jdk/test/com/sun/jdi/GetUninitializedStringValue.java

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/**
 * @test
 * @bug 8021897
 * @summary Test getting the value for an uninitialized String object
 * @author Staffan Larsen
 *
 * @run build TestScaffold VMConnection TargetListener TargetAdapter
 * @run compile -g GetUninitializedStringValue.java
 * @run driver GetUninitializedStringValue
 */
import com.sun.jdi.ReferenceType;
import com.sun.jdi.StackFrame;
import com.sun.jdi.StringReference;
import com.sun.jdi.ThreadReference;
import com.sun.jdi.event.BreakpointEvent;

 /********** target program **********/

class GetUninitializedStringValueTarg {
    public static void main(String[] args) {
        new String("foo");
        System.out.println("Goodbye from GetUninitializedStringValueTarg!");
    }
}

 /********** test program **********/

public class GetUninitializedStringValue extends TestScaffold {
    ReferenceType targetClass;
    ThreadReference mainThread;

    GetUninitializedStringValue (String args[]) {
        super(args);
    }

    public static void main(String[] args)
        throws Exception
    {
        new GetUninitializedStringValue (args).startTests();
    }

    /********** test core **********/

    protected void runTests()
        throws Exception
    {
        /*
         * Run to String.<init>
         */
        startUp("GetUninitializedStringValueTarg");
        BreakpointEvent bpe = resumeTo("java.lang.String", "<init>", "(Ljava/lang/String;)V");

        /*
         * We've arrived. Look at 'this' - it will be uninitialized (the value field will not be set yet).
         */
        StackFrame frame = bpe.thread().frame(0);
        StringReference sr = (StringReference)frame.thisObject();
        if (!sr.value().equals("")) {
            throw new Exception("Unexpected value for the uninitialized String");
        }

        /*
         * resume the target listening for events
         */
        listenUntilVMDisconnect();
    }
}