP-TO-DATE
:app:generateDebugBuildConfig UP-TO-DATE
:app:generateDebugAssets UP-TO-DATE
:app:mergeDebugAssets UP-TO-DATE
:app:generateDebugResValues UP-TO-DATE
:app:generateDebugResources UP-TO-DATE
:app:mergeDebugResources UP-TO-DATE
:app:processDebugManifest UP-TO-DATE
:app:processDebugResources UP-TO-DATE
:app:generateDebugSources UP-TO-DATE
:app:compileDebugJava UP-TO-DATE
:app:preDexDebug
UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dx.cf.iface.ParseException: bad class file magic (cafebabe) or version (0034.0000)
    at com.android.dx.cf.direct.DirectClassFile.parse0(DirectClassFile.java:472)
    at com.android.dx.cf.direct.DirectClassFile.parse(DirectClassFile.java:406)
    at com.android.dx.cf.direct.DirectClassFile.parseToInterfacesIfNecessary(DirectClassFile.java:388)
    at com.android.dx.cf.direct.DirectClassFile.getMagic(DirectClassFile.java:251)
    at com.android.dx.command.dexer.Main.processClass(Main.java:704)
    at com.android.dx.command.dexer.Main.processFileBytes(Main.java:673)
    at com.android.dx.command.dexer.Main.access$300(Main.java:83)
    at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:602)
    at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:284)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:166)
    at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:144)
    at com.android.dx.command.dexer.Main.processOne(Main.java:632)
    at com.android.dx.command.dexer.Main.processAllFiles(Main.java:510)
    at com.android.dx.command.dexer.Main.runMonoDex(Main.java:280)
    at com.android.dx.command.dexer.Main.run(Main.java:246)
    at com.android.dx.command.dexer.Main.main(Main.java:215)
    at com.android.dx.command.Main.main(Main.java:106)
...while parsing com/MultiplicationTest/Multiplication.class
1 error; aborting
Error:Execution failed for task ':app:preDexDebug'.
> com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.8.0_60\bin\java.exe'' finished with non-zero exit value 1

虽然我在编译项目时没有显示任何错误,但它向​​我显示了我提到的上述错误.

Answer 1

更新2

根据日志,您使用Java 1.8构建*.jar.Android支持的最大java版本是1.7.因此,您必须将源代码兼容性设置为1.7并重建jar文件.

如果您不是从gradle(或Android Studio)构建此jar,则需要更改JDK版本(文件 - >项目结构 - > SDK位置 - > JDK位置).

对于gradle模块,请参阅"Update 1"

更新1

对于你的java模块(你试图从中获取jar)把这些行:

apply plugin: 'java'
sourceCompatibility = 1.7
targetCompatibility = 1.7

尝试将下一个代码放入Android模块的gradle文件中:

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_7
        targetCompatibility JavaVersion.VERSION_1_7
    }
}